Boreotrophon oparini, Bondarev, 2022

Bondarev, I. P., 2022, A new species of Boreotrophon P. Fischer, 1884 (Gastropoda, Muricidae, Pagodulinae) from the Sea of Japan, Ruthenica, Russian Malacological Journal 32 (2), pp. 81-84 : 82-84

Boreotrophon oparini sp. nov.

( Figs 2 A–J , Table 1)

Zoobank registration: urn:lsid:zoobank.org:act:F8174FD1-64F6-4377-A297-68B48663273A

Type material: holotype ZMMU Lc-41237 , SH 46.2 mm, w/o ( Figs 2 A–E ); paratype IBSS, #ibss. bent.1.Mol. p., SH 41.1 mm, w/o ( Figs 2 F–J ).

Type locality: Sea of Japan, off Russian Maritime Territory: 44°04.0’N, 135°40.0’E, 40 m depth, bivalves shells, sand, gravel and pebbles bottom (holotype); 43°40.5’N, 135°26.3’E, 110 m depth, gravel and pebbles bottom (paratype) .

Etymology: The species is named in honor of academician A.I. Oparin.

Diagnosis. Boreotrophon oparini sp. nov. is characterized by a medium sized fusiform shell ( SH / SW ratio – 2.35) consisting of 6 slightly angulated whorls with barely visible spiral lines and cords and 9 or 10 widely spaced axial lamellae; spire moderately high, siphonal canal moderately long (1/3 of the shell height) broadly open. Color whitish to light cream or brown with occasionally spread light brown spots, mostly on lighter colored axiallamellae and outer lip. Operculum elongated oval, dirty–yellow.

Description. Shell fusiform consisting of 6 slightly angulated whorls, moderately solid, medium sized for the genus, up to 46.2 mm in height (holotype), SH / SW ratio – 2.35, suture impressed. Protoconch is unknown. Spire moderately high, spiral sculpture consisting of barely visible lines and cords (more visible on paratype), axial sculpture consisting of very thin growth lines and rather low, widely spaced lamellae 9 (paratype) or 10 (holotype) on the last teleoconch whorl. Aperture ovate, distinctly separated from broadly opened, slightly curved backward moderately long siphonal canal covering 1/3 of the total shell height, tips of previous canals projected behind. Aperture is milky white to light cream with yellowish tint and light brown small spot on the outer lip. Outer lip is smooth within, inner lip covered by thin glossy callus. Shell whitish or cream to brown on the spire whorls, which are obviously worn and the whitish outer shell layer is eroded (less in the paratype), so the shell naturally would be more whitish. Tip of holotype siphonal canal is brown, siphonal canal of paratype white to light cream.Axiallamellae white to light cream, with occasionally spread light brown spots. Operculum is small, elongated oval, OH / OW ratio – 1.85–1.89, dirty–yellow.

Distribution. Known only from the type locality.

Remarks. Boreotrophon oparini sp. nov. differs from the sympatric B. candelabrum by its more slender shell with less developed axial lamellae and longer siphonal canal. B. candelabrum ( Fig. 3 A–H ) has a darker and bright shell color with light pinkish-brown to brown-violet aperture, occasionally with brown bands or spots; the operculum is dark brown. B. candelabrum is a mostly shallow water sublittoral species, but can be found up to 90-100 m depth [ Golikov, Kussakin, 1978]. The shell of the other sympatric species B. alborostratus ( Fig. 3 I–J ) is similar in its general shape, but wider ( SH / SW ratio – 2.05) with more rounded aperture; the axial lamellae are more numerous (12–14), the siphonal canal is slightly turned left vs. backside in the new species, the shell is white vs. light cream to brown in B. oparini sp. nov. B. alaskanus Dall, 1902 differs by its white or greyish white color, stronger and fewer (7–8) axial lamellae projecting at shoulder, occasionally upturned. B. cepula (Sowerby, 1880) differs by its more uniformly paler colored shell, a smaller average size (21 mm), more rounded whorls and aperture, respectively shorter canal and more numerous axial lamellae (15–17) on the body whorl. The new species differs from the Boreal–Arctic B. clathratus by fewer axial lamellae (9–10 vs. 10–12 to 16–17), more slender general shell shape, and an oval elongate vs. almost round aperture. B. clathratus is quite variable because of the wide almost circumpolar distribution and depth interval from 0.5 m to more than 1200 m. Specimens fromnorthwest Pacific named Boreotrophon beringi Dall, 1902 , [ Egorov, 1993, fig. 31 G, H; Kantor, Sysoev, 2006, pl. 63K] with a rather long siphonal canal differs from the new species by its canal turned left and by the absence of spotted color pattern and an aperture sometimes yellowish-brown to dark-brown colored. B. egorovi Houart, 1995 differs by its greenish–white shell,

Табл. 1 Основные морфологические характеристики Boreotrophon oparini sp. nov. (раЗмеры в мм).

РИС. 3. Boreotrophon candelabrum (A–H) Приморье, глубина 8-12 м (A–F): A, B – 43,2 мм, C, D – 39,9 мм, E–F – 24,0 мм; Курильские о-ва, глубина 60 м (G–H) – 33,7 мм; B. alborostratus (I–J) Приморье, глубина 140 м – 40,0 мм.

broad rounded teleoconch whorls and by its white or brown aperture with white rim, the operculum is dark brown. B. okhotensis Egorov, 1993 differs by its very thick, broad and solid shell consisting of 4.5 greyish white whorls, with a shorter siphonal canal (1/4 of the total shell height) strongly curved to the left, more numerous axial lamellae (13 on the body whorl) and an operculum with dark brown spot in the center.

Figures

FIG. 2. Boreotrophon oparini sp. nov. A–E. Holotype ZMMU Lc-41237, 46.2 mm: ventral (A) dorsal (C), right (D) and left (E) views, B – aperture with operculum 9.1 mm x 4.8 mm. F–J. Paratype IBSS, 41.1 mm ventral (F) dorsal (H), right (I) and left (J) view, G – aperture with operculum 8.5 mm x 4.6 mm.

FIG. 3. Boreotrophon candelabrum (A–H) Primorye, depth 8–12 m (A–F): A, B – 43.2 mm, C, D – 39.9 mm, E–F – 24.0 mm; Kuril Is., depth 60 m (G–H) – 33.7 mm; B. alborostratus (I–J) Primorye, depth 140 m – 40.0 mm.