Laevidentalium wiesei Sahlmann, 2012

(SOSA), Senckenberg Ocean Species Alliance, Andrade, Luiz F., Boyko, Christopher B., Brandt, Angelika, Buge, Barbara, Dávila Jiménez, Yasmín, Henseler, Mats, Hernández Alcántara, Pablo, Jóźwiak, Piotr, Knauber, Henry, Marcondes Machado, Fabrizio, Martínez-Muñoz, Carlos A., Momtazi, Farzaneh, Nakadera, Yumi, Qiu, Jian-Wen, Riehl, Torben, Rouse, Greg W., Sigwart, Julia D., Sirenko, Boris, Souza-Filho, Jesser F., Steger, Jan, Stępień, Anna, Tilic, Ekin, Trautwein, Bianca, Vončina, Katarzyna, Williams, Jason D. & Zhang, Junlong, 2025, Ocean Species Discoveries 13 – 27 — Taxonomic contributions to the diversity of Polychaeta, Mollusca and Crustacea, Biodiversity Data Journal 13, pp. e 160349-e 160349 : e160349-

Laevidentalium wiesei Sahlmann, 2012

Laevidentalium wiesei n. spec.: Sahlmann (2012): 26, Plate 6, figs. 1–3; 27, Plate 7, figs. 1 a, 2 a – b, 3 a.

Dentaliida sp. M: Brandt (2022): 157, 158, 166, Tab. 5.26, fig. 5.96; Sigwart et al. (2025): fig. 4 L.

“ deep-sea scaphopod-anemone association ”: Linse and Neuhaus (2024): 14.

Laevidentalium wiesei : Sigwart et al. (2025): tab. 1.

Materials

Type status: Holotype. Occurrence: catalogNumber: HNC 43947 ; individualCount: 1; associatedReferences: Sahlmann, B. (2012) Description of a new abyssal scaphopod, Laevidentalium wiesei , from the Kurile-Kamchatka Trench ( Mollusca, Scaphopoda). Schriften zur Malakozoologie aus dem Haus der Natur – Cismar, 27, 25–28.; occurrenceID: 975F8F10-C2E4-5DEF-9143-CD8AFEBD9439; Taxon: scientificNameID: urn:lsid:marinespecies.org:taxname:716154; scientificName: Laevidentalium wiesei Sahlmann, 2012 ; kingdom: Animalia; phylum: Mollusca; class: Scaphopoda; order: Dentaliida ; family: Laevidentaliidae ; genus: Laevidentalium ; specificEpithet: wiesei ; taxonRank: species; scientificNameAuthorship: Sahlmann; nomenclaturalCode: ICZN; Location: higherGeography: Pacific Ocean; waterBody: Northwest Pacific Ocean, Russian Exclusive Economic Zone, Kuril-Kamchatka Trench area; locality: Kuril-Kamchatka Trench area ; verbatimLocality: RUS / Kurile-Kamchatka Trench; verbatimDepth: 5035-5210 m; minimumDepthInMeters: 5035; maximumDepthInMeters: 5210; verbatimCoordinates: 45°N, 156°E; verbatimLatitude: 45°N; verbatimLongitude: 156°E; verbatimCoordinateSystem: degrees; decimalLatitude: 45; decimalLongitude: 156; Identification: identifiedBy: Bernd Sahlmann; Record Level: language: en; institutionCode: HNC; basisOfRecord: PreservedSpecimen

Type status: Paratype. Occurrence: catalogNumber: HNC 82015 ; individualCount: 1; associatedReferences: Sahlmann B (2012) Description of a new abyssal scaphopod, Laevidentalium wiesei , from the Kurile-Kamchatka Trench ( Mollusca, Scaphopoda). Schriften zur Malakozoologie aus dem Haus der Natur – Cismar, 27, 25–28.; occurrenceID: 930E2C3E-17E1-58BF-807C-D87C0727FBEC; Taxon: scientificNameID: urn:lsid:marinespecies.org:taxname:716154; scientificName: Laevidentalium wiesei Sahlmann, 2012 ; kingdom: Animalia; phylum: Mollusca; class: Scaphopoda; order: Dentaliida ; family: Laevidentaliidae ; genus: Laevidentalium ; specificEpithet: wiesei ; taxonRank: species; scientificNameAuthorship: Sahlmann; nomenclaturalCode: ICZN; Location: higherGeography: Pacific Ocean; waterBody: Northwest Pacific Ocean, Kuril-Kamchatka Trench area; locality: Kuril-Kamchatka Trench area ; verbatimLocality: SU / Kurile-Kamchatka Trench; verbatimDepth: 4500 m; minimumDepthInMeters: 4500; maximumDepthInMeters: 4500; verbatimCoordinates: 41°N, 156°E; verbatimLatitude: 41°N; verbatimLongitude: 156°E; verbatimCoordinateSystem: degrees; decimalLatitude: 41; decimalLongitude: 156; Identification: identifiedBy: Bernd Sahlmann; Event: habitat: abyssal / hadal; Record Level: language: en; institutionCode: HNC; basisOfRecord: PreservedSpecimen

Type status: Other material. Occurrence: catalogNumber: SMF 366425 ; recordNumber: AB- 4794; recordedBy: R / V SONNE AleutBio cruise SO 293; individualCount: 1; preparations: whole animal (EtOH); previousIdentifications: Dentaliida sp. M; associatedReferences: Brandt, A. (2022) (ed.) SO 293 AleutBio (Aleutian Trench Biodiversity Studies). SONNE-Berichte (R / V SONNE cruise reports). 209 pp.; associatedSequences: https://portal.boldsystems.org/record/OSD004-25; occurrenceID: 89137760-8030-5134-B7E4-808F729A9F05; Taxon: scientificNameID: urn:lsid:marinespecies.org:taxname:716154; scientificName: Laevidentalium wiesei Sahlmann, 2012 ; kingdom: Animalia; phylum: Mollusca; class: Scaphopoda; order: Dentaliida ; family: Laevidentaliidae ; genus: Laevidentalium ; specificEpithet: wiesei ; taxonRank: species; scientificNameAuthorship: Sahlmann; nomenclaturalCode: ICZN; Location: higherGeography: Pacific Ocean; waterBody: Northeast Pacific Ocean, U. S. Exclusive Economic Zone, Alaska Region; locality: Aleutian Trench, AleutBio / SO 293 cruise, AleutBio station SO 293 _ 14-10 AGT ; verbatimDepth: 4877 m; minimumDepthInMeters: 4877; maximumDepthInMeters: 4877; verbatimCoordinates: 52°40.90'N, 161°51.71'W to 52°40.90'N, 161°51.72'W; verbatimCoordinateSystem: degrees decimal minutes; Identification: identifiedBy: Jan Steger; dateIdentified: 2024; identificationReferences: Sahlmann, B. (2012) Description of a new abyssal scaphopod, Laevidentalium wiesei , from the Kurile-Kamchatka Trench ( Mollusca, Scaphopoda). Schriften zur Malakozoologie aus dem Haus der Natur – Cismar, 27, 25–28.; Event: eventID: SO 293 _ 14-10 AGT; samplingProtocol: Agassiz trawl, contents sieved through a 1 mm mesh; samplingEffort: 1006 m trawled distance; eventDate: 2022-08 - 29 T 09: 57 Z / 2022 - 08 - 29 T 10: 30 Z; eventTime: 09: 57 Z / 10: 30 Z; year: 2022; month: 8; day: 29; habitat: abyssal sediment; fieldNumber: AB- 4794 | MOL- 1000; Record Level: language: en; institutionCode: SMF; basisOfRecord: PreservedSpecimen

Type status: Other material. Occurrence: catalogNumber: SMF 366426 ; recordNumber: AB- 4794; recordedBy: R / V SONNE AleutBio cruise SO 293; individualCount: 1; preparations: whole animal (EtOH); previousIdentifications: Dentaliida sp. M; associatedReferences: Brandt, A. (2022) (ed.) SO 293 AleutBio (Aleutian Trench Biodiversity Studies). SONNE-Berichte (R / V SONNE cruise reports). 209 pp.; associatedSequences: https://portal.boldsystems.org/record/OSD005-25; occurrenceID: 66033612-F89F-5029-A941-F6C49979C583; Taxon: scientificNameID: urn:lsid:marinespecies.org:taxname:716154; scientificName: Laevidentalium wiesei Sahlmann, 2012 ; kingdom: Animalia; phylum: Mollusca; class: Scaphopoda; order: Dentaliida ; family: Laevidentaliidae ; genus: Laevidentalium ; specificEpithet: wiesei ; taxonRank: species; scientificNameAuthorship: Sahlmann; nomenclaturalCode: ICZN; Location: higherGeography: Pacific Ocean; waterBody: Northeast Pacific Ocean, U. S. Exclusive Economic Zone, Alaska Region; locality: Aleutian Trench, AleutBio / SO 293 cruise, AleutBio station SO 293 _ 14-10 AGT ; verbatimDepth: 4877 m; minimumDepthInMeters: 4877; maximumDepthInMeters: 4877; verbatimCoordinates: 52°40.90'N, 161°51.71'W to 52°40.90'N, 161°51.72'W; verbatimCoordinateSystem: degrees decimal minutes; Identification: identifiedBy: Jan Steger; dateIdentified: 2024; identificationReferences: Sahlmann, B. (2012) Description of a new abyssal scaphopod, Laevidentalium wiesei , from the Kurile-Kamchatka Trench ( Mollusca, Scaphopoda). Schriften zur Malakozoologie aus dem Haus der Natur – Cismar, 27, 25–28.; Event: eventID: SO 293 _ 14-10 AGT; samplingProtocol: Agassiz trawl, contents sieved through a 1 mm mesh; samplingEffort: 1006 m trawled distance; eventDate: 2022-08 - 29 T 09: 57 Z / 2022 - 08 - 29 T 10: 30 Z; eventTime: 09: 57 Z / 10: 30 Z; year: 2022; month: 8; day: 29; habitat: abyssal sediment; fieldNumber: AB- 4794 | MOL- 1000; Record Level: language: en; institutionCode: SMF; basisOfRecord: PreservedSpecimen

Type status: Other material. Occurrence: catalogNumber: SMF 366427 ; recordNumber: AB- 4794; recordedBy: R / V SONNE AleutBio cruise SO 293; individualCount: 2; preparations: empty shell (fragments, in EtOH and air-dried); previousIdentifications: Dentaliida sp. M; associatedReferences: Brandt, A. (2022) (ed.) SO 293 AleutBio (Aleutian Trench Biodiversity Studies). SONNE-Berichte (R / V SONNE cruise reports). 209 pp.; occurrenceID: 37910B5D-DE34-51A0-90E4-BC1FB33E21D1; Taxon: scientificNameID: urn:lsid:marinespecies.org:taxname:716154; scientificName: Laevidentalium wiesei Sahlmann, 2012 ; kingdom: Animalia; phylum: Mollusca; class: Scaphopoda; order: Dentaliida ; family: Laevidentaliidae ; genus: Laevidentalium ; specificEpithet: wiesei ; taxonRank: species; scientificNameAuthorship: Sahlmann; nomenclaturalCode: ICZN; Location: higherGeography: Pacific Ocean; waterBody: Northeast Pacific Ocean, U. S. Exclusive Economic Zone, Alaska Region; locality: Aleutian Trench, AleutBio / SO 293 cruise, AleutBio station SO 293 _ 14-10 AGT ; verbatimDepth: 4877 m; minimumDepthInMeters: 4877; maximumDepthInMeters: 4877; verbatimCoordinates: 52°40.90'N, 161°51.71'W to 52°40.90'N, 161°51.72'W; verbatimCoordinateSystem: degrees decimal minutes; Identification: identifiedBy: Jan Steger; dateIdentified: 2024; identificationReferences: Sahlmann, B. (2012) Description of a new abyssal scaphopod, Laevidentalium wiesei , from the Kurile-Kamchatka Trench ( Mollusca, Scaphopoda). Schriften zur Malakozoologie aus dem Haus der Natur – Cismar, 27, 25–28.; Event: eventID: SO 293 _ 14-10 AGT; samplingProtocol: Agassiz trawl, contents sieved through a 1 mm mesh; samplingEffort: 1006 m trawled distance; eventDate: 2022-08 - 29 T 09: 57 Z / 2022 - 08 - 29 T 10: 30 Z; eventTime: 09: 57 Z / 10: 30 Z; year: 2022; month: 8; day: 29; habitat: abyssal sediment; fieldNumber: AB- 4794 | MOL- 1000; Record Level: language: en; institutionCode: SMF; basisOfRecord: PreservedSpecimen

Type status: Other material. Occurrence: catalogNumber: SMF 373200 ; recordNumber: AB- 4794; recordedBy: R / V SONNE AleutBio cruise SO 293; individualCount: 1; preparations: animal (partially dissected) and part of radula (EtOH) | metal-coated radula preparation on SEM stub (dry); previousIdentifications: Dentaliida sp. M; associatedReferences: Brandt, A. (2022) (ed.) SO 293 AleutBio (Aleutian Trench Biodiversity Studies). SONNE-Berichte (R / V SONNE cruise reports). 209 pp.; associatedSequences: https://portal.boldsystems.org/record/OSD003-25; occurrenceID: 968328A7-7937-5320-9CE6-4757C0D36D10; Taxon: scientificNameID: urn:lsid:marinespecies.org:taxname:716154; scientificName: Laevidentalium wiesei Sahlmann, 2012 ; kingdom: Animalia; phylum: Mollusca; class: Scaphopoda; order: Dentaliida ; family: Laevidentaliidae ; genus: Laevidentalium ; specificEpithet: wiesei ; taxonRank: species; scientificNameAuthorship: Sahlmann; nomenclaturalCode: ICZN; Location: higherGeography: Pacific Ocean; waterBody: Northeast Pacific Ocean, U. S. Exclusive Economic Zone, Alaska Region; locality: Aleutian Trench, AleutBio / SO 293 cruise, AleutBio station SO 293 _ 14-10 AGT ; verbatimDepth: 4877 m; minimumDepthInMeters: 4877; maximumDepthInMeters: 4877; verbatimCoordinates: 52°40.90'N, 161°51.71'W to 52°40.90'N, 161°51.72'W; verbatimCoordinateSystem: degrees decimal minutes; Identification: identifiedBy: Jan Steger; dateIdentified: 2024; identificationReferences: Sahlmann, B. (2012) Description of a new abyssal scaphopod, Laevidentalium wiesei , from the Kurile-Kamchatka Trench ( Mollusca, Scaphopoda). Schriften zur Malakozoologie aus dem Haus der Natur – Cismar, 27, 25–28.; Event: eventID: SO 293 _ 14-10 AGT; samplingProtocol: Agassiz trawl, contents sieved through a 1 mm mesh; samplingEffort: 1006 m trawled distance; eventDate: 2022-08 - 29 T 09: 57 Z / 2022 - 08 - 29 T 10: 30 Z; eventTime: 09: 57 Z / 10: 30 Z; year: 2022; month: 8; day: 29; habitat: abyssal sediment; fieldNumber: AB- 4794 | MOL- 1000; Record Level: language: en; institutionCode: SMF; basisOfRecord: PreservedSpecimen

Type status: Other material. Occurrence: catalogNumber: SMF 374281 ; recordNumber: AB- 4794; recordedBy: R / V SONNE AleutBio cruise SO 293; individualCount: 3; previousIdentifications: Dentaliida sp. M; associatedReferences: Brandt, A. (2022) (ed.) SO 293 AleutBio (Aleutian Trench Biodiversity Studies). SONNE-Berichte (R / V SONNE cruise reports). 209 pp.; occurrenceID: 654B832B-EE22-597E-9AD4-9F1876B7741B; Taxon: scientificNameID: urn:lsid:marinespecies.org:taxname:716154; scientificName: Laevidentalium wiesei Sahlmann, 2012 ; kingdom: Animalia; phylum: Mollusca; class: Scaphopoda; order: Dentaliida ; family: Laevidentaliidae ; genus: Laevidentalium ; specificEpithet: wiesei ; taxonRank: species; scientificNameAuthorship: Sahlmann; nomenclaturalCode: ICZN; Location: higherGeography: Pacific Ocean; waterBody: Northeast Pacific Ocean, U. S. Exclusive Economic Zone, Alaska Region; locality: Aleutian Trench, AleutBio / SO 293 cruise, AleutBio station SO 293 _ 14-10 AGT ; verbatimDepth: 4877 m; minimumDepthInMeters: 4877; maximumDepthInMeters: 4877; verbatimCoordinates: 52°40.90'N, 161°51.71'W to 52°40.90'N, 161°51.72'W; verbatimCoordinateSystem: degrees decimal minutes; Identification: identifiedBy: Jan Steger; dateIdentified: 2024; identificationReferences: Sahlmann, B. (2012) Description of a new abyssal scaphopod, Laevidentalium wiesei , from the Kurile-Kamchatka Trench ( Mollusca, Scaphopoda). Schriften zur Malakozoologie aus dem Haus der Natur – Cismar, 27, 25–28.; Event: eventID: SO 293 _ 14-10 AGT; samplingProtocol: Agassiz trawl, contents sieved through a 1 mm mesh; samplingEffort: 1006 m trawled distance; eventDate: 2022-08 - 29 T 09: 57 Z / 2022 - 08 - 29 T 10: 30 Z; eventTime: 09: 57 Z / 10: 30 Z; year: 2022; month: 8; day: 29; habitat: abyssal sediment; fieldNumber: AB- 4794 | MOL- 1000; Record Level: language: en; institutionCode: SMF; basisOfRecord: PreservedSpecimen

Description

Shell up to 45.6 mm long, maximum ventral aperture length 6.7 mm, ventral aperture width to 7.4 mm ( holotype, Fig. 15 A – D: 38.5 mm long, ventral aperture length 5.4 mm, ventral aperture width 5.9 mm), thin, but solid, tusk-shaped, gently recurved, with point of maximum curvature close to the mid-point of shell length in most of the specimens, located either dorsally or ventrally of it (Table 4 ). Outer surface glossy, ivory white to corneous in colour, ornamented with fine, densely arranged, irregular prosocline growth lines, without longitudinal (dorso-ventral) sculpture (Fig. 15 I, K, Fig. 16 L); growth interruptions are apparent at irregular intervals, but rather inconspicuous (Fig. 16 G) and partly obscured by corrosion; intermediate shell layer white where exposed. Aperture subcircular, slightly wider than long (Table 4 , Fig. 16 H – bottom virtual section), edge prosocline, sharp. Dorsal (apical) end of the shell eroded in all specimens known, with the exposed intermediate and / or inner shell layers taking various shapes, either truncate (e. g. HNC 43946 – Sahlmann (2012)), shallow ring-like (e. g. HNC 82015, Fig. 15 I – J) or more or less irregularly notched due to breakage along different sides (e. g. HNC 43947 – Fig. 15 C, SMF 366426 – Fig. 16 E – F); apical lumen circular in cross-section (Fig. 16 H – middle virtual section). Protoconch morphology unknown. Inner shell surface white, smooth and glossy. Anterior (concave) side of shell often hosts an unidentified (and potentially undescribed) species of large-sized (up to 23 mm in preserved specimens) epibiotic sea anemone (Table 4 , Fig. 15 A – B, Fig. 15 D, Fig. 16 A, Fig. 16 H – K); CT scans revealed no evidence of the anemone corroding or penetrating the scaphopod shell (Fig. 17 A).

Gross anatomy (Fig. 17 ) follows typical dentaliid body plan (Fig. 17 A); preserved body length of SMF 366426 ( 23.5 mm) around half the shell length ( 45.6 mm), gonad visible in CT scan is likely male. Captacular mass large and very dense. Dorsal pavilion relatively long ( 3 mm), robust.

Radula well-developed, with five teeth per row (formula 1-1 - 1 - 1 - 1; Fig. 17 D); mature teeth brown in colour / mineralised, consistent with a foraminifera-dominated diet (Fig. 17 B – C). Central teeth crescent-shaped, with convex superior face (eroding to concave in worn teeth) and adjacent granulose face (Fig. 17 F – G); lateral teeth dumb-bell-shaped without cusps on working surface (Fig. 17 D – E), marginals rather stout for the genus (cf. Glover et al. (2003) Lamprell and Healy (1998), Glover et al. (2003)), upright rectangular with rounded corners, basal part almost straight-sided, bent on quarter closest to lateral teeth (Fig. 17 E).

Type material

Holotype ( HNC 43947) and three paratypes ( HNC 43946, HNC 82014, HNC 82015). Only dry-preserved shells were available for the original description, although their overall condition and glossy inner surface suggests they originated from live-collected specimens.

Material examined

Holotype HNC 43947 and paratype HNC 82015 (specimens examined and measured), plus new material from the Aleutian Trench (lots SMF 366425, 366426, 366427, 373200, 374281 – all collected together at a single station, see Materials for details).

Type locality

Kurile-Kamchakta [ sic] Trench, 45°N, 156°E ( Sahlmann 2012), collected at water depths ranging from 4500 m to 5210 m.

Diagnosis

Adult shell length to> 45 mm, ratio of shell length to ventral aperture length 7–9, gently recurved, without longitudinal keels, surface glossy, but often heavily corroded, smooth, except for dense prosocoline incremental lines; colour ivory white to corneous; ventral aperture subcircular, slightly wider than long, prosocline and sharp-edged. Anterior shell face usually hosting a single epibiotic sea anemone. Radula with crescent-shaped central teeth with granulose anterior face, lateral teeth without cusps, marginals rather stout for the genus, rectangular with rounded corners, basal part almost straight-sided, bent on quarter closest to lateral teeth.

Distribution

Known from the abyssal plain east of the Kuril Kamchatka Trench (type locality; Sahlmann (2012)) and the southern edge of the eastern Aleutian Trench ( Sigwart et al. 2025, this study) at depths of 4500–5210 m. Sahlmann (2012) suspected that the records of “ Laevidentalium sp. ” reported by Okutani (1975), p. 76, from R / V SOYO-MARU Station 150 (Philippine Sea southeast of Kyushu, Japan, 29°52.4’N, 133°06.2’E, 3610 m water depth) and R / V KAIYO-MARU Station D (abyssal plain east of northern Honshu, Japan, 36°03.2’N, 157°51.4’E, 4370 m water depth) might correspond to this species; alternatively, these records may concern a closely-related species or species complex (see remarks in Okutani (1975)).

Taxon discussion

Two other Laevidentalium species have been recorded from abyssal depths in the Pacific Ocean – L. largicrescens (Tate, 1899) and L. leptosceles (R. B. Watson, 1879) . Both can be distinguished from L. wiesei by shell and radula characters; furthermore, no Laevidentalium species other than L. wiesei is known to host an epibiotic sea anemone. Laevidentalium largicrescens is conchologically most similar, but differs from L. wiesei by the circular ventral aperture, the occasional presence of a posterior apical notch, cusps on the working surface of the lateral radular teeth and sigmoidal, much more elongated marginal teeth. It has a very different geographical range, occurring in the Southern Hemisphere, off the eastern Australian coast at 284–3058 m depth ( Lamprell and Healy 1998). Laevidentalium leptosceles (R. B. Watson, 1879) is more slender, bears a weak, flexuous longitudinal sculpture in the apical part of the shell – lacking in the synonymised, shallower-water taxon L. banale (Boissevain, 1906) – and has a subcircular apical cross-section ( Watson 1879, Lamprell and Healy 1998); it is widely distributed in the Indian Ocean and Western Pacific, with live records ranging from 2200–5300 m depth ( Scarabino 1995).

The Atlantic abyssal L. abyplainae Scarabino & Scarabino, 2011 , differs – besides its biogeography – by a straighter shell that expands less in diameter towards the ventral aperture, as well as by the presence of fine longitudinal striations on its apical part ( Scarabino and Scarabino 2011, Sahlmann 2012). It shares with L. wiesei the granulose anterior face of the central radular teeth, but the lateral teeth are shaped differently and bear cusps ( Scarabino and Scarabino 2011); the marginal teeth are relatively shorter than in L. wiesei .

The only large-sized scaphopod within the North Pacific recorded at abyssal depths and superficially resembling L. wiesei is Rhabdus toyamaensis ( Kuroda & Kikuchi, 1933) . Although it usually inhabits much shallower depths ( Kuroda and Kikuchi 1933, Habe 1964, Habe 1977, Okutani 2000), a single specimen was collected at 5100 m in the Aleutian Trench, south of Attu Island ( 52°12’N, 175°44’E) ( Sahlmann (2015), as Rhadbus toyamaense ( Kuroda & Kikuchi, 1933)) . Rhabdus toyamaensis attains much larger sizes than L. wiesei (up to 10 cm long), is more slender (the ventral aperture diameter of the Aleutian Trench specimen is just 4 mm at 61.5 mm shell length), has a completely circular ventral aperture and a shell sometimes bearing alternating light and dark bands. The abyssal specimen reported by Sahlmann (2015) – besides its unusual bathymetric and geographic location – also shows morphological differences from typical R. toyamaensis , such as subtle, but clearly visible annular swellings along the shell in addition to regular growth increments and an extremely glossy surface, suggesting it might actually be an undescribed species.

The most obvious feature of L. wiesei is the epizoic anemones attached to the anterior shell face of live individuals, an association previously reported only from members of the genus Fissidentalium ( Dall 1908, Shimek and Moreno 1996, Shimek 1997, Linse and Neuhaus 2024). The shells of these species – F. actiniophorum Shimek, 1997 , F. aurae Linse & Neuhaus, 2024 , F. megathyris (Dall, 1890) and F. peruvianum ( Dall, 1908) – however, all have distinct longitudinal ribs, which differentiate them at first sight from the smooth-shelled L. wiesei .

Notes

Laevidentalium wiesei Sahlmann, 2012 was originally described, based on four empty shells collected at abyssal depths in the Kuril Kamchatka Trench region, north-west Pacific Ocean. The type material, entirely housed in the malacological collection of Haus der Natur – Cismar ( Germany), was obtained by the Museum in 1995 from private shell collections, accompanied by only basic locality data. Following its description ( Sahlmann 2012), no further records of this poorly-known species were published until several, mostly live-collected, specimens were sampled in 2022 by the AleutBio expedition to the Aleutian Trench and adjacent abyssal parts of the Bering Sea, north-east Pacific Ocean ( Brandt 2022, Sigwart et al. 2025). This new material enabled a more detailed, integrative re-description and constitutes a significant geographic range extension.

Methods

Specimens of L. wiesei from the SO 293 AleutBio expedition were collected using a 3.5 m-wide Agassiz trawl with 10 mm cod end mesh size (OKTOPUS GmbH). Contents of the net were sieved on a 1 mm mesh and subsequently preserved in 96 % ethanol (lots SMF 366425, SMF 366426, SMF 366427 and SMF 373200) or 4 % buffered formalin-seawater ( SMF 374281; Brandt (2022)).

Photographs of entire scaphopods were taken with a CANON EOS 6 D camera, equipped with an EF 100 mm 1: 2.8 IS USM macro lens and serial images stacked with Helicon Focus software (v. 5.3 X 64; HELICON SOFT). Details of the outer shell surface were photographed using: (i) a motorised NIKON SMZ 25 stereomicroscope with an attached NIKON Digital Sight 10 camera and (ii) a HITACHI TM 4000 Plus Tabletop scanning electron microscope (SEM) without metal coating. Stereo-microscopic images were stacked with NIKON NIS Elements Basic Research ( BR) software (v. 5.42. 04).

After initial photographic documentation, shell shape and soft body anatomy were studied by micro-computed tomography (micro-CT), using a WERTH TomoScope XS Plus CT scanner with the following settings [scan of SMF 373200 / scan of SMF 366426]: acceleration voltage 60 / 80 kV, emission current 180 / 200 µA, exposure time 666 ms, voxel size 6.29 / 21.81 µm, number of images per revolution 2000 / 1000. Prior to CT scanning, specimens had been contrasted in a solution of 0.3 % phosphotungstic acid and 3 % dimethyl sulphoxide in 95 % ethanol ( Senckenberg Ocean Species Alliance (SOSA) et al. 2024) for 27 days. X-ray virtual sections were produced in Dragonfly software (v. 2022.2; OBJECT RESEARCH SYSTEMS). The 3 D shell reconstruction of SMF 366426 and virtual shell sections were obtained by first cropping the raw tomographic dataset in Avizo 3 D (v. 2024.1; THERMO FISHER SCIENTIFIC) and postprocessing the resultant file in VGSTUDIO MAX (v. 2024.3; VOLUME GRAPHICS). The tomographic datasets and the surface model of SMF 366426 are available from Zenodo (https://doi.org/10.5281/zenodo.15470822).

Shell morphometric measurements follow Shimek and Moreno (1996) and were taken from macrophotographic images using NIS Elements BR software.

For radula preparation, the entire buccal mass of specimen SMF 373200 was dissected and the soft tissue dissolved in diluted commercial bleach (a 5 % sodium hypochlorite solution). Following a ca. 10 s cleaning step in an ultrasonic bath (cf. Shimek and Moreno (1996)), the radula was dehydrated in absolute ethanol, transferred to hexamethyldisilazane ( HMDS) through an ascending series of ethanol-HMDS mixtures and finally left to air-dry at room temperature in a fume hood overnight. The preparation was subsequently mounted on an aluminium stub with a double-sided adhesive tab, sputter-coated with gold-palladium and imaged using a HITACHI TM 4000 Plus Tabletop SEM.

Figure plates for this contribution were assembled with Adobe Photoshop 2025.

COI sequences of L. wiesei were obtained by the procedures detailed in Linse and Neuhaus (2024).

Specimen data for this description were gathered and processed via the Discovery Laboratory of the SENCKENBERG OCEAN SPECIES ALLIANCE.

Repository: Type material is held at Haus der Natur – Cismar ( HNC), Cismar, Germany and additional specimens at the Senckenberg Research Institute and Natural History Museum Frankfurt ( SMF).

Figures

Figure 15. Laevidentalium wiesei Sahlmann, 2012, type material. A – D Holotype HNC 43947, anterior (A), right side (B), posterior (C) and left side (D) views. Note the dry remains of the epizoic anemone attached to the anterior face of the shell; E – K Paratype HNC 82015, anterior (E), right side (F), posterior (G) and left side (H) views; dorsal aperture in lateral (I; scanning electron micrograph) and apical (J) view; scanning electron micrograph showing the microsculpture consisting exclusively of densely arranged incremental lines (K). Scale bars: 10 mm (A – H), 1 mm (I, K), 0.5 mm (J).

Figure 16. Laevidentalium wiesei Sahlmann, 2012, specimens from the AleutBio expedition. A – H Specimen SMF 366426, anterior (A), right side (B), posterior (C) and left side (D) views; close-ups of dorsal part of shell in posterior (E) and right side (F) view; detail of postero-ventral shell portion with growth mark indicated by arrowhead (G); micro-CT-based 3 D reconstruction (left side view) and virtual cuts through the shell (perpendicular to the central axis) (H). Note the subcircular – wider than long – lumen of the ventral part of the shell that becomes circular dorsally; I – K Specimen SMF 373200 (shell broken during sampling event), right side (I) and posterior (J) views; close-up of the epizoic anemone attached to the anterior face of the shell (K); L Shell fragment from lot SMF 366427, scanning electron micrograph showing microsculpture. Scale bars: 10 mm (A – D, H – shell reconstruction, I – J), 5 mm (E – F, K), 2.5 mm (G), 2 mm (H – virtual shell sections), 1 mm (L).

Figure 17. Laevidentalium wiesei Sahlmann, 2012, anatomy and radula. A Specimen SMF 366426, virtual cross section from x-ray tomography with major internal structures indicated. Abbreviations: DV muscle, dorso-ventral muscle; B – G Specimen SMF 373200, virtual cross sections from x-ray tomography showing tests of ingested foraminifera (B – C; scaphopod soft body not shown for clarity), overview of radula (D; Abbreviations: cen, central tooth; lat, lateral tooth; mar, marginal tooth), close-up of lateral and marginal teeth (E), of central tooth (F) and detail of granulose face of the latter (G). Scale bars: 10 mm (A), 1 mm (B – C), 0.5 mm (D – E), 0.1 mm (F), 0.03 mm (G).