Menestho schikovi Nekhaev 2017
- Dataset
- A new species of Menestho Møller, 1842 from the Arctic with remarks on Menestho albula (Fabricius, 1780) (Gastropoda: Heterobranchia: Pyramidellidae)
- Rank
- SPECIES
- Published in
- Nekhaev, Ivan O. (2017): A new species of Menestho Møller, 1842 from the Arctic with remarks on Menestho albula (Fabricius, 1780) (Gastropoda: Heterobranchia: Pyramidellidae). Zootaxa 4347 (1), DOI: 10.11646/zootaxa.4347.1.13
Classification
- kingdom
- Animalia
- phylum
- Mollusca
- class
- Gastropoda
- order
- Heterostropha
- family
- Pyramidellidae
- genus
- Menestho
- species
- Menestho schikovi
description
Derivation of name. The species is named after Dr. Evgenij Schikov, enthusiastic malacologist and ecologist.
description
Description: Shell small, conical, white or yellowish with convex, evenly rounded whorls divided by deep suture (Figs. 1 A, C, E, 2 A). Shell surface with fine, frequent (8 – 11 on body whorl), spiral ribs, almost semicircular in section, divided by very narrow interspaces (Fig. 2 I). Axial sculpture, except for straight growth-lines (Fig. 2 A, I) absent. Embryonic shell intorted, of type B, partially eroded on studied specimens, smooth or with very low pattern of spiral sculpture (Fig. 2 G). Aperture oval with acute angle in upper part, no teeth or folds on columella. Umbilicus clearly visible, narrow. Operculum transparent, without peg (Fig. 2 E). Measurements of holotype: shell height = 3.6 mm, aperture height = 1.2 mm, last whorl height = 2.3 mm, shell width = 2.0 mm, aperture width = 1.0 mm. Variability. Studied shells differ in width / height proportions (Fig 1 A, C, E), no other significant variability had been found.
diagnosis
Diagnosis: Menestho with conical shell, convex, evenly rounded whorls, open umbilicus and straight growth-lines.
discussion
Remarks. Shell of Menestho truncatula (Figs. 1 D, 2 B) (see also Odhner (1915) for the figures of syntypes) is wider than M. schikovi, upper part of its last whorl with flattened shoulder, not rounded. The aperture height in M. truncatula is about a half of shell height. In addition, M. truncatula have a reticulate pattern on the protoconch (Fig. 2 F). Menestho albula differs from M. schikovi by prosocline growth-lines and absence of an umbilicus. Usually Menestho albula have coarser spiral sculpture and more flattened whorls.
distribution
Distribution. Known from the Svalbard, the Kara and the Laptev seas. Single young specimen (ZIN 60879) with shell height = 2.5 mm corresponded to Menestho schikovi was found from the Chukchi Sea. Depth range 42 – 585 m. Probably, the species lives in all seas of the Eurasian Arctic. Habitat. The species had been collected from silt substrates. The observed near-bottom temperature and salinity at the type locality were - 1.4 ° C and 34.8 psu respectively. Menestho schikovi probably have a parasitic mode of life, like other pyramidellid species. However its host is unknown.
materials_examined
Type material. holotype (empty shell) (Figs 1 A, 2 A, I), 3.12.2015, van Veen grab, ZIN 62135 / 1, 6 paratypes (empty shells) from the same sample ZIN 62136 / 2 and 2 paratypes (empty shells) from the same sample LMBI IN- 3. Type locality. Svalbard, Spitsbergen Island, Billefjorden, R / V Dalnie Zelentsy, sta. 44, 78 ° 39.6 ' N, 16 ° 40.4 ' E, 188 m. Other examined material: 3 spms, 2 shells, Kara Sea, 76 ° 41 ' N, 88 ° 14 ' E, 45 m, R / V G. Sedov, leg. Vagin, 0 6.09.1934, ZIN 22732 (studied with SEM); 4 spms, Kara Sea, 75 ° 40 ' N, 80 ° 26 ' E, 42 m, R / V G. Sedov, leg. Vagin, 0 9.09.1934, ZIN 35691; 3 spms, Kara Sea, 76 ° 17 ' N, 75 ° 08 ' E, 75 m, R / V G. Sedov, leg. Vagin, 21.09.1934, ZIN 35693; 1 spm, Severnaya Zemlya, 80 ° 30 ' N, 90 ° 03 ’ E, 174 m, R / V Fyodor Litke, 29.09.1948, ZIN 35701; 1 spm, Laptev Sea, 77 ° 25 ' N, 115 ° 48 ' E, 62 m, R / V Sadko, leg. G. P. Gorbunov, 16.08.1937, ZIN 35696; 2 spms, Laptev Sea, 76 ° 36 ' N, 118 ° 30 ' E, 51 m, R / V Sadko, leg. G. P. Gorbunov, 0 2.10.1937, ZIN 35697; 1 spm, 71 ° 24 ' 78 '' N, 174 ° 22 ' 03 '' E, 585 m, R / V Professor Chromov, 22.08.2004, ZIN 60879.
Name
- Homonyms
- Menestho schikovi Nekhaev 2017