Vosmaeria crustacea Fristedt, 1885

Gerasimova, Elena, Erpenbeck, Dirk & Plotkin, Alexander, 2008, Vosmaeria Fristedt, 1885 (Porifera, Demospongiae, Halichondriidae): revision of species, phylogenetic reconstruction and evidence for split, Zootaxa 1694, pp. 1-37 : 6-15

Vosmaeria crustacea Fristedt, 1885

Synonymy:

Vosmaeria crustacea – Fristedt, 1885: 24, pl. II figs. 5a–d; Rezvoj, 1928: 81; Burton, 1930: 496; Arndt, 1935: 37, fig. 60; Alander, 1942: 76; Koltun, 1966: 91, pl. XXIV figs. 5–6, text-fig. 62.; Erpenbeck & van Soest, 2002: 815, figs. 18d–g.

Inflatella ? sp. – Vosmaer, 1885: 21, pl. 5 figs. 17–19.

Inflatella crustacea – Levinsen, 1893: 414.

Vosmaeria robusta – Swarczewsky, 1906: 320, pl. 14.

Inflatella robusta – Breitfuss, 1911: 219.

Type material:

Type series identified by Fristedt (1885) was collected near Bohuslän, western Swedish Coast (Skagerrak Straight, North Sea). Fristedt did not designate a holotype. SMNH Type N 1686a (fig. 1A) is here designated as the lectotype because it was collected by Fristedt himself and the locality written on the original label (Bohuslän, Gullmaren) corresponds to the information given in his publication. The remaining four specimens (figs. 1B-E) and one fragment in the type series are designated as paralectotypes.

Lectotype (here designated): SMNH Type N 1686a (dry specimen): Bohuslän, Gullmaren; 54–125 m; date unknown; collector K. Fristedt. Paralectotypes: SMNH Type NN 1686b,c (1 whole dry specimen and 1 small dry fragment, respectively): same locality as lectotype. SMNH Type N 1198a,b (2 specimens in alcohol): Bohuslän, Gullmarsfjord, Kristineberg; depth unknown; 1879; collector H. Theel. SMNH Type N 1208 (1 specimen in alcohol): Bohuslän; depth unknown; 1876; collector K. Fristedt.

Additional material used for morphological studies (all fixed in 70% alcohol):

Murman Coast, Barents Sea: ZIRAS N35a (1 specimen): Kildin Straight; 100 m; bottom–shells, silted sand, stones; 25.07.1884; Expedition of Herzenstein; st. 66. ZIRAS N 36a/5626 (1 specimen): Arsky Bay; depth unknown; bottom–stones, silt; 26.06.1884; Expedition of Herzenstein; st. 50. ZIRAS N 77/5624 (1 specimen): 69° 22' N – 32° 56' E; 210 – 270 m; bottom–silt; 23.08.1900; r/v ‘St. Andrew Pervozvanny’; st. 312; Petersen trawl N 718. ZIRAS N 81 (1 specimen): Kola Bay; depth unknown; 7.08.1913; collector K.M. Derjugin. ZIRAS N 85a/5627 (1 specimen): 69° 45' N – 31° 09.5' E; 71 m; bottom–stones; 16.08.1900; r/v ‘St. Andrew Pervozvanny’; st. 307; dredge N 710. ZIRAS N 89 (1 specimen): Motka Bay; 60–100 m; date unknown; collector Jarzhinsky.

Kandalaksha Bay, White Sea: ZIRAS N 1/20968 (1 specimen): 66°52.7' N – 32°30' E; 18 m; bottom– sand, gravel; 26.08.1961; r/v ‘Professor Mesyatsev’; st. 803(9); collector Kunin. AP Por N 66 (1 specimen): Chupa Inlet, Sel'dyanaya Harbour, 66°20.129' N – 33°37.6' E; 15 m; bottom–silt, stones; 02.07.2001; collectors E. Gerasimova & A. Plotkin. AP Por NN 408, 409, 410, 416 (4 specimens): Keret' Inlet, Podpakhta Straight; 66°18.161' N – 33°37.896' E; 15–17 m; bottom–silt, pebbles; 27.07.2001; collectors E. Gerasimova & A. Plotkin.

Onega Bay, White Sea: ZIRAS N 4/21052 (1 specimen): Cape Listvenny; 27 m; bottom–silted sand, pebbles, gravel; 29.07.1982; White Sea expedition of the Zoological Institute, Russian Academy of Sciences; transect 5, st. 2/2; collector Golikov. ZIRAS N 29a (1 specimen): 65°10' N – 35°02.3' E; 65 m; bottom–gravel; 18.10.1964; r/v ‘Professor Mesyatsev’; st. 1155(2); collector Kunin. ZIRAS N 32a (1 specimen): 65°09.8' N – 35°02' E; 59–60 m; bottom–gravel, sand; 29.06.1961; r/v ‘Onega’; st. 2; collector Kunin. ZIRAS NN 73a,b,c (3 specimens): precise location unknown; 43 m; bottom–pebbles; 11.07.1984; Expedition of the White Sea Biological Station of Moscow State University; st. 503(D-1); collector N.L. Semyonova.

Material used for molecular analysis (all fixed in 96% alcohol):

Kandalaksha Bay, White Sea: AP Por N 339 (2 specimens): Keret' Inlet, Sredny Island; 66°17.391' N – 33°38.025' E; 10–14 m; bottom–vertical rock; 1.06.2003; collectors Gerasimova & Plotkin. AP Por N 260 (5 specimens): Keret' Inlet, Podpakhta Straight; 66°18,161' N – 33° 37,896' E; 10–20 m; bottom–ferro-manganous concretions with silt; 2.06.2003; collectors E. Gerasimova & A. Plotkin.

Description:

External characters

Dry lectotype an encrusting, irregular shaped sponge, approx. 21 mm long, 11 mm wide, 2 mm thick (fig. 1A). Surface light brown, smooth, with 22 cone-like sharply pointed white papillae, 2–4 mm long, about 1 mm in basal diameter. The largest examined specimens up to 5.5 cm 2 in square with more than 80 papillae (fig. 1F). Mean concentration of papillae 15±1 per cm2 of surface. Surface of living specimens usually brown due to the agglutinated sediments and often covered by foraminiferans. Ectosome firm and dense, hardly detachable from choanosome. The latter faintly beige. Papillae whitish and semitransparent, 0.5–8 mm in height, 0.1–1.2 mm in basal diameter. Discrimination between inhalant and exhalant papillae impossible by a naked eye, or under low magnification.

Skeleton

Choanosomal skeleton constituted by dense tracts of (sub)tylostyles (140–300 µm thick) running from the sponge base through the choanosome, and forming the sheath framework of the papillae (fig. 2A). Free tylostyles and oxeas randomly scattered between the principal tracts. Skeleton of the sponge base consists of a dense, confused spicule mass (fig. 2B). Ectosomal skeleton very firm, 300–600 µm in thick, constituted mainly by oxeas and a smaller amount of tylostyles lying tangentially to the surface (fig. 2C). Ectosomal areas close to the papillae contain also oxea-derived styles.

Aquiferous system

Walls of inhalant papillae perforated by ostia mainly in their apical part (fig. 3A). Ostia 5–11 µm in diameter, connected by short transversal canals, and with a central inhalant canal (diameter from 20–40 µm at the upper part of the papilla, up to 200–350 µm in its base). The latter branches beneath the ectosome into several thinner canals, running into the choanosomal inhalant aquiferous cavities, from which the water flows to the choanocyte chambers (20–35 µm in diameter) along numerous canals. The exhalant canals run from the choanocyte chambers to the large choanosomal exhalant atriums, opening in the single central canal of the exhalant papilla (fig. 3B), which terminates in an osculum. The diameter of the central exhalant canal varies from 250–500 µm at the papilla base, to 50–230 µm at its upper part.

Spicules (means in parentheses)

-(Sub)tylostyles (fig. 4): Altogether, 720 tylostyles observed (30 spicules in each specimen). In the lectotype all observed tylostyles with both tips rounded, and the tyles usually well developed and moderately displaced from the proximal tips of spicules (table 2). Two spicules had one additional tyle. Most tylostyles slender and slightly curved. Measurements (table 3): length 610–955 µm (809 µm), proximal diameter 7.5– 17.5 µm (13.8 µm), diameter of tyle 12.5–18.8 µm (16.4 µm), central diameter 7.5–20 µm (14.1 µm), distal diameter 2.5–7.5 µm (5 µm).

In other specimens: 63% of all observed tylostyles slender and 37% fusiform; more than 73% straight, about 22% slightly curved, 4% moderately curved and approx. 1% considerably curved; near 99% with both tips rounded and about 1% with acerate distal tips; 95% with well developed tyles, less than 5% with weakly developed tyles and 0.3% have no tyle: approx. 13% with terminal tyles, 46% with slightly displaced tyles, 29% with moderately displaced tyles and about 11% with considerably displaced tyles; about 1.5% with one additional tyle and 0.6% with two additional tyles (table 2). Measurements (table 3): length 260–1130 µm (688 µm), proximal diameter 3.8–23.3 µm (12.7 µm), diameter of tyle 7.5–28.3 µm (15.7 µm), central diameter 3.8–26.7 µm (13.8 µm), distal diameter 0–15 µm (4.9 µm). Tylostyles cannot be divided into separate size classes as their frequency distribution is close to normal (fig. 6A).

Abbreviations: Curvature: S–straight, SC–slightly curved, MC–moderately curved, CC–considerably curved; Slenderness: F–fusiform, SL–slender; Tyle development: A–absent, WK–weakly developed, WL–well developed; Tyle location: T–terminal, SD–slightly displaced, MD–moderately displaced, CD–considerably displaced.

(Sub)tylostyles Oxeas Curvature Slender- Tyle develop- Tyle location Curvature ness ment

-Oxeas (figs. 5A–C; E–F): Altogether, 720 oxeas observed (30 spicules in each specimen). In the lectotype all oxeas with acerate tips, most slightly curved (table 2). Measurements (table 3): length 610–1010 µm (815 µm), central diameter 17.5–32.5 µm (24.3 µm).

In other examined specimens: most oxeas with acerate tips (fig. 5A–B; E) and very few with blunt tips (fig. 5C; F); majority smooth, while 1,1% centrotylote; about 17% of all observed oxeas straight, 68% slightly curved, 14% moderately curved and less than 1% considerably curved (table 2). Measurements (table 3): length 340–1100 µm (690 µm), central diameter 7.5–50 µm (23.5 µm). Oxeas cannot be divided into separate size classes as their frequency distribution is close to normal (fig. 6B).

-Oxea-derived styles (fig. 5D): Altogether, 129 styles observed. No styles found in the specimens SMNH Type N 1686b and ZIRAS N 73b. In the lectotype two styles examined (table 3), both straight with acerate distal tips. One style fusiform, with a well developed slightly displaced tyle, length 890 µm, 15 µm in proximal diameter, 16.3 µm in central diameter. The other style slender, with no tyle, length 630 µm, 25 µm in both diameters.

In other examined specimens: 67% of all observed styles fusiform and 33% slender; 53% straight, 36% slightly curved and about 9% moderately curved; majority with acerate distal tips while five styles with blunt tips; about 66% without tyles, approx. 20% with well developed and 14% with weakly developed tyles. Measurements (table 3): length 230–930 µm (571 µm), proximal diameter 5–48.3 µm (17.9 µm), central diameter 7.5–48.3 µm (22.8 µm).

All measurements are given in μm. Each measurement is given as minimum-mean-maximum. 30 oxeas and 30 (sub)tylostyles were measured for each specimen. Number of measured styles is given at the end of the lower row as n. Length is given in the upper row; diameter is given in the lower row. Diameter of tylostyles is given as proximal diameter / central diameter / distal diameter. Diameter of styles is given as proximal diameter / central diameter.

Specimen Region (Sub)tylostyles Oxeas Oxea-derived styles SMNH Type Skagerrak 560-872-1060 420-883-1100 600-752-930

N 1198a Straight 7.5-14.7-21.3 / 8.8-17.5-23.8 / 0-6.5-10 15-33.8-50 10-23.3-47.5 / 25-36- 47.5 n =5 Distribution and ecology:

North Sea: Skagerrak Straight (type locality, depth 54–125 m); Barents Sea: from the Murman Coast in the South to 74° 50' N in the North (depth 32–270 m); White Sea: Kandalaksha and Onega Bays (depth 10– 120 m) (see map on fig. 9).

Sponges occur mainly at sites with low hydrodynamism on plain silted bottom overgrowing small stones, pebbles, ferromanganese concretions, wood residuals, polychaete tubes and empty bivalve shells; maximum observed density 15 spec./m2, maximum biomass 3 g /m2. More rarely sponges grow on vertical rocks; maximum density 22 spec./m2, maximum biomass 5 g /m2. In both habitats sponges covered with silt with only the papillae protruding, hardly seen by a diver.

Geographical variability of spicules:

Spicule length demonstrated significant dependence on the region (table 4). Both tylostyles and oxeas of the White Sea sponges shorter than those of other specimens (figs. 7A; C). No significant difference in spicule size registered between the North and Barents Sea sponges and between the specimens from the Kandalaksha and Onega Bays within the White Sea. No dependence detected of spicule shape on the geographical locality (fig. 8).