Buccinum hasegawai, Kantor & Sirenko & Zvonareva & Fedosov, 2022

Kantor, Yuri, Sirenko, Boris, Zvonareva, Sofya S. & Fedosov, Alexander, 2022, Taxonomic status of genera of Buccininae (Neogastropoda, Buccinidae) updated based on molecular data with description of new species and corrections of nomenclature of Buccinum, European Journal of Taxonomy 817, pp. 11-34 : 21-24

Buccinum hasegawai sp. nov.

urn:lsid:zoobank.org:act:2CEE5E56-6C96-445E-91ED-D5E8E30B928F

Figs 4 , 6A–C ; Table 1

Buccinum (Buccinum) bombycinum – Golikov 1980: 327, figs 85, 183, 391, 1 pl. XXXI, 1a–1k (part.) (non Dall 1907).

Bathybuccinum (Ovulatibuccinum) bombycinum – Golikov & Sirenko 1988: 87 (non Dall 1907).

Bathybuccinum bombycinum – Golikov & Sirenko 1998: 122, fig. 12b; Kantor & Sysoev 2006:160, pl. 74c (non Dall, 1907).

? Buccinum sp. cf. bulimuloideum – Okutani 1964: 414, pl. II fig.12 (non Dall 1907).

Bathybuccinum sp.1 — Sirenko et al. 2013:159.

Diagnosis

Shell reaching 18.5 mm in length, thin, oval to elongate-oval, smooth. Axial sculpture only of thin growth lines, spiral sculpture absent. Operculum thin, small, less than ¼ of AL, with nucleus notably shifted towards lower outer edge.

Etymology

Named in honour of Dr Kazunori Hasegawa, Japanese malacologist whose studies made a significant contribution to the systematics of the deep-sea gastropods of Japan and the Pacific.

Type material

Holotype KURILE ISLANDS • lv; South-east of Simushir I.; 46°40.6′ N, 151°58.4′ E; depth 436 m; R/V Akademik Oparin, cruise 56, stn 19; ZIN 62775, Buc274 .

Paratypes KURILE ISLANDS • 1 lv (paratype 1, SL 14.8 mm); same collection data as for holotype; ZIN 62902 , Buc276 • 1 lv (paratype 2, SL 14.7 mm); Okhotsk Sea , Urup I. ; 46°15.9′ N, 150°15.4′ E; depth 450–460 m; R/V Oparin, cruise 56, stn 24; MIMB 42300 , Buc273 • 8 lv (SL 9.0– 16.2 mm); Iturup I. ; 44°20.8′ N, 148°24.0′ E; depth 414 m; Kurile-Sakhalin Expedition, F/T Toporok, stn 101; 14 Sep 1949; ZIN 26228 • 7 lv; Iturup I. ; 44°52′ N, 149°27.7′ E; depth 910–920 m; R/V Odyssey; 25 Jul. 1984; ZIN 48100 .

Other material examined

Sequenced material

Holotype, paratypes 1, 2 (see above on localities).

Not-sequenced material

KURILE ISLANDS • 1 lv (SL 16.5 mm); Shikotan I. ; 43°37′ N, 147°19′ E; depth 400 m; R/V Tikhookeanskyi; 11 Jul. 1987; ZIN 62780 • 1 lv (SL 16.0 mm); Iturup I. ; 44°05.7′ N, 148°05.4′ E; depth 500 m; R/V Tikhookeanskiy; 10 Aug. 1987; ZIN 62779 .

SEA OF OKHOTSK • 3 lv (SL 15.0–16.0 mm); Southern Sakhalin, 47°50.4′ N, 142°53.5′ E; depth 78 m; Kurile-Sakhalin Expedition; F/T Toporok; stn 145; 30 Sep.–1 Oct. 1949; ZIN 26226 .

Description

MEASUREMENTS (holotype, largest specimen). SL 18.5 mm, AL 9.2 mm, SW 8.6 mm.

SHELL. Thin, fragile, oval to elongate-oval, smooth, with short siphonal canal, chocolate-brown in fresh specimens to brownish and olive with lighter convex strongly demarcated fasciole. Protoconch eroded in available material, rendering exact whorl count impossible. Teleoconch whorls up to 4+. Suture distinct, adpressed at periphery of previous whorl. SW/SL ratio 0.48 (holotype) to 0.58, LW/SL ratio 0.75 (holotype) to 0.84. Axial sculpture of thin prosocline growth lines, spiral sculpture absent. Aperture large, semi-oval. Outer lip thin, slightly pressed adapically. Columella smooth, nearly straight, sometimes weakly concave, lighter than shell. AL/SL ratio 0.51 (holotype) to 0.63. Siphonal notch wide and rather shallow. Periostracum very thin, smooth, tightly adhering. Operculum ( Fig. 6B ) small, thin, yellowish, transparent, oval, with nucleus strongly displaced to lower edge, spanning about 0.25 of AL.

RADULA (n = 1). Rachidian tooth with rectangular basal plate and three equal, short cusps. Lateral tooth with three cusps, outer cusp longest, intermediate shortest and most narrow ( Fig. 6A ).

PENIS (n = 1). Distal part with large hook-shaped papilla, surrounded by circular fold ( Fig. 6C ).

HEAD- FOOT. Characteristically strongly pigmented on the dorsal side, nearly black in fresh specimens, fading with time in alcohol.

Remarks

The species is variable in shell shape and coloration ( Fig. 4 ). The shell can range from oval, with a protruded basal edge of the outer apertural lip ( Fig. 4E, G ) to narrowly oval with non-protruded lip ( Fig. 4A–D ). Shell color varies from brown to olive, although it is possible that the color fades over time in alcohol, since lightest shells were collected in 1949, while most dark specimens were collected in 2019.

The size of the operculum varies significantly, constituting from 1 / 6 to ¼ of AL.

Golikov (1980) identified this species (together with B. bizikovi sp. nov.) as Buccinum bombycinum based on Dall’s (1907) incorrect report of the type locality for this species (east coast of Sakhalin, in 53 m). However, it turned out that the type locality was Suruga Bay, Japan in 527 m ( Kuroda 1950; Hasegawa & Okutani 2011). Later, when examining the samples in which both new species were sympatric, Golikov & Sirenko (1998) recognized the presence of two species and identified the specimens with a narrow shell as Bathybuccinum bombycinum , and those with a wider shell ( B. bizikovi sp. nov.) as B. ovulum . Kantor & Sysoev (2006: 160) pointed out that the specimens identified as B. bombycinum by Golikov and Golikov & Sirenko belong to a different, possibly undescribed species.

The new species is clearly different from Buccinum bombycinum ( Fig. 4H–I ) in having a much narrower, smooth shell with a smaller operculum. Furthermore, in B. bombycinum the upper whorls bear distinct spiral cords ( Fig. 4I ). Hasegawa & Okutani (2011: fig. 26) illustrated a specimen of B. bombycinum from Sagami Bay with even better developed spiral sculpture, covering the entire shell surface. B. bombycinum is probably endemic of Honshu. For the comparison with B. bizikovi sp. nov. see under remarks of the latter species.

In the molecular phylogeny, the new species is clustering with maximal support with two morphologically very different species, Buccinum sp. 1 and Buccinum sp. 2 . From the former ( Fig. 2I ) it differs in much narrower shell and absence of the distinct spiral keel on the shoulder. From the latter ( Fig. 2C ) the new species differs in much narrower shell, higher spire, lack of spiral cords, and smooth and thin periostracum vs thick and leathery one.

Distribution

Kurile Is (Iturup I., Shikotan I., Simushir I.), Sea of Okhotsk, South Sakhalin, depth 78– 910 m.

Figures

Fig. 4. Buccinum hasegawai sp. nov. A–B. Holotype (ZIN 62775 (Buc274)), SL 18.5 mm. C. Paratype 1 (ZIN 62902 (Buc276)) from the type locality, SL 14.8 mm. D. Paratype 2 (MIMB 42300 (Buc273)), Urup I., 450–460 m, SL 14.7 mm. E. Paratype (ZIN 26228), Iturup I., 414 m, SL 16.1 mm. F. Paratype (ZIN 26228), Iturup I., 414 m, SL 16.2 mm, lateral view to show the penis. G. Buccinum bombycinum Dall, 1907 (ZIN 48100) Iturup I., 910–920 m, SL 15.3 mm. H–I. Syntype (USNM 1105311), Japan, Honshu I., Suruga Bay, 536 m, SL 23.9 mm. I = enlarged upper part of the shell to show the sculpture. Scale bars: A–H = same scale; I = 5 mm. Photos H–I: courtesy of USNM.

Fig. 6. Buccinum hasegawai sp. nov. (A–C) and Buccinum bizikovi sp. nov. (D–F). A–B. Paratype (ZIN 62777), SL 16.5 mm. A. Radula. B. Operculum. C. Paratype (ZIN 62782), penis. D. Paratype (ZIN 62782), SL 16.5 mm, radula. E. Paratype (ZIN 62782), SL 19.1 mm, operculum. F. Paratype (ZIN 62782), SL 16.5 mm, penis. Scale bars: C, F = 1 mm.

Fig. 2. Sequenced species of Buccinum Linnaeus, 1758 previously attributed to Thysanobuccinum Golikov & Gulbin in Golikov, 1980, Bathybuccinum Golikov & Sirenko, 1988 and Ovulatibuccinum Golikov & Sirenko, 1988. A–B. Buccinum tunicatum Golikov & Gulbin, 1977 (Buc265), Okhotsk Sea, off Urup I., depth 142 m, R/V Akademik Oparin, 56 cr., sta 7, SL 20.4 mm. C. Buccinum sp. 2 (Buc175), off Onagawa, Miyagi, Honshu I., Japan, depth 3302–3311 m, SL 20.3 mm. D–D’. Buccinum cf. tunicatum (Buc269), Okhotsk Sea coast of Urup I., 2 m, R/V Akademik Oparin, 56 cr., sta 26, SL 8.7 mm. D = at the same scale as others; D’= enlarged.E–E’. Buccinum bicordatum (Golikov & Sirenko, 1988) (Buc188), off Onagawa, Miyagi, Honshu I., Japan, depth 342–343 m, SL 8.4 mm. E = at the same scale as others; E’ = enlarged. F. Buccinum unicordatum (Golikov & Sirenko, 1988) (Buc266), Kurile Is, Iturup I., Prostor Bay, depth 264–270 m, SL 15.9 mm. G. Buccinum chinoi nom. nov. (Buc190), off Onagawa, Miyagi, Honshu I., Japan, depth 342–343 m, SL 9.0 mm.H. Buccinum fimbriatum (Golikov & Sirenko, 1988) (Buc275), Kurile Is, Simushir I., depth 436 m, R/V Akademik Oparin, 56 cr., stn 19, SL 16.6 mm. I. Buccinum sp. 1 (Buc189), off Onagawa, Miyagi, Honshu I., Japan, depth 342–343 m, SL 22.4 mm. All shells (except D’, E’) at the same scale.