taxonID	type	description	language	source
03D43D5BFFC6FFAAC099F8B3FC54456B.taxon	description	Figures 2 – 3	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFC6FFAAC099F8B3FC54456B.taxon	description	Description: Shell subcircular with semitransparent conical dorsal valve and flat ventral valve. Ventral valve very thin, attached to a hard substrate and markedly smaller than dorsal valve. Large subperipheral pedicle opening in ventral valve. Holoperipheral growth with apex slightly behind valve centre. Surface marked by dense concentric growth lines. Shell chitinophosphatic, impunctate and in most cases partly transparent. Juvenile shells nearly white or colourless, becoming yellow, reddish brown or even dark brown with increasing size. Dorsal valve margin with numerous radiating mantle setae, very long along anterior margin, shorter posteriorly. Ventral mantle margin lined with dense, short setae. No hinge. Maximum length 8 mm. Depth range: Minimum range is 658 – 5530 m depth for live specimens (Davidson 1880; Zezina 2014). Although Dall (1920) reported two specimens from 294 fathoms (or possibly metres) off the coast of Florida, these should preferably be verified. Zezina (2010) also reported specimens from as shallow as 366 – 525 m depth near the Scandinavian Peninsula, in the South Ocean and the Malay Archipelago; however, more detailed information is missing and verification would thus be preferable. Temperature range: - 1.2 – 3.5 ˚ C (Jackson 1912; this study). Salinity range: 34.9 – 35.1 (4 measurements) (this study). Substrate: Attached to rock, bones or shells, but typically on bottoms dominated by ooze (Davidson 1880; Wesenberg-Lund 1941; Brunton & Curry 1979; this study). Geography: Panoceanic deep-water species mainly found along the mid-ocean ridges as well as along the bases of continental slopes. Presently not recorded from the Greenland Sea and the Norwegian Sea (Figure 3). Since the species is reported from both the North Atlantic and an empty shell from the Canadian Basin in the Arctic Ocean (e. g., Wesenberg-Lund 1941; Brunton & Curry 1979; Zezina 1997 a, 2010), it is likely also living in the deep parts of the Norwegian and the Greenland Sea.	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFC4FFACC099FE30FEB84548.taxon	description	Figures 4 – 6 Patella Kermes da Costa & Humphrey, in da Costa (1770).	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFC4FFACC099FE30FEB84548.taxon	description	Description: Shell transverse oval or subangular with low conical dorsal valve and nearly straight and narrow posterior margin. Holoperipheral growth with apex slightly behind mid-valve length. Ventral valve cemented to hard substrate. Shell smooth, with fine radiating striation or reflecting surface of substrate. Shell matrix endopunctate. Dark brown or reddish outer layer, with light grey inner shell layer. No hinge. Dorsal interior with distinct muscle scars. Anterior adductor muscle scars not raised or slightly raised. Tiny dorsal ridge. Ventral interior rarely with calcified posterior adductor muscle scars. Anterior adductor muscles attached to organic rostellum. Outer margin poorly defined and relatively densely tuberculate. Maximum width 25 mm. Depth range: 4 – 1805 m depth, though mostly 10 – 400 m depth (Zezina 2010; Robinson 2017; Toma et al. 2022; this study). Observations from visual surveys of the coastal waters of Norway indicate that dense populations are likely widespread on submarine cliff walls and rocky bottoms in these latitudes in a depth zone from the lower part of a belt of dense serpulid tubeworm populations and downwards (Figure 5). In the Vestfjord area of Nordland, this brachiopod zone seems to be mostly between 100 and 200 m in depth; however, it extends to shallower depths in many places. This compares well with visual surveys in the Mediterranean where dense populations were found especially frequent on cliff walls at 80 – 500 m depth, though with geographic variations (Toma et al. 2002). Temperature range: 1.8 – 11.0 ˚ C (Grieg 1924; this study). However, Brand et al. (2003) gave the temperature range 6 – 21 ˚ C, indicating a much higher upper range than found in the present study. Salinity range: 29 – 37 (Brand et al. 2003). Oxygen range: 55 – 113 % for oxygen saturation of bottom water (this study). Current velocity: Mean current velocity between 1.1 – 9.5 cm / s, with daily maxima generally between 0 – 30 cm / s, with a maximum velocity of 4.4 – 42.5 cm / s over 1 month of measurements (this study). Substrate: Attached to cliff faces, boulders, artificial substrates and the hard skeletons of other organisms (Brunton & Curry 1979; Toma et al. 2022; this study). Mostly collected on sea floors dominated by sand, shell sand, gravel, cobbles and / or rock (Thomsen 2001), though visual surveys indicate this is a bias reflecting the sampling methods (Toma et al. 2022; this study).	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFC4FFACC099FE30FEB84548.taxon	distribution	Geography: Svalbard, Norway (but rare in NE Finnmark), Iceland, the Faroe Islands, Greenland (a live specimen collected on the west coast and one empty shell from the SE coast), SW Sweden, Great Britain, France, Spain, Portugal, the Mediterranean, Azores, Morocco, Cape Verde, Madeira, the Canary Islands, the Mexican Gulf and the Caribbean (Robinson 2017; this study) (Figure 6).	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFC4FFACC099FE30FEB84548.taxon	discussion	Remarks: No live specimens appear to have been collected around Svalbard before 1900; however, this is likely reflecting the sampling methods.	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFC3FFADC33BFAD0FAF54B28.taxon	description	Figures 7, 8	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFC3FFADC33BFAD0FAF54B28.taxon	description	Depth range: 520 – 4390 m depth and mostly from deeper than 1000 m (Posselt 1898; Zezina 2010). Specimens sampled at 35 – 450 m depth in Norway, Iceland, Greenland and the USA have also been referred to as this species (e. g., Dall 1920; Wesenberg-Lund 1938, 1939, 1940 a, 1941). However, since one-third of these were located and examined at the visited museums and all turned out to be juvenile shells of Macandrevia cranium and Hemithiris psittacea, the rest are presently considered doubtful. Temperature range: - 1.2 – 3.4 ˚ C (this study). Salinity range: 32.3 – 35.1 (Wesenberg-Lund 1940 a; Thomsen 2012; this study). Substrate: Attached to sand grains, rocks, foraminiferan sand tubes and other hard surfaces on mud-dominated sea floors (Posselt 1898; Brunton & Curry 1979; this study). Geography: Arctic Ocean off Graham Bell Island in the archipelago of Franz Josef Land, West of Bjørnøya, Norway (Nordland and Troms, and possibly also South to Vestland), Iceland, W Greenland, E Canada, Atlantic Ocean, Ireland, eastern USA, Azores, Morocco, Cuba, the Caribbean, and Panama (Fischer & OEhlert 1891; Posselt 1898; Dall 1920; Wesenberg-Lund 1939, 1940 a; Cooper 1973 a; Zezina 1997 a, 2008, 2014; Thomsen 2012).	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFC3FFADC33BFAD0FAF54B28.taxon	discussion	The species is also reported from the Falkland Islands in the SW Atlantic, off South Africa, and as empty shells from the Tasman Sea at Macquarie Island, S of New Zealand (Cooper 1973 a; Zezina 2008, 2010, 2014). Although the shell morphology is very similar, these specimens require a rigorous examination since they are, as already pointed out by Cooper (1973 a), very far outside the normal known distribution of the species. Based on the available coordinates, this deep-water species appears to prefer the shelf edge, slope and abyssal marine environments.	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFC2FFAFC33BF8F3FE684AA8.taxon	description	Figures 1 A, 1 B, 1 F, 1 J, 9, 10	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFC2FFAFC33BF8F3FE684AA8.taxon	description	Description: Shell with subtriangular or subpentagonal outline and rather acutely pointed beak. Large specimens approximately as wide as long. Anterior commissure uniplicate on specimens larger than 16 mm, while gently unisulcate on specimens smaller than 4 mm. Lateral valve commissure unevenly curved. Ornament developing from 1.2 – 4 mm valve length and outwards as fine, broad and very flat radiating ribs or relatively well-separated striae. Shell matrix impunctate. Colour dark bluish, dark grey or brownish except in small specimens, which are light-coloured and transparent. Ventral umbo beak-shaped and rather long. Rudimentary triangular deltidial plates not joining but forming a roughly U-shaped pedicle opening. Distinct pedicle collar. Elongate, unbranched pedicel. Small specimens with setae protruding as prolongation of striae. Well-developed dental plates. Crura flattened. Weak and short dorsal median ridge. Maximum length 30.4 mm. Depth range: 0 – 2078 m depth, though rarely found deeper than 400 m, and only two reports from deeper than 1000 m depth (Cooper 1973 a; this study). Temperature range: - 2 – 12 ˚ C (Knipowitsch 1901; Ullmann et al. 2017). Salinity range: 26.2 – 35.5 (Zezina 2008; this study). Oxygen range: Oxygen saturation 83 – 105 % (this study). Current velocity: Mean current velocity of 2.6 – 11.7 cm / s, with daily maxima of 4 – 30 cm / s and an absolute maximum velocity of 13.3 – 72.2 cm / s over 1 month of measurement (this study). Substrate: Usually attached to small pebbles, shells or rocks, but can be attached to any kind of hard surface such as serpulid and Nothria tubes, bryozoans, Cirripedia fragments, rhodoliths or even Foraminifera and sand grains (this study). Found on mud- or sand-dominated sea floors mixed with shell sand, or on gravel, pebbles, stones, calcareous red algae, rock grounds or vertical cliffs (Leche 1878; Posselt 1898; Arndt & Grieg 1933; Wesenberg-Lund 1940 a, b; Thomsen 2012; this study).	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFC2FFAFC33BF8F3FE684AA8.taxon	distribution	Geography: Arctic Ocean, E and W Canada, E and W Greenland, Svalbard, Jan Mayen, Kara Sea, Laptev Sea, the White Sea, Norway (from Folda in Nordland and north), S and W of Iceland, W USA, and Japan (e. g., Posselt 1898; Lamy 1913; Grieg 1933; Brunton & Curry 1979; Zezina 1997 b, 2008; this study).	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFC2FFAFC33BF8F3FE684AA8.taxon	discussion	The species is also reported from the North Sea, Faroe Islands, at the Hebrides, Ireland, Orkney Isles and Shetland Isles (e. g., Lyell 1842; Dall 1920; Brunton & Curry 1979; Thomsen 2001). Following Jeffreys (1863, 1878) and based on specimens examined at the Natural History Museum of London, all certain observations around the British Isles are empty and likely of glacial age. The reported presence at the Faroe Islands by Lyell (1842) was based on the apparent glacial material (BMNH PI ZB 1667). Additionally, according to Thomsen (2001), there are no other possible recent specimens known from the area. Jeffreys (1878) mentioned the species from Drontheim (= Trondheim) in Trøndelag, Norway, while Wesenberg-Lund (1939) reported it from Brettingsnes in the Trondheimsfjord. However, the latter are two empty shells most likely of glacial age. The first was a re-occurring mistake that Jeffreys (1869 b: 164) admitted, using Trondheim instead of Tromsø. Dall (1920) listed a specimen from Bergen in Vestland, Norway. According to the collection list, the University Museum of Bergen also houses a specimen from that area. However, the latter was missing, and both are most likely not recent shells. In the collections housed at the Natural History Museum of London was a single specimen collected alive (BMNH PI B 24769) with no other information than ‘ North Sea’. The label dates it to before the year 1900. However, it seems more likely that the information is incorrect rather than the specimen actually is originating from the North Sea. Remarks: The species was first named, described and beautifully illustrated by Chemnitz (1785). However, since he used a trinomial name instead of the Linnean binominal system, Gmelin (1791) is accepted as having named the species. Within Norwegian waters, it seems that this Arctic and subarctic species has been retreating northward within the last century since no live specimens appear to have been collected south of 69.2 ° N in Nordland and Troms after 1923, while it was collected from several localities south to 67.6 ° N before then. Despite its wide depth range, Hemithiris psittacea is primarily associated with coastal environments.	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFC0FFAFC338FEF3FC1A4B88.taxon	description	Figures 11, 12	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFC0FFAFC338FEF3FC1A4B88.taxon	description	Description: Shell low equibiconvex to inflated, but with flattened top in anterior profile. Outline elongate subtriangular. Ventral umbo rather short and incurved beak-shaped. Rectimarginate to faintly unisulcate anterior and straight lateral commissure. Triangular, disjunct deltidial plates more than halfway enclosing small to medium-sized pedicle opening. Short pedicle collar. Ornamentation of very fine, dense and radiating striation as well as concentric growth lines. Shell matrix impunctate. Colour light yellow to brownish. Teeth supported by dental plates. Subhorizontal inner hinge plates in dorsal valve connecting socket ridges with crural bases. Lophophore supported by short, thin crura. Sharp-edged short dorsal median septum. Maximum length 36 mm. Depth range: 439 – 3645 m depth (Cooper 1981 a; Zezina 2010). Davidson (1887) gave the extremely shallow depth of 105 m off Southern Portugal for the syntype specimen sampled during the Talisman Expedition in 1883. However, as concluded by Emig (2016) this location is wrong and should have been the Talisman station off Morocco at 1050 m depth reported by Fischer & OEhlert (1891). Temperature range: 6 – 12 ˚ C (Brand et al. 2003). Salinity range: 35 – 36 (Brand et al. 2003).	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFC0FFAFC338FEF3FC1A4B88.taxon	distribution	Geography: English Channel, off SW Ireland, south to the Azores, the Canary Islands and Sudan (Fischer & OEhlert 1891; Brunton & Curry 1979; Cooper 1981 a; Logan et al. 2007; Zezina 2014).	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFC0FFAFC338FEF3FC1A4B88.taxon	discussion	Remarks: Although the year of description is often given as 1886 since that is written on the first page of the paper, it was published in 1887. No holotype was elected in the original description, but Emig (2016) has subsequently elected the Talisman station off Morocco at 1050 m depth as the type locality. Most type specimens from the Talisman expedition have lost their labelling according to Alvarez (2016), but based on the provided pictures it seems most likely that the bigger of the two specimens labelled ML-ZOO-MAL- 00133 is identical with pl. 25, figure 2 – 2 c of Davidson (1887) from the Talisman expedition. That would then be a candidate for election as a lectotype.	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFDFFFB1C33CFBD3FD7E454B.taxon	description	Figures 13, 14	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFDFFFB1C33CFBD3FD7E454B.taxon	description	Depth range: 73 – 2663 m depth (Jeffreys 1878; Dall 1920). Temperature range: 4.6 – 13.6 ˚ C (Jeffreys 1878; Allmen et al. 2010). Salinity range: 38.1 – 38.5 (Allmen et al. 2010). Current velocity: 25 – 100 cm / s (Emig 1987; Emig & García-Carrascosa 1991). Substrate: Rock, gravel, artificial substrates and shells (Fischer & OEhlert 1891; Logan 1979; Allmen et al. 2010; Toma et al. 2022).	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFDFFFB1C33CFBD3FD7E454B.taxon	distribution	Geography: Southern margin of the Celtic Sea, Bay of Biscay, Portugal, the Mediterranean, off North Africa, Cape Verde (Fischer & OEhlert 1891; Logan 1979; Brunton & Curry 1979; Zezina 2014).	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFDEFFB3C33BFB30FDDC4C88.taxon	description	Figures 15, 16	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFDEFFB3C33BFB30FDDC4C88.taxon	description	Description: Shell moderately to strongly equi- to ventribiconvex. Outline subtriangular in smaller specimens, changing to broadly subpentagonal and somewhat truncated. Posterior margins form an angle of 75 – 80 °. Dorsal valve without median fold or depression. Valves rarely with shallow sulcus. Anterior commissure rectimarginate. Relatively dull and thin-shelled, semitransparent to opaque, and endopunctate. Ornamentation generally lacking except for faint growth lines, but faint, dense, radiating striation can occur. Colour whitish. Beak short and rounded in lateral profile, slightly incurved, and often with short triangular deltidial plates narrowly conjoining in larger specimens. Foramen moderately large. Deltidial plates are bordered by ridges, especially in smaller specimens. Pedicle collar thick. Pedicle typically with short rootlets distally. Brachial loop very small and short, with a nearly straight, thin transverse band. Crural process just anterior to mid-loop and loop reaches to 1 / 4 to 1 / 3 valve length. No median ridge in dorsal valve. Dorsal muscle scars reaching 1 / 4 to 2 / 5 (typically 1 / 3) valve length. Dental plates absent. Shell up to 16.4 mm long, 13.5 mm wide and 9.2 mm deep. Depth range: 35 – 481 m depth (Friele 1877 a; this study). Wesenberg-Lund (1941) reported it occurring down to 1500 m depth; however, this was based on misidentified material. Temperature range: - 1.8 – 1.5 ˚ C (this study). Salinity range: 33.7 – 34.9 (this study). Substrate: Clay or sand with stones, fine mud, or on coarse gravel and small stones (Friele 1877 a; Posselt 1898; Hägg 1905; this study). Specimens were found attached to gravel, bryozoan branches, tubes of serpulid worms and to other specimens of Arctosia (this study).	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFDEFFB3C33BFB30FDDC4C88.taxon	distribution	Geography: Greenland, Jan Mayen and N and NE Iceland (Friele 1877 a; Grieg 1933; Zezina 1997 b). Zezina (1997 b) reported the species from just north of Franz Josef Land, bordering the Barents Sea to the North. Reports from off West Spitsbergen and NE Barents Sea by Grieg (1924), latter referred to by Gulliksen et al. (1999) were, as stated by Grieg (1933), misidentifications of young specimens of Hemithiris psittacea. The same is true for reports from SW of Iceland, which proved to be a new species of Xenobrochus following re-examination.	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFDEFFB3C33BFB30FDDC4C88.taxon	discussion	Comment: In many new publications, the year of publication is given as 1878 or even 1879. However, the publication year is specified as 1877 in the original preprint, which, according to the International Code of Zoological Nomenclature (Chapter 5, Article 21.8), is the date of publication. This species is easily confused with Macandrevia cranium but is externally most easily distinguished by the shape of the pedicle opening and thick pedicle collar. The rather few verified occurrences of this species are from 1973 or earlier. It has thus not been possible to evaluate whether there have been any changes in the abundance and distribution of this species. Since this is a truly Arctic species, its geographical range is likely shrinking due to increasing oceanic temperatures.	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFDCFFB5C099FD33FE6A4928.taxon	description	Figures 17, 18 Liothyris arctica – Wesenberg-Lund (1941) [partim], p. 9 – 10. Waldheimiathyris cranium – Wesenberg-Lund (1941) [partim], p. 10 – 12. Liothyrella arctica – Zezina (1997 b) [partim], p. 72. LSID: zoobank. org: act: 14 CCB 184 - 6 D 1 B- 4 FA 6 - 88 CF-E 13 D 04668 E 72	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFDCFFB5C099FD33FE6A4928.taxon	materials_examined	Type locality: Off W Iceland, The Danish ‘ Ingolf’ expedition 1896 st. 84, 62 ° 58 ’ N, 25 ° 24 ’ W, 1192 m depth.	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFDCFFB5C099FD33FE6A4928.taxon	etymology	Etymology: From the geographical name ‘ Island’ (Iceland), around which the species was found.	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFDCFFB5C099FD33FE6A4928.taxon	diagnosis	Diagnosis: Xenobrochus species with elongate, pointy, egg-shaped outline and evenly rounded to slightly flattened anterior margin; beak erect with visible symphytium; permesothyrid medium large foramen; transverse cardinal process; angular brachial loop reaching about 1 / 3 valve length, with broad transverse band with a weak median fold.	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFDCFFB5C099FD33FE6A4928.taxon	materials_examined	Material: Holotype: Reykjanes Ridge, off SW Iceland, the Danish ‘ Ingolf’ expedition 1896 st. 84, 62 ° 58 ’ N, 25 ° 24 ’ W, 1192 m depth, one specimen (NHMD- 1201208 (holotype). Paratypes: Irminger Sea, off W Iceland, the Danish ‘ Ingolf’ expedition 1896 st. 10, 64 ° 24 ’ N, 28 ° 50 ’ W, 1484 m depth, one specimen NHMD- 1186285; Reykjanes Ridge, Iceland Basin, the Danish ‘ Ingolf’ expedition 1896 st. 78, 60 ° 37 ’ N, 27 ° 52 ’ W, 1505 m depth, three specimens and two empty ventral valves (NHMD- 1186283, NHMD- 1186284); Reykjanes Ridge, off SW Iceland, the Danish ‘ Ingolf’ expedition 1896 st. 84, 62 ° 58 ’ N, 25 ° 24 ’ W, 1192 m depth, two specimens and one empty shell (NHMD- 1201194); Irminger Sea, off W Iceland, the Danish ‘ Ingolf’ expedition 1896 st. 90, 64 ° 45 ’ N, 29 ° 06 ’ W, 1070 m depth, two empty shells (NHMD- 1201179); Denmark Strait, W Iceland, the Danish ‘ Ingolf’ expedition 1896 st. 98, 65 ° 38 ’ N, 26 ° 27 ’ W, 260 m depth, two specimens (NHMD- 1201193).	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFDCFFB5C099FD33FE6A4928.taxon	description	Description: Holotype 8.2 mm long and 5.9 mm wide. L / W ratio of 1.16 – 1.50 and generally increasing with shell size. Shell moderately to rather strongly equi- to ventribiconvex. Outline pointy and egg-shaped with evenly rounded to slightly flattened anterior margin. No median folds or depressions developed on valves. Anterior commissure rectimarginate to slightly sulcate. Lateral commissure slightly S-curved. Fragile, transparent to semitransparent and endopunctate. Typically shiny and smooth except for faint growth lines and occasionally very weak radiating striation, as seen on the holotype (Figure 17 a – b). Colour whitish. Beak pointy and only slightly curved in dorsal direction. Comparatively high deltidial plates conjoined and fused to form a visible symphytium, often depressed along midline. Ridges bordering deltidial plates poorly developed or absent. Pedicle foramen moderately large permesothyrid (= beak ridges bisecting foramen in lower half) and circular to subtriangular. Pedicle short and branched in multiple rootlets. Pedicle collar short. Teeth form moderately high transverse plates. Dental plates absent. Cardinal process in dorsal valve a transverse semi-elliptical ridge on top of the inner socket ridges (Figure 17 k, ae). Outer hinge plate connecting inner socket ridges with crural bases narrow, triangular and poorly developed. Inner hinge plates absent. Brachial loop short and narrow, with subparallel sides and a broad, angular transverse band with anterolateral angles. Transverse band gently convex in anterodorsal direction, though a small indention can occur at the suture line at front edge. Crural processes barely anterior of mid-loop length, blunt and bending towards each other. Brachial loop reaches approximately 30 % of valve length. No true dorsal median ridge, though imprints of the two main trunks of the vascular system may create a thickening on the valve floor extending to 30 % of valve length. Dorsal muscle scars clearly visible and reaching slightly anterior of 1 / 4 valve length. Largest specimen 12.4 mm long and 8.3 mm wide. Depth range: 260 – 1505 m depth. Temperature range: 3.5 – 5.9 ˚ C. Salinity range: 34.9 – 35.4. Substrate: Attached to Porifera spicules or bryozoan branches. Geography: North Atlantic Ocean off E and SE Iceland.	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFDCFFB5C099FD33FE6A4928.taxon	discussion	Remarks: The specimens are assigned to the genus Xenobrochus Cooper, 1981 b based on the presence of the diagnostic characters, such as a visible symphytium, small shell size with basically rectimarginate anterior commissure, transverse cardinal process, and a short loop with subparallel sides and an anteriorly convex transverse band. This makes this species the second of that genus to be recorded from the Atlantic Ocean and outside the W Pacific and Indian Ocean when following the opinion of Bitner & Molodtsova (2020) and including Abyssothyris? parva Cooper, 1977 in the genus (see Bitner 2011; Bitner & Molodtsova 2020). To date, 10 species have been included in the genus. These are Xenobrochus africanus (Cooper, 1973 b), X. agulhasensis (Helmcke, 1938), X. anomalus Cooper, 1981 b, X. australis Cooper, 1981 b, X. indianensis (Cooper, 1973 b), X. naudei Hiller, 1994, X. norfolkensis Bitner, 2011, X. parvus (Cooper, 1977), X. rotundus Bitner, 2008 and X. translucidus (Dall, 1920). Most of these species have a distinctly subtriangular or pentagonal outline with a somewhat truncated front, or a subcircular outline distinguishing them from the present species. This includes the subtriangular to subcircular Xenobrochus parvus, which according to descriptions and illustrations of Cooper (1977) and Bitner & Molodtsova (2020) is more equidimensional, is distinctly ventribiconvex, lacks anterolateral angles on the transverse band of the brachial loop, and seems to have a dull shell surface. Among the remaining four, the shallow-water species X. indianensis (from the Indian Ocean and SW Pacific) appears morphologically very close, except for a distinctly more incurved beak and a narrower cardinal process. The equally close X. agulhasensis from approximately 275 m depth off South Africa differs by a very small brachial loop reaching to about 1 / 4 valve length, and a generally lower L / W ratio of approximately 1.2. X. africanus, from the Indian Ocean and SW Pacific with the holotype taken at 366 m depth, has a much more robust shell, slightly truncated front and a distinctly narrower and broadly V-shaped transverse band in the brachial loop. X. australis, from 790 m depth in the South Indian Ocean, has a larger foramen with a longer pedicle collar, while the anterior end of the brachial loop does not bend in the dorsal direction and the L / W ratio of the shell is approximately 1.5.	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFDAFFB6C099FA93FE534B2B.taxon	description	Figures 19, 20	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFDAFFB6C099FA93FE534B2B.taxon	description	Description: Shell outline subpentagonal to nearly egg-shaped, and fully grown specimens generally with narrowly truncated or even incurved front. Anterior commissure gently to moderately uniplicate or, more rarely, rectimarginate. Ornamentation of 9 – 14 radiating, rather coarse costellate ribs per 5 mm counted 10 mm anterior of ventral umbo (occasionally up to 17 ribs). Ribs lacking on specimens less than 1 mm long, but rapidly become high and subangular, then weaken again with increased shell size. Ribs beaded with coarse tubercles on umbonal part, especially the ventral valve. In young specimens, these tubercles tend to partly overhang deep rib-interspaces along valve crest. Umbonal tip of ventral valve continuously becomes resorbed with growth, making umbo less pointed. Pedicle often strongly branched. Deltidial plates lacking or small and separate. Pedicle opening 11 – 13 % as wide as valve. Shell matrix endopunctate. Colour white or yellowish-grey. Short brachial loop often, but far from always, with crural processes joining. Joined crural processes seem to be more common in larger specimens. Brachial loop not pointy in front. Median ridge absent or very rudimentary and restricted to posterior part of valve floor. Long setae radiating out from where ribs meet anterior valve margin. Soft tissue dense with spicules, especially in lophophores. Largest encountered was 26 mm long. Depth range: 12 – 1492 m depth, though most common at 15 – 600 m depth (Jeffreys 1878; this study). By mistake, the maximum depth was given as 1180 ft (~ 2157 m) by Jeffreys (1878), which was then quoted by others; however, in Jeffreys’ station table, the correct depth (1492 m) is given. However, since Jeffreys (1878) did not distinguish Terebratulina septentrionalis from T. retusa, the maximum depth could be for the other species. The maximum depth given Wesenberg-Lund (1938) distinguishing the two species is 1302 m. Temperature range: 0.0 – 13.0 ˚ C (Curry 1982; Thomsen 2001). Jeffreys (1878) reported the species from several British samples, which, according to Carpenter et al. (1869), were taken at sub-zero temperatures down to - 1.2 ˚ C; however, Jeffreys did not distinguish the colder-water species Terebratulina septentrionalis from T. retusa. Salinity range: 33.1 – 35.3 (Nordgaard 1905; Thomsen 2001; this study). Oxygen range: 77 – 105 % saturation (this study). Current velocity: Mean velocity measured at one locality was 9.5 cm / s, with daily maxima mostly 12 – 25 cm / s and 30 cm / s as the absolute maximum measured over 1 month (this study). Substrate: Attached to bryozoans, hydroids, shells, sand, stones, Porifera, seaweeds, etc. (Jeffreys 1863; Brunton & Curry 1979; Thomsen 2001; this study). Sea floor typically dominated by sand, shell sand, gravel, cobbles or stones (Thomsen 2001).	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFDAFFB6C099FA93FE534B2B.taxon	distribution	Geography: Bjørnøya, Norway, Iceland, the Faroe Islands, SW Sweden, Great Britain, France, Spain, Portugal, the Mediterranean, the Canary Islands and the Cape Verde Islands (Fischer & OEhlert 1892; Brunton & Curry 1979; Cohen et al. 1993; Thomsen 2001; Logan et al. 2007; this study). Neither the northernmost (Bjørnøya), easternmost two (Finnmark), nor all the records from the NW side of Iceland have been verified in the present study or in molecular studies.	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFDAFFB6C099FA93FE534B2B.taxon	discussion	Remarks: A comparison with the next and closely related Terebratulina septentrionalis is provided in the comments on that species. The shells are often overgrown by a Demospongia of the genus Hymedesmia (Tendal & Thomsen 2005). Plotting specimens according to the century of sampling did not reveal any changes in distribution within Norwegian waters. Despite the impression of the map, this species is only sporadically encountered along northern Norway.	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFD9FFB8C099F953FACD4C6B.taxon	description	Figures 21, 22	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFD9FFB8C099F953FACD4C6B.taxon	description	Description: This species is very similar to Terebratulina retusa and has overlapping ranges of almost all diagnostic characters. As noted by Sars (1878) and Wesenberg-Lund (1941), T. septentrionalis tends to have the following characters: more egg-shaped outline; rectimarginate or weakly uniplicate anterior commissure; thinner shell-wall; weaker growth lines; denser ribs with 14 – 22 usually low subtriangular or rounded radiating ribs per 5 mm counted 10 mm anterior of ventral umbo; tubercles on umbonal crest missing or less strongly developed; stronger tubercles usually scattered laterally on umbone; ribs lower and tend to be nearly absent distally on larger specimens; often slightly wider pedicle opening (11 – 15 % as wide as valve). In the present study, the most stable difference from T. retusa was found to be the absence of or denser, lower and more transverse tubercles never overhanging deep interspaces between the ribs on the ventral umbonal crest. The largest measured specimen was 27.5 mm long. Depth range: 0 – 3614 m depth (Dall 1920; Brunton & Curry 1979), but mostly occurring at 10 – 550 m depth, with the seconddeepest recorded occurrence at approximately 1325 m (Thomsen 2012). Temperature range: - 1.7 – 10.6 ˚ C (Allmen et al. 2010; this study). Salinity range: 28 – 35.4 (Brand et al. 2003; this study). Oxygen range: 55 – 104 % saturation (this study). Current velocity: Mean current velocity at four locations measured at 2.7 – 6.9 cm / s, with a normal daily maximum of 2 – 18 cm / s and 10.8 – 24.8 cm / s as the absolute maximum over 1 month of measurement (this study). Substrate: Commonly attached to serpulid tubes, but also to shells, shell sand, branched bryozoans, the coral Desmophyllum, Porifera, other polychaete tubes, or gravel (this study).	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFD9FFB8C099F953FACD4C6B.taxon	distribution	Geography: S, W and E Greenland, Svalbard (Bjørnøya, Spitsbergen, and verified from off northern Nordaustlandet in 2009, and from the Hinlopen Strait), Murmansk, the White Sea, Norway (Hordaland and North), Baffin Bay, East Canada, Jan Mayen, Iceland, Scotland, Ireland and E USA (Grieg 1933; Wesenberg-Lund 1941; Brunton & Curry 1979; Curry & Endo 1991; Thomsen 2001; Allmen et al. 2010; Thomsen 2012; this study).	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFD9FFB8C099F953FACD4C6B.taxon	discussion	Remarks: Terebratulina septentrionalis has been synonymised with the species Terebratulina retusa several times (e. g., Jeffreys 1878; Davidson 1880; Posselt 1898; Knipowitsch 1901; Hägg 1905; Zezina 1997 a, c) since the species are very similar and intermediate morphotypes are found to occur in places where both species are present (e. g., Wesenberg-Lund 1941; Lüter et al. 2017). Cohen et al. (1991) addressed this question through a molecular study on specimens from British and Icelandic waters. They concluded that there were two distinct species and found no evidence of hybridisation. Recently, in their follow-up study, Lüter et al. (2017) found hybrids in places where both species co-occur in Iceland. Hybridisation could explain some observed morphological trends along Norway, where T. retusa tends to show finer costellae, thinner shells and weaker tubercles in northern regions dominated by T. septentrionalis. Sars (1878) found that the crural processes in T. septentrionalis were not connected, in contrast to those of T. retusa. This difference was not supported by the examined material in the present study, which included both specimens with disconnected and connected processes for both species. Logan (1979) found there to be an ontogenetic trend with the connection generally developing latter in T. septentrionalis than in T. retusa. Blochmann (1908) used the spicules in the tissue to distinguish the two species. However, Wesenberg-Lund (1941) questioned the usefulness of this method. In the present study, I also failed to separate the two species based on spicules. The variability and usefulness of all the expected diagnostic features of the two species were rigorously examined based on a large collection containing a wide range of shell sizes, population samples and geographically separated material of both species. As expected, the shell shape and ornamentation of both species show strong variability between specimens within the same population, but also along different growth stages of single specimens, with most features varying independently of each other. It can be concluded that the range of variation within each single feature shows a considerable overlap between the two species. The most stable differences surprisingly turned out to be the ornamentation on the umbonal part, especially in specimens 2 – 10 mm in length. Eucalathis ergastica Fischer & OEhlert, 1890 Figures 23, 24 Eucalathis ergastica Fischer & OEhlert, 1890, p. 73. Description: Shell low to moderately ventribiconvex and slightly longer than wide. Outline subtriangular to subpentagonal and widest close to front. Ventral umbo pointed and with moderately high interarea bisected by elongate subtriangular pedicle opening. Pedicle divided into many rootlets. Anterior commissure rectimarginate. Dorsal valve often with slight sulcus. Ornamentation of 14 – 27 costellate ribs, as well as abundant and strong lamellar growth breaks. Ribs triangular in cross section. Middle dorsal rib not larger than the others. Shell matrix endopunctate with very tiny punctae. Colour porcelain white to slightly yellowish. Broad hinge teeth not supported by dental plates. Short and anteriorly directed loop. Crural processes not meeting. Dorsal median septum lacking. Maximum shell size 7 mm. Depth range: 280 – 2736 m depth (Logan 2007). Temperature range: 9.5 – 12 ˚ C (this study). Substrate: Mud, sand, stones and rock, and often associated with corals (Fischer & OEhlert 1891; Logan 1983; Anadón 1994; Anadón et al. 2022). Can also be attached to Porifera as in the illustrated examples. Due to the past synonymisation and confusion of the two species, the published geographic distribution — especially in the Arctic region — may be based on a mix of the species in many cases. Therefore, in the present study, the more uncertain observations were excluded. Some of the earlier identifications made in the present study are also erroneous since a greater understanding of the value of various diagnostic features evolved along the way. This latter problem has been addressed to some extent by re-examining the specimens from many of the border occurrences. Geography: Celtic Sea, Bay of Biscay, W Spain, Azores, Morocco, the Canary Islands and Western Sahara (Fischer & OEhlert 1890; Cooper 1981 a; Logan et al. 2007). Material collected from southern Norway during the present century was not available for the present study. Therefore, no conclusions can be drawn from the absence of data from this area. Like the previous species, this species is often overgrown by sponges, most likely of the genus Hymedesmia (belonging to Demospongia) (Tendal & Thomsen 2005; Thomsen 2012).	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFD9FFB8C099F953FACD4C6B.taxon	description	Figures 23, 24	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFD9FFB8C099F953FACD4C6B.taxon	description	Description: Shell low to moderately ventribiconvex and slightly longer than wide. Outline subtriangular to subpentagonal and widest close to front. Ventral umbo pointed and with moderately high interarea bisected by elongate subtriangular pedicle opening. Pedicle divided into many rootlets. Anterior commissure rectimarginate. Dorsal valve often with slight sulcus. Ornamentation of 14 – 27 costellate ribs, as well as abundant and strong lamellar growth breaks. Ribs triangular in cross section. Middle dorsal rib not larger than the others. Shell matrix endopunctate with very tiny punctae. Colour porcelain white to slightly yellowish. Broad hinge teeth not supported by dental plates. Short and anteriorly directed loop. Crural processes not meeting. Dorsal median septum lacking. Maximum shell size 7 mm. Depth range: 280 – 2736 m depth (Logan 2007). Temperature range: 9.5 – 12 ˚ C (this study). Substrate: Mud, sand, stones and rock, and often associated with corals (Fischer & OEhlert 1891; Logan 1983; Anadón 1994; Anadón et al. 2022). Can also be attached to Porifera as in the illustrated examples.	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFD9FFB8C099F953FACD4C6B.taxon	distribution	Geography: Celtic Sea, Bay of Biscay, W Spain, Azores, Morocco, the Canary Islands and Western Sahara (Fischer & OEhlert 1890; Cooper 1981 a; Logan et al. 2007).	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFD6FFB9C096FC73FAB14FCB.taxon	description	Figures 25, 26	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFD6FFB9C096FC73FAB14FCB.taxon	description	Description: Shell moderately ventribiconvex. Outline subtriangular to subpentagonal with rounded front and greatest width anteriorly. Shell usually not much longer than wide. Hinge line nearly straight. Ventral umbo pointed and with high interarea bisected by long V- or U-shaped pedicle opening. Deltidial plates small and triangular. Pedicle collar distinct and strongly raised. Pedicle divided into rootlets. Anterior commissure rectimarginate. Ornamentation of 14 – 44 costellate ribs, typically strongly beaded by tubercles — especially on ventral valve. Middle dorsal rib stronger or higher than the others and corresponded by an intercosta or two smaller and lower median costellae on ventral valve. Shell matrix endopunctate with very small punctae. Colour greyish to yellowish white. Crenulate valve margin. Strong and very wide hinge teeth not supported by dental plates. Dorsal valve with short but highly raised crura with a short, fragile loop extension usually not preserved. Median septum lacking, but weak median thickening of valve floor often presents in both valves. Shell up to 5 mm long. Depth range: 549 – 2995 m depth (Brunton & Curry 1979; Logan 2007).	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFD6FFB9C096FC73FAB14FCB.taxon	distribution	Geography: Celtic Sea, Bay of Biscay, Mauritania,? Mediterranean, the Azores, the Mediterranean and south to the Canary Islands (Brunton & Curry 1979; Logan et al. 2007; Zezina 2014).	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFD6FFBBC33BFCB0FEBA4FA8.taxon	description	Figures 27, 28	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFD6FFBBC33BFCB0FEBA4FA8.taxon	description	Description: Minute, thin-walled shell, moderately to inflated biconvex with ventral valve usually slightly shorter but higher than dorsal. Outline egg-shaped oval to subtriangular. Rectimarginate anterior commissure. Hinge line narrow but straight. Ornamentation lacking except for growth lines. Shell matrix semitransparent and densely endopunctate. Colour white or yellowish. Pedicle opening relatively large and V- or U-shaped, extending into the dorsal valve. Ventral umbo short and, in some cases, shorter than dorsal umbo. Deltidial plates rudimentary and not joined. Hinge teeth not supported by dental plates. No visible muscle scars. Dorsal valve with prominent inner and outer socket ridges, the inner of which continues as submarginal ridges on valve floor. Notothyrium (raised platform) bisected by a simple, weak, ridge-like cardinal process. Dorsal median ridge usually present, though rudimentary and restricted to the posterior-most part of the valve floor. Short, broad, but incomplete brachial loop supported by submarginal ridges on valve floor. Lophophores reaching approximately 4 / 5 valve length. Maximum shell length 1.5 mm. Depth range: Intertidal to 46 m depth (Jeffreys 1859; Logan et al. 1997), but empty shells have been collected down to 100 m depth (Harper et al. 1996). Temperature: 11 – 13 ˚ C (Simon & Willems 1999). Substrate: Found attached to rocks, gravel, in shells and serpulid tubes, and on shell sand and sand (Jeffreys 1859; Davidson 1887; Harper et al. 1996; Logan et al. 1997; Francis et al. 2011).	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFD6FFBBC33BFCB0FEBA4FA8.taxon	distribution	Geography: Coastal waters of Scotland, Wales, England, Ireland, the southernmost North Sea off the Netherlands and Belgium, the coast of France in the English Channel, off SE France, the Spanish Bay of Biscay, Portugal, the Adriatic Sea at Croatia, Greece, and on a seamount in the North Atlantic at approximately 30 ° N and 13 ° W (Davidson 1887; Brunton & Curry 1979; Besteiro & Urgorri 1986; Logan et al. 1997; Simon & Willems 1999; Antoniadou & Chintiroglou 2005; Logan et al. 2007; Francis et al. 2011). A Holocene subfossil of the species has also been reported and illustrated from an isostatic raised shell banks located approximately 50 m above present-day sea level near Korshavn on the island Kirkøya at the Oslofjord, Norway (Sars 1865).	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFD6FFBBC33BFCB0FEBA4FA8.taxon	discussion	Remarks: Due to its minute size, Gwynia capsula is extremely easy to miss — even when knowing that it is present. This small size also easily leads to confusion with juvenile specimens of other brachiopod species. Combining this with how many findings have been made around the entire British Isles, it seems very likely that the species is still living along some parts of southern Norway despite no records other than the one subfossil specimen from deposits containing a shelly faunal assemblage pointing towards the Holocene climatic optimum.	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFD4FFBCC098FC13FBCE4A88.taxon	description	Figures 1 I, 29 – 31	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFD4FFBCC098FC13FBCE4A88.taxon	description	Description: Highly variable. Shell equi-biconvex to ventribiconvex. Outline egg-shaped oval to pentagonal with truncated anterior valve margin in large specimens, and typically with dorsal valve about as wide as long. Ventral umbo blunt and short. Hinge line narrow and curved. Anterior commissure generally rectimarginate but can be slightly unisulcate. Small specimens with numerous long and very thin setae along anterior margin, easily falling off during handling. Rudimentary rectangular deltidial plates not joining. Deltidial plates separated from rest of valve by distinct ridges, especially in juveniles. Pedicle short and with a simple attachment base or very rudimentary rootlets. Ornamentation lacking in grown specimens except for very weak and sporadic growth lines. Small specimens often show very fine radiating ridges from which the setae protrude. Shell matrix endopunctate. Colour usually pale brownish, but especially old or empty shells can become grey or whitish. Dental plates supporting hinge teeth in ventral valve. Hinge teeth usually rather small and approximately twice as long as high. Cardinal process in the middle of dorsal hinge area often not developed, but otherwise typically rather broad, triangular and widest posteriorly. Socket ridges (ridges defining sockets for ventral teeth) well developed. Long brachial loop reaching to 2 / 3 to 4 / 5 valve length, with triangular crural processes situated close to base, and with small and few anteriorly directed spines in front. Specimens up to 2 mm long lack median ridge or septum. Specimens between 2 and 5 – 6 mm long develop a high, pillar-like septum highly elevating lophophores. Septum visible on the shell surface as a lighter spot or node around mid-valve length, sometimes extending partway back to umbo. Dorsal septum lost in specimens exceeding 6 mm in length. A study of septal development in this species was conducted by Friele (1877 b). Maximum shell length 31 mm. Depth range: 2 – 4700 m depth (Dall 1920; Anadón et al. 2022), but with the overwhelming majority occurring at 40 – 400 m and only one observation from deeper than 3000 m. Temperature range: - 1.1 – 12.0 ˚ C (Jeffreys 1878; this study). Salinity range: 31.9 – 36.0 (this study). Oxygen range: 55 – 113 % saturation (this study). Current velocity: Mean current velocity was 1.1 – 12.0 cm / s, with daily maxima of approximately 0.2 – 31 cm / s and a maximum velocity of 16.2 – 42.7 cm / s measured over 1 month (this study). Substrate: Attached to sand grains, gravel, stones, exposed bedrock, calcareous algae, corals, bryozoans, cirripeds, serpulid tubes, shells, etc. (Thomsen 1990, 2001; this study) (Figure 30). Mostly on sea floor dominated by sand, shell sand, gravel, cobbles or stones (Thomsen 2001), but can occur on silt- / clay-dominated bottoms.	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFD4FFBCC098FC13FBCE4A88.taxon	distribution	Geography: Greenland, NE America to Rhode Island in the USA, Svalbard, Barents Sea, Novaya Zemlya, Norway, NW Russia, SW Sweden, Iceland, the Faroe Islands, N and W portions of the British Isles, France, Spain, Portugal, W Sahara and the Canary Islands (Jeffreys 1878; Posselt 1898; Derjugin 1915; Grieg 1933; Brunton & Curry 1979; Thomsen 1990, 2001; Gulliksen et al. 1999; Zezina 2014).	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFD4FFBCC098FC13FBCE4A88.taxon	discussion	Remarks: See under Dallina septigera for distinguishing characters from that species. This is undoubtedly by far the most common species in Norwegian waters. Despite a wide depth range, this species prefers coastal and inner shelf environments. Relatively few specimens are found as far north as Svalbard. However, there is no strong evidence of a continuation of the northern expansion of its geographical range that Thomsen (1990) found in association with the strengthening of the warm Atlantic current up along the Norwegian coast during the Holocene warming after the last ice age. Macandrevia cranium has previously been recorded along the mid and northeastern coast of Greenland (Posselt 1898; Arndt & Grieg 1933; Wesenberg-Lund 1940 b; Thomsen 2012). However, four of the seven samples with specimens were located and examined during the present study and solely contained Arctosia arctica. Therefore, it appears likely that the remaining specimens from the area, influenced by the polar water masses of the East Greenlandic Current, also are Arctosia arctica. The presence of Macandrevia cranium along W Greenland is related to the slightly warmed West Greenlandic Current flowing north along the coast.	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFD2FFBEC099FF73FC744C6B.taxon	description	Figures 32, 33	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFD2FFBEC099FF73FC744C6B.taxon	description	Description: Compressed equi- to ventribiconvex shell with L / W ratio 1.06 – 1.43. Outline typically slightly truncated, elongate and egg-shaped, but smaller specimens and occasionally larger specimens are broad and egg-shaped. Dorsal valve usually longer than wide. Shell fragile and rather dull. Ventral umbo small, less prominent and more delicate than that of Macandrevia cranium. Anterior commissure rectimarginate. Deltidial plates rudimentary, bordering moderately sized and elongate pedicle opening. Ridges bordering deltidial plates hardly developed. Ornamentation lacking except for weak growth lines, which are more distinct than those of M. cranium. Shell matrix densely endopunctate. Colour light yellowish-brown. Hinge teeth in ventral valve high, but delicate and supported by short dental plates. Brachial loop in dorsal valve narrow and horseshoe-shaped. Cardinal process is a short ridge between socket ridges and attached directly to valve floor. Small specimens with a short but high septum centred at approximately 2 / 5 valve length. Largest specimen 13 mm long and 10 mm wide. Depth range: 207 – 2652 m (Jeffreys 1876 a, b; Cooper 1973 a). Temperature range: Based on four stations, the range is 1.6 – 4.5 ˚ C (this study). Salinity range: Based on three stations, the range is 34.96 – 35.33 (this study). Substrate: Globigerina ooze with stones (Jeffreys 1876 a). Specimens are found attached to gravel. Geography: NW North Atlantic, Labrador in Canada, and S Greenland (Jeffreys 1876 a; Cooper 1973 a). A ‘ recently dead’ specimen collected NW of Ireland was also assigned to this species by Brand et al. (2003).	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFD1FFBFC33BFDF3FA9E4ECB.taxon	description	Figures 1 D, 1 H, 34, 35	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFD1FFBFC33BFDF3FA9E4ECB.taxon	description	Description: Shell egg-shaped. Rectimarginate anterior commissure. No ornamentation except irregular growth lines. Shell matrix endopunctate. Colour yellowish white. Umbo long, curved and beak-shaped, except in specimens below 3.5 mm long. Pedicle opening very elongate. Deltidial plates usually not joined and rudimentary in small specimens. Pedicle commonly strongly branched. Ventral teeth supported by dental plates. Long pedicle collar (thickening of valve floor) extending to front of dental plates. Dorsal median septum in subadult and adult shells triangular and reaching from umbo to approximately 3 / 5 to 2 / 3 valve length and terminating gradually. Juveniles below 3 mm long with a short, more pedestal-like septum. Brachial loop long. Maximum shell length 13.3 mm. Depth range: 26 – 547 m depth (Friele & Grieg 1901; this study), mostly from the shelf seas at 40 – 400 m depth. This species was described by Wesenberg (1940 a, 1941) from several samples collected deeper than 1000 m. However, a re-examination of the specimens revealed them to be Cryptopora gnomon or juvenile Macandrevia cranium. Temperature range: - 2 – 3.8 ˚ C (Knipowitsch 1901; Grieg 1933; Ullmann et al. 2017). Salinity range: 32.5 – 35.1 (Wesenberg-Lund 1940 a; this study). Substrate: Attached to sand grains, gravel, Sessilia shells, polychaete tubes or bryozoan branches (this study). Found on muddy or sandy bottoms with annelid tubes or gravel (Posselt 1898; Knipowitsch 1901, 1902; Grieg 1933).	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFD1FFBFC33BFDF3FA9E4ECB.taxon	distribution	Geography: Arctic Ocean, N Canada, Greenland, Beaufort Sea, Chukchi Sea, Laptev Sea, Kara Sea, Svalbard, Barents Sea, Norway (Finnmark), N and E Iceland, and Japan (e. g., Jeffreys 1878; Posselt 1898; Derjugin 1915; Grieg 1933; Zezina 1997 a, b; Thomsen 2001; Ullmann et al. 2017).	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFD1FFBFC33BFDF3FA9E4ECB.taxon	discussion	The species is also found in glacial deposits from SW Sweden, the Shetland Islands and the Oslofjord (Lyell 1835 (as Terebratula); Jeffreys 1869 b; Davidson 1887). Three specimens collected by Jeffreys and reported by Davidson (1887) from three stations on the slope at the Western Approaches and from just SW of Portugal have been assigned to this species. The bottom-water temperatures at these stations were 9, 10 and 11.5 ˚ C, respectively (Jeffreys 1878), and thus far higher than where the species otherwise occurs. However, Jeffreys (1878) noted that he did not find any individuals of that species, but had initially misidentified a juvenile Dallina from one of the two northern stations. In fact, the specimen (BMNH PI ZB 790) was a Fallax dalliniformis, which, as a juvenile, is easily confused with Glaciarcula spitzbergensis. The other northern specimen (BMNH PI ZB 4946) was an empty valve of a new species, Dallina lusitanica. Moreover, Brunton & Curry (1979) misread Davidson (1887) and assumed that these two stations were at the Scilla Isles. Glaciarcula spitzbergensis was reported from two places at Trondheim by Wesenberg-Lund (1939); however, both of these finds turned out to be juvenile Macandrevia cranium. The same occurred for the specimens from the Faroe Islands and most of those from Iceland reported by Wesenberg-Lund (1938, 1940 a, c, 1941). Three specimens, which, according to their label are from the Haltenbank off western Norway, are housed at the University Museum of Bergen. However, since there are some information disagreements between labels and information published by Grieg (1933) (he had assigned finds from that locality to the species Hemithiris psittacea), it is likely that the label does not belong to the specimens. Remarks: When comparing new and old observations of this Arctic species, it cannot be excluded that the southern limit of the species is shifting further north, away from Norway.	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFD0FF80C33BFB53FC4D4A08.taxon	description	Figures 36, 37	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFD0FF80C33BFB53FC4D4A08.taxon	description	Description: Shell highly ventribiconvex. Outline subtriangular to semicircular. Ventral umbo high or long. Straight hinge line. Anterior commissure rectimarginate. Ventral umbo high or long and with high apsacline to almost catacline interarea (plane area between hinge line and umbo) bisected by long V- or U-shaped pedicle opening also extending slightly into dorsal valve. Deltidial plates narrow and triangular. Pedicle collar strongly raised but relatively short. Ornamentation of 7 – 18 broad, radiating ribs, and shell surface marked by growth lines. Ribs fading away distally on largest specimens. Shell matrix endopunctate. Colour light honey or greyish. Dental plates lacking. Ventral valve floor with narrow and low median septum or ridge. Long brachial loop reaching 2 / 3 valve length and attached to median and two or (rarely) four lateral ridges or septa. Dorsal median septum or ridge reaching close to valve front. Maximum shell size 6.7 mm long. Depth range: Minimum range is 5 – 1940 m depth (Gaspard 2003; Logan 2007). The species is rarely found deeper than 500 m. Temperature range: 11.5 – 25 ˚ C (Jeffreys 1878; Brand et al. 2003). Salinity range: 37 – 38 (Brand et al. 2003).	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFD0FF80C33BFB53FC4D4A08.taxon	distribution	Geography: English Channel, Southernmost Celtic Sea, Bay of Biscay, Portugal, the Mediterranean, Madeira, the Canary Islands and the Cape Verde Islands (Jeffreys 1878; Logan 1979; Logan et al. 2007; Evangelisti et al. 2011).	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFD0FF80C33BFB53FC4D4A08.taxon	discussion	Remarks: Bruguière (1789) did not provide a description with the name, which is why the authorship of the name was transferred to Gmelin (1791). The year of authorship is 1791, not 1790 as often cited in the literature.	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFEEFF81C099FED3FA214E28.taxon	description	Figures 38, 39	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFEEFF81C099FED3FA214E28.taxon	description	Description: Shell with transverse subangular outline and can have weakly indented front. Both dorsal and ventral valves with weak median furrow. Hinge line wide and straight. No ornamentation except for growth stops. Colour white, yellow or grey. Pedicle opening large and extending into dorsal valve. Deltidial plates not meeting. Shell matrix endopunctate. Brachial loop in dorsal valve long, simple, bilobed and anteromedially fixed. Triangular dorsal median septum sometimes with pillar-like anterior thickening. Median septum also developed in ventral valve, though smaller. Maximum shell length 3 mm. Depth range: 2 – 255 m depth (Logan et al. 1997; Gaspard 2003). However, this species is rarely found deeper than 100 m. Temperature range: 11 – 13 ˚ C (Simon & Willems 1999). Substrate: On bedrock, stones, sand or shells (Jeffreys 1863; this study).	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFEEFF81C099FED3FA214E28.taxon	distribution	Geography: Norway (Vestland, Møre and Romsdal, Trøndelag), East Shetland, Scotland, the Hebrides, Ireland, the English Channel, SE France, Spanish Bay of Biscay, Portugal, Sardinia, Aegean Sea, Sicily, Adriatic Sea, Greece, and the Azores (Jeffreys 1863; Friele 1873; Davidson 1887; Logan 1979; Brunton & Curry 1979; Besteiro & Urgorri 1986; Logan et al. 1997; Thomsen & Brattegard 1997; Simon & Willems 1999; Logan et al. 2007; Bitner & Gerovasileiou 2021; this study). From Norway, it has also been reported from Østfold, Nordland and Troms by Thomsen & Brattegard (1997), but despite searching, no specimens were encountered in the present study to support this. One empty shell was taken from Rogaland in SW Norway during the present study, suggesting its presence there.	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFEEFF81C099FED3FA214E28.taxon	discussion	Comment: This species was first named by Wood (1840); however, as pointed out by Jeffreys (1863), neither a description nor an illustration was provided with the name. Due to the lack of a description, the naming is not a true one in the sense of the International Code of Zoological Nomenclature (Article 12); therefore, it is here assigned to Forbes & Hanley (1849), who provided the first description. Argyrotheca cistellula is uncommon in samples from Norway but seems to prefer shallow waters. Although the species is undoubtedly uncommon, its small shell size additionally makes it easy to overlook.	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFEEFF82C33BFC53FADE4F0B.taxon	description	Figures 40, 41	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFEEFF82C33BFC53FADE4F0B.taxon	description	Figures 42, 43	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFEEFF82C33BFC53FADE4F0B.taxon	description	Description: Shell gently to moderately ventribiconvex. Outline transverse and semicircular with acuminate cardinal extremities to equidimensional subangular, occasionally with weakly indented front. Both dorsal and ventral valves with weak median furrow. Hinge line wide and straight. Ventral umbo typically high and straight. Anterior commissure rectimarginate to unisulcate. Ornament of approximately 8 – 16 coarse, radiating, broadly rounded ribs. Shell white, red or grey, and typically red between ribs. Large round to triangular pedicle opening extending into dorsal valve. Deltidial plates rudimentary. Shell matrix endopunctate. Brachial loop in dorsal valve long, simple, bilobed and anteriorly attached to median septum. Triangular dorsal median septum reaching 4 / 5 valve length with a peak at 2 / 3 valve length. Ventral valve with a distinct median ridge extending to 4 / 5 valve length. Maximum shell length 3 mm. Depth range: 2 – 645 m depth (Logan 1979; Logan 2007). However, from the available data, it seems that this species is mostly found shallower than 60 m. Temperature range: 12 – 20 ˚ C (Brand et al. 2003). Salinity range: 37 – 38 (Brand et al. 2003).	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFEEFF82C33BFC53FADE4F0B.taxon	distribution	Geography: Southernmost Celtic Sea, the Mediterranean, Madeira, the Canary Islands and the Cape Verde Islands (Logan 1979; Brunton & Curry 1979; Simon & Willems 1999; Logan et al. 2007).	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFEEFF82C33BFC53FADE4F0B.taxon	description	Description: Shell typically very uneven, concavoconvex to ventribiconvex, shaping itself after the substratum. Outline circular to transversely oval, but juveniles can be more egg-shaped. Hinge line straight and shorter than greatest shell width. Ornamentation of concentric growth lines, with randomly distributed pustules (tubercles) on ventral valve. Pustules missing on juvenile shells. Shell matrix endopunctate. Colour yellowish-brown or white. Pedicle foramen large and extending well into posterior part of dorsal valve. Deltidial plates narrow. Short brachidium (= lophophoral support) when fully developed, forming a brachial loop supported by short median septum. Median septum very high triangular and can reach slightly anterior of mid-valve length. Very short setae along valve margin. Maximum shell length 8 mm. Depth range: 8 – 2190 m depth (Logan 2007). Temperature range: - 1.2 – 12.0 ˚ C (Carpenter et al. 1869; this study). Salinity range: 35.2 – 35.3 (Thomsen 2001). Substrate: Attached to pebbles, shells and corals (Davidson 1887; Brunton & Curry 1979; Logan 1979; Thomsen 2001). Found on all from mud- to stone-dominated bottoms (Thomsen 2001).	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFEEFF82C33BFC53FADE4F0B.taxon	distribution	Geography: SW of Faroe Islands, Florida, North of Shetland, the Hebrides, Western Approaches, Bay of Biscay, Portugal, Mediterranean, Azores, Morocco, Canary Islands, Cuba, the West Indies, Red Sea, Argentina, South Africa, southernmost S America, Prince Edward Islands, and Antarctica (Fischer & OEhlert 1891, 1892; Cooper 1973 a; Brunton & Curry 1979; Thomsen 2001; Logan et al. 2007, 2008; Zezina 2008).	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFECFF84C33BFBD3FB474828.taxon	description	Figures 44, 45	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFECFF84C33BFBD3FB474828.taxon	description	Description: Shell planoconvex to concavoconvex with dorsal valve almost flat and ventral valve gently convex. Outline subrectangular to transverse oval with very short but pointed beak. Shell surface marked by concentric growth lines. Colour yellowishwhite. Shell matrix endopunctate. Pedicle short. Pedicle foramen large and extending well into posterior part of dorsal valve. Deltidial plates narrow. Short brachidium with an upper transverse band creating a triangular brachial ring supported by and just above median septum. Median septum pillar-like in juveniles, but extending from hinge region to mid-valve length in adults. Setae dense along valve margin and approximately 2 / 3 of the length of the shell. Maximum shell length 5 mm. Depth range: Minimum depth range is 1260 – 2197 m (Lüter 2007). Substrate: Attached to the coral Enallopsammia rostrata (Atkins 1959).	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFECFF84C33BFBD3FB474828.taxon	distribution	Geography: Celtic Sea and the English Channel (Atkins 1959). The species is also reported from the E Pacific (Lüter 2007), but the great distance and oceanographic separation of the populations make it more likely they are two different — though morphologically very similar — species.	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFECFF84C33BFBD3FB474828.taxon	discussion	Remarks: The shells of all type specimens are dissolved, with only periostracum and soft tissue remaining.	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFEBFF85C33BFA10FA0C4A6B.taxon	discussion	Remarks: The validity of the three species Megerlia truncata, M. monstruosa and M. echinata has been a matter of debate for the last nearly 200 years, with many of the greatest brachiopodologists in history taking opposite views. As the issue is still not settled, I feel it is necessary to give an overview of the history of these species. Already, when erecting M. monstruosa, Scacchi (1833) admitted doubt, whether the specimen of his new species in reality was the species M. truncata, which just had shaped itself after the substrate. This opinion of synonymy was shared among others by Costa, Monterosato and Jeffreys based on the internal features, though Jeffreys kept the species as a variety of M. truncata (see: Costa 1838; Monterosato 1872; Jeffreys 1878). Davidson (1887) followed the lead of the others but observed that all specimens he had encountered of M. monstruosa differed in a uniform way from M. truncata, why he chose to keep it as a variety. Subsequently, Fischer & OEhlert (1890) erected a very similar species, M. echinata, mainly differing by having minute spines on the surface. They then followed up by restoring M. monstruosa to species level arguing that while M. truncata often showed deformation due to confinement of substrate, the degree of deformation in shells of M. monstruosa was so extreme and consistent, like the mode of convexity; ornamental characteristics; narrower shell; pedicle opening moved into dorsal valve; the smaller interarea; and the cardinal area on the inside, that they were species-specific (Fischer & OEhlert 1891). Dall (1919 and 1920) found the shared feature of the pedicle opening allocated to the dorsal valve warranted, that M. echinata and M. monstrousa with M. monstruosa as type species were moved into a new genus Pantellaria. Based on observed variability within Megerlia truncata, Thomson (1927) questioned the validity of the suggested generic differences as more than species-level differences. Atkins (1961 a) followed up with a study on M. echinata. There she did not find support for separating this species, but lacking specimens for the study of M. monstruosa, did not suggest transferring that back as well. Most accepted the transfer, though some maintained Pantellaria for M. monstruosa long after (e. g.: Cooper 1981 a, 1982; Zezina 2010, 2014). While noting M. monstruosa externally closely resembled species of the genus Platidia, Logan (1979) again put M. monstruosa into synonymy with M. truncata, though not providing a discussion on why. Comparing the specimens of M. echinata from Atkins (1961 a) with those of M. monstruosa used by Davidson (1887), Brunton (1988) disagreed on this synonymy and argued that M. monstruosa and M. echinata were synonymous though distinct from M. truncata. He thus placed them under the senior name M. monstruosa, an opinion which was followed by Anadon (1994). His study seems to be rather unique in that it directly compared the two species and did not just give a discussion on how each of them differed from M. truncata. Just two years later, Bitner (1990) published a study on 13 – 16 million-year-old Middle Miocene Polish fossils. Though she did not find specimens fully resembling M. echinata and M. monstruosa among her more than 2500 specimens, she did have intermediate specimens and thus concluded, that all three species were one and the same. In general, I hesitate to put too much weight on using the shell morphology of so old specimens as a proof of species synonymy of living brachiopods. This is because 15 million years is a very long time for a species, and both the morphology, and the degree of morphological variability, can change significantly over such a time span, as well as that species can split up in a shorter time (e. g.: Sheldon 1987; Wei & Kennett 1988). Nonetheless, this publication became an important basis for changing the major opinion towards the existence of only one species. Interestingly, in a simultaneous study on nearly 1000 specimens from the same Polish deposits, Barczyk & Barczyk (1990) came to the opposite conclusion, that they had two distinct species, M. truncata and M. monstruosa. Barczyk & Barczyk (1990) found the differences so distinct and ontogenetic stable, that they preferred to follow the opinion of generic division of the two species. With supporting observations of recent morphologically intermediate specimens, Logan et al. (2004) agreed with Bitner (1990) that evidence points to M. monstruosa being conspecific with M. truncata, though they recognized it as a variety and accepted M. echinata as a valid species. This opinion on synonymy was followed by Anadon et al. (2022), Logan (2007), and Logan et al. (2007, 2008). Others, like Alvarez & Emig (2005), Hiller et al. (2008), Alvarez (2016) and Emig (2016), were more inclined to agree with Bitner (1990) in that all three species are synonymous. Trying to give a better basis for comparison, Simon et al. (2016) provided SEM pictures of the holotype of M. echinata together with a discussion. They found the nature of the micro-ornament differed from that of M. truncata, why they concluded M. echinata is a valid species distinct from M. truncata. At present, it seems that the greater majority consider both M. monstruosa and M. echinata synonymous with M. truncata, while a large minority consider M. echinata a valid species. The division in the present work is based on the following reasoning. On a general basis when assuming two species are synonymous, it would be expected that the various features show more intermediate forms as of the type form of the least common form group. Similarly, it would seem unlikely to encounter a relatively consistent combination of seemingly uncorrelated features differentiating two subgroups within the species if no external barriers keep populations separate over an extended time. Going through the available material of the genus, there turned out to be two distinct form groups for which I did not manage to find intermediates among the probable nearly 1000 specimens I have seen. The biggest group contained specimens rather conservatively biconvex and unisulcate, with the major part of the pedicle opening in the ventral valve, and with both valves exhibiting dense, finely costellate ribs as well as low tubercles. Deformation in these specimens appeared only to occur in cases where the specimens had been cramped by substratum or damaged during life. This form group has the typical shape of M. truncata. The smallest group contained the specimens with dorsal valve typically nearly plane to concave, shaping itself after the substratum and rarely showing any hint of ornament other than growth lines; a convex ventral valve with sparse and uneven, weak costellae with scattered tubercles, as well as variably developed minute and alveolate thorns and spines; and a pedicle opening moved almost entirely into the dorsal valve in mature specimens. Specimens still attached to their substrate, showed that the odd shape was not due to confined space or shell damage during life. The shape and the minute spines place this form group as M. echinata. I was unable to find any evidence of external reasons for the general shape of the specimens of M. echinata. I thus find myself in support of the opinion, that M. echinata is not synonymous with M. truncata, and therefore chose to keep them separate in this publication. Another observation from this study was how unevenly distributed the minute thorns and spines were developed on the ventral valve of many of the examined specimens in the form group of M. echinata. These spines were evenly and densely distributed on some valves, while only present on parts of valves or nearly lacking on others. Specimens lacking these spines fit in both shape and ornamentation the description of M. monstruosa and I therefore feel inclined to think that Brunton (1988) and Anadon (1994) were right in that the two species are synonymous rather than M. monstruosa with M. truncata. However, I here realise there are strong opinions to the contrary, and as I have not seen the type specimen of M. monstruosa, I leave this question for others to clarify. If, however, the two species turn out to be synonymous, the name M. monstruosa is the senior synonym.	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFEAFF87C33BF893FD494928.taxon	description	Figures 46, 47	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFEAFF87C33BF893FD494928.taxon	description	Description: Shell low, ventribiconvex to concavoconvex and typically taking shape after the substrate that the dorsal valve is lying on. Adult specimens transverse oval to subrectangular. Umbo blunt and very broad. Narrow and slightly unisulcate anterior commissure in less deformed adults, but rectimarginate in juveniles. Hinge line straight. Narrow deltidial plates not joined. Very large and subcircular pedicle opening almost entirely located in dorsal valve. Ornamentation on ventral valve of generally widely spaced, unequal, uneven, fine and rather poorly defined costellae with scattered tubercles. Minute alveolate thorns or spines usually on and between costellae, though often unevenly distributed and may be lacking entirely. Surface of dorsal valve usually just marked by coarse growth lines, but very weak and sporadic costellae may occur. Shell matrix endopunctate. Colour yellow or white. Dorsal interior with long brachial loop reaching 2 / 3 valve length and supported by median septum. Lophophoral filaments approximately as long as or longer than 1 / 2 shell length. Dorsal septum extending to approximately mid-valve length of shell. Inner surface of valves with radiating lines of tubercles, especially strongly developed in a broad submarginal rim. Maximum shell size 13.5 mm long and 18.5 mm wide. Depth range: 10 – 2780 m depth (Koskeridou 2007; Logan 2007). However, after excluding geographically isolated reports and certain misidentifications of the species, the depth range narrows to 128 – 2780 m, making it a moderately deep- to deep-water species (Koskeridou 2007; Simon et al. 2016; Anadón et al. 2022). Temperature range: 9.5 – 13.6 ˚ C (this study). Substrate: Attached to corals (Dendrophyllia ramea and Desmophyllum pertusum) or shells (Costa 1838; Fischer & OEhlert 1891; Massy 1916; Atkins 1961 c). This species usually seems to be associated with corals.	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFEAFF87C33BF893FD494928.taxon	distribution	Geography: Along the shelf edge of the Celtic Sea and the Bay of Biscay, off Portugal and West Sahara, as well as in the Mediterranean Sea (Jeffreys 1878; Fischer & OEhlert 1890; Massy 1916; Dall 1920; Atkins 1961 c; Gaspard 2003). Observations were also reported from Florida, the Caribbean, the Cape of Good Hope, the Red Sea and SE Australia (Dall 1920; Cooper 1981 b; Logan et al. 2008); however, those from the Red Sea were later recognised as a new species within another genus by Simon et al. (2016), while the remainder are more likely representatives of other species.	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFEAFF87C33BF893FD494928.taxon	discussion	Remarks: See the above remarks for the genus concerning synonymy for the species. The present study was based mostly on the collection housed at the Natural History Museum of London, including numerous specimens of M. truncata and many specimens and even populations assigned to both M. echinata and M. monstruosa.	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFE8FF88C33BFF73FA184CA8.taxon	description	Figures 48, 49	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFE8FF88C33BFF73FA184CA8.taxon	description	Description: Shell resembling Megerlia echinata but differs in the following features. Shell low and biconvex with rather sharp dorsal sulcus and corresponding fold in ventral valve. Adult shells with sharply sulcate anterior commissure. Ornamentation of dense, subequal and fine costellate ribs on both valves, typically with low tubercles along rib crests and with growth lines and stops. Higher tubercles can develop posterolaterally on ventral valve. The radiating ornamentation and tubercles are strongest on ventral valve. Tubercles always situated on rib crests. Shell less often markedly deformed from attachment to substrate. Longest filaments in lophophore shorter than half shell length. Maximum shell length 20 mm. Depth range: 8 – 1086 m depth (Logan 2007), but since Megerlia echinata is broadly synonymised with the species, the range is somewhat uncertain. When restricting to confirmed specimens from the Mediterranean and NE Atlantic region, the range is 16 – 586 m depth (Fischer & OEhlert 1891; Anadón et al. 2022). Temperature range: 11.5 – 19 ˚ C (Jeffreys 1878; Brand et al. 2003). Salinity range: 37 – 39 (Brand et al. 2003). Substrate: Attached to corals (Dendrophyllia corniger), shells, artificial substrates or rocky substrates (Gray 1853; Atkins 1961 c; Koskeridou 2007; Toma et al. 2022).	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFE8FF88C33BFF73FA184CA8.taxon	distribution	Geography: Coast of Brittany in W France, Bay of Biscay, Portugal, Azores, the Mediterranean, the Canary Islands, and Cap Blanc in Mauritania (Jeffreys 1878; Fischer & OEhlert 1891). The specimen collected by Turton and identified as Megerlia truncata from off Torquay / Torbay in S England was, according to Jeffreys (1878), needing verification. However, Dall (1920) maintained the identification. No other specimens appear to have been collected since. Zezina (2014) listed it from the mid-Atlantic ridge Reykjanes Ridge at 58 ˚ 23 ’ N south of Iceland, which requires verification.	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFE8FF88C33BFF73FA184CA8.taxon	discussion	Remarks: When synonymising the two species Anomia truncata Linnaeus, 1767 and Anomia scobinata Linnaeus, 1758, the name Anomia scobinata was mistakenly attributed to Gmelin (1791) (e. g., Dall 1870, 1873). Thus, Anomia truncata was given seniority. According to the International Code of Zoological Nomenclature (Article 23) the senior name should normally be given precedence. However, Article 29.3 states that prevailing usage must be followed when the senior synonym has not been used as a valid name after 1899, and the junior synonym has been used for a particular taxon, as its presumed valid name, in at least 25 works, published by at least 10 authors in the immediately preceding 50 years and encompassing a span of not less than 10 years. In the present case, the demands for the exception are fulfilled, while the name A. truncata Linnaeus, 1767 is given precedence over A. scobinata Linnaeus, 1767. In their study on Kraussinid brachiopods, Simon et al. (2016) questioned the worldwide distribution previously attributed to the species and argued that true M. truncata are restricted to the Mediterranean and the Lusitanian Province of the Eastern Atlantic.	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFE7FF8AC338FD13FCE44CA8.taxon	description	Figures 1 E, 1 G, 50, 51	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFE7FF8AC338FD13FCE44CA8.taxon	description	Description: Shell longer than wide (L / W ratio: 1.06 – 1.56; mean: 1.20), and moderately to strongly biconvex. Adult shells with pentagonal to subtriangular outline and widest in anterior portion of shell. Juvenile specimens with egg-shaped outline, though typically with weakly truncated front. Umbo short and stubby in adults, but somewhat narrow in juveniles. Anterior commissure changing from rectimarginate in juveniles, over broadly unisulcate, to distinctly parasulcate in adult specimens. Lateral commissure is straight to gently curved. Shell surface as a rule smooth except for sporadic growth lines, but large specimens can show sporadic radiating weak striation resembling that of Hemithiris. Shell white or straw-coloured. Shell matrix endopunctate. Circular, rather large and usually slightly transverse pedicle foramen developed in specimens over 6 mm long, but subtriangular to triangular deltidial plates disjunct in smaller specimens. Deltidial plates not separated from rest of shell by distinct beak ridges, but typically forms a raised ridge along midline when conjoined. Pedicle collar (thickening in pedicle tube) very short and lacking in juveniles. Ventral teeth never supported by dental plates. Hinge plates extended forward to join dorsal median septum in a V-shape. Brachial loop long and with wide transverse band. Brachial loop not attached to median septum on specimens longer than 13 mm. Long and low dorsal median septum reaches 60 – 84 % of valve length, except in juvenile specimens, and visible as a whitish knife-cut line on dorsal valve exterior. Juvenile specimens below 1.65 mm long lack dorsal median septum. A short septum with dot-shaped basis later evolves, which very soon becomes knife-cut shaped. Spicules in tissue mostly absent. Maximum shell length 45 mm. Depth range: 37 – 1800 m depth (Fischer & OEhlert 1892; this study), but common between 180 – 800 m. Temperature range: - 1.1 – 10.2 ˚ C (Carpenter et al. 1869; Jeffreys 1878). Salinity range: 34.9 – 36 (Thomsen 2001; Brand et al. 2003). Substrate: Attached to sand, gravel, corals, shells, bryozoans, serpulid tubes or Foraminifera (Atkins 1960 a; Thomsen 2001; this study). Sea bottom varies from silt- and sand-dominated to stony (Thomsen 2001).	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFE7FF8AC338FD13FCE44CA8.taxon	distribution	Geography: Southwestern-most Barents Sea and south along the Norwegian coastline to Hordaland, northernmost North Sea, NE Atlantic S of Iceland, and along the W part of the British Isles (Lovén 1846; Fischer & OEhlert 1891, 1892; Wesenberg-Lund 1939, 1941; Atkins 1960 a; Thomsen 2001; this study). The southern border of the species is uncertain since the southernmost verified specimen is from Scotland. However, Dallina septigera seems to be absent from the southern margin of the Celtic Sea.	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFE7FF8AC338FD13FCE44CA8.taxon	discussion	Remarks: In his original description of Dallina septigera, Lovén (1846) did not provide illustrations. Likely for this reason, subsequent researchers simply assumed French and Spanish specimens belonged to the same species and adjusted the species description accordingly. In contrast to the strongly triangular outline of the following species, the true D. septigera is normally subpentagonal in outline. The geographical boundary between the two species appears to be on the W side of Great Britain. In her redescription of D. septigera, Atkins (1960 b) did not realise that the genus included two European species, and thus based her redescription almost solely on the material of Dallina lusitanica n. sp., assuming the differences between the single available Norwegian specimen and the remaining material were intraspecific differences. In his study on material from France, Cooper (1981 a) stated that the species could usually be distinguished from the morphologically close species Fallax dalliniformis by its triangular shape with its greatest width at the front when compared to the typically more subpentagonal outline with its greatest width a bit further back on the other species, thus showing that the specimens from France were representatives of the new species and not D. septigera. A comparison with Fallax dalliniformis is provided in the discussion of that species. Subadult and juvenile specimens are often mistaken for Macandrevia cranium but are distinguished by the earlier development of the dorsal median septum (which rapidly becomes long) and by the absence of bordering ridges along the deltidial plates. There are presently no indications that this species is negatively influenced by ongoing ecological changes within the Norwegian region.	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFE5FF8CC33BFDD3FBA34EA8.taxon	description	Figures 52, 53	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFE5FF8CC33BFDD3FBA34EA8.taxon	materials_examined	Type locality: Southernmost Celtic Sea, off France, 47 ° 11 ’ – 47 ° 14 ’ N, 6 ° 11 ’ – 6 ° 13 ’ W, 1143 m depth.	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFE5FF8CC33BFDD3FBA34EA8.taxon	etymology	Etymology: After the Lusitanian marine region of the temperate Northern Atlantic realm, in which the species mostly occurs.	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFE5FF8CC33BFDD3FBA34EA8.taxon	diagnosis	Diagnosis: Moderately large Dallina species. Mature specimens characterised by their typically strongly subtriangular outline with greatest width close to anterolateral corners. Lateral commissure distinctly curved and anterior commissure gently to moderately parasulcate. Dorsal septum extended to approximately 80 – 90 % of valve length.	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFE5FF8CC33BFDD3FBA34EA8.taxon	materials_examined	Material: Holotype: Celtic Sea, 47 ° 11 ’ – 47 ° 14 ’ N, 06 ° 11 ’ – 06 ° 13 ’ W, 1143 m depth, one specimen, BMNH PI ZB 4948. Paratypes: Celtic Sea, 47 ° 37 ’ N, 07 ° 27 ’ W, 722 m depth, eight specimens, BMNH PI ZB 4955 – 4962; Celtic Sea, 48 ° 06 ’ – 48 ° 26 ’ N, 09 ° 18 ’ – 09 ° 44 ’ W, 977 m depth, one juvenile ventral valve, BMNH PI ZB 4946; Celtic Sea, 48 ° 32 ’ – 48 ° 33 ’ N, 10 ° 09 ’ – 10 ° 10 ’ W, 686 – 896 m depth, 14 specimens BMNH PI ZB 4944 – 4945, 4951 – 4953, 4963, 4967 – 4969, 4972, 4973, 4977; Celtic Sea, 48 ° 38 ’ – 48 ° 39 ’ N, 09 ° 45 ’ – 09 ° 50 ’ W, 933 – 1061 m depth, one specimen, BMNH PI ZB 4970;? Celtic Sea (from study material of D. Atkins), seven specimens, BMNH PI ZB 4953, 4964 – 4966, 4971, 4976; Celtic Sea, 47 ° 11 ’ – 47 ° 14 ’ N, 06 ° 11 ’ – 06 ° 13 ’ W, 1143 m depth, one damaged ventral valve kept together with holotype.	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFE5FF8CC33BFDD3FBA34EA8.taxon	description	Description: Shell moderately to strongly biconvex. Outline variable, but adult shell normally with subtriangular to strongly triangular outline, and widest typically at or very close behind anterolateral corners. L / W ratio 0.94 – 1.37 with mean of 1.15. Juvenile specimens with more egg-shaped outline. Umbo short and stubby. Anterior commissure changing from rectimarginate in juveniles, over broadly unisulcate, to strongly parasulcate. Lateral commissure usually moderately curved in adults. Anterior part of dorsal valve typically with two very pronounced folds along the flanges. No ornamentation besides growth lines. Shell somewhat translucent, fragile and white with a thin yellowish periostracum often peeling in stored specimens. Shell matrix endopunctate. Egg-shaped subcircular and rather large pedicle foramen. Deltidial plates fused to form a symphytium, often with a raised longitudinal ridge. Deltidial plates well-defined, but not separated from rest of valve by ridges. Pedicle collar (thickening in pedicle tube) very short. No dental plates supporting ventral teeth. Descending lamellae of brachial support thin and gently diverging and joined by broad transverse band to form a long loop. Brachial loop not attached to median septum at least on specimens longer than 17 mm. Long and low dorsal median septum usually extends to 80 – 91 % of valve length (a few dorsal valves below 21 mm length with septum down to 51 % of valve length), and always visible as a whitish knife-cut line on dorsal valve exterior. Spicules in tissue mostly absent. Maximum shell length 30 mm. Depth range: 460 – 3000 m depth (Logan 1998; Anadón et al. 2022), but mostly between 600 – 1500 m. Temperature range: Based on three stations 7.0 – 9.5 ˚ C (this study). Substrate: Typically found on mud- or fine sand-dominated bottoms, very often in connection with hard corals and coral debris, where it is found attached to corals, shells, gravel and stones (Joubin 1907; Anadón 1994; Anadón et al. 2022; this study).	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFE5FF8CC33BFDD3FBA34EA8.taxon	distribution	Geography: Celtic Sea, Bay of Biscay, NE Atlantic, Portugal, Azores and Canary Islands. This species most likely has its northern border at the Celtic Sea, but a systematic examination of the Irish Dallina specimens is required to clarify this.	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFE5FF8CC33BFDD3FBA34EA8.taxon	discussion	Remarks: Dallina lusitanica n. sp. is smaller and more fragile, subtriangular to strongly triangular with the greatest width typically at or close to the anteroventral corners, and with distinctly curved lateral commissure in contrast to Dallina septigera, which is more solid, pentagonal to subtriangular with the greatest width mostly located well behind the anterolateral corners, and with the main part of the lateral commissure nearly straight. Among the 10 species included in the genus, this new species most closely resembles Dallina floridana (Pourtalès, 1868) and Dallina triangularis Yabe & Hatai, 1934. However, the approximately 28 mm long species Dallina floridana (known from Florida, the Gulf of Mexico and the West Indies) is generally as wide or wider than long, with the dorsal septum reaching 64 – 76 % of valve length, anterior commissure more strongly parasulcate and a ventral umbo that is more strongly curved. Based on descriptions and five new shells from the Philippines’ Balut Island housed at the Arctic University Museum of Norway, the up to 32.5 mm long Dallina triangularis known from Japan, the South China Sea and Fiji differs by having a shorter dorsal septum reaching 70 – 80 % of valve length, typically being much more strongly parasulcate, with a shell matrix markedly thinner around the foramen, dorsal umbo markedly more acute and lateral ridges on ventral valve diverging increasingly at the front on adult shells, giving the valve a bell-shaped outline (Yabe & Hatai 1934; Hatai 1940; Bitner 2008, 2019; this study). Atkins (1960 b) redescribed Dallina septigera largely based on the material of the present species whilst assuming the observed variations were intraspecific. Also, Cooper (1981 a) and Anad ó n et al. (2022) used the diagnostic external features of the new species to distinguish what they thought were D. septigera from the morphologically close species Fallax dalliniformis, suggesting D. septigera is at least nearly absent from France and N Spain. To date, there appears to be very little, if any, overlap in the geographical ranges of these two species.	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFE3FF8DC33BFB33FC034BA8.taxon	description	Figures 54, 55	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFE3FF8DC33BFB33FC034BA8.taxon	description	Description: Shell inflated biconvex. Outline of adult shells triangular to distinctly truncated subpentagonal and widest close to front. Small specimens with more egg-shaped outline. Ventral umbo beak-shaped, curved and acute in profile. Anterior commissure normally parasulcate. Shell surface marked by growth lines. Shell matrix endopunctate. Colour whitish to slightly brownish, but older shells often with brownish secondary colour. Deltidial plates disjunct in specimens below 10 mm long, but then joining and restricting pedicle opening to a relatively small and egg-shaped foramen. Long pedicle collar (raised shell matrix in umbo). Short dental plates supporting strong hinge teeth. Hinge plates not extended forward to form a V-shape at connection with dorsal median septum but meet it in a right angle or with median indention. Long brachial loop with wide transverse band and supported by median septum. Long, low dorsal median septum reaching to 2 / 3 – 15 / 16 valve length and always visible as whitish knife-cut line on dorsal valve exterior. Abundant spicules in soft tissue (can disappear when stored too long in ethanol). Maximum shell length 29.7 mm. Depth range: 702 – 2100 m depth (Anadón 1994; Anadón et al. 2022). Although Brunton & Curry (1979) gave a depth range starting from 210 m, the origin of that figure is uncertain. Substrate: Attached to rocks, shells or corals (Atkins 1960 a).	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFE3FF8DC33BFB33FC034BA8.taxon	distribution	Geography: Celtic Sea and Bay of Biscay (Atkins 1960 a).	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
03D43D5BFFE3FF8DC33BFB33FC034BA8.taxon	discussion	Remarks: This species is externally very similar to the two Dallina species. However, the ventral umbo is curved and beak-shaped with an egg-shaped foramen, the pedicle collar is long, the ventral hinge teeth are supported by dental plates and the brachial loop is always supported by the median septum. Juvenile specimens may easily be confused with the species Glaciarcula spitzbergensis, which has previously led to the assumption that this subarctic and Arctic species was present in waters around Spain and the Scilly Isles (see discussion for Glaciarcula spitzbergensis). However, juveniles of Fallax dalliniformis can be externally distinguished by a less elongated pedicle opening, broader outline with the early development of anterior truncation, and thinner shell wall.	en	Hansen, Jesper (2024): Brachiopods of the Norwegian fauna northern North Atlantic and Arctic, with a focus on. Fauna norvegica 43: 12-68, DOI: 10.5324/fn.v43i0.5110, URL: https://doi.org/10.5324/fn.v43i0.5110
