Cylichnoides scalptus (Reeve, 1855)

Chaban, E. M., 2016, Opisthobranch molluscs of « Cylichna occulta group » (Gastropoda: Opisthobranchia: Cylichnidae) from the Chukchi Sea and adjacent waters, The Bulletin of the Russian Far East Malacological Society 20, pp. 5-26 : 18-21

Cylichnoides scalptus (Reeve, 1855)

Figs 3A ; 6A–H ; 7A–J

Bulla scalpta Reeve, 1855, p. 392 –393, pl. 32, figs 3a, b, c.

Cylichna scalpta (Reeve, 1855) : Leche, 1878, p. 73, tab. 1, fig. 22.

Cylichna (Bullinella) scalpta (Reeve, 1855) : Filatova, Zatsepin, 1948, p. 394, pl. 53, fig. 8.

Cylichna occulta ( Mighels et Adams, 1842) : Pilsbry, 1893, p. 292 (part.), fig. 35; Lemche, 1956, p. 225, pl. 1, fig. 3, 4 (non Mighels et Adams).

Cylichnoides scalpta (Reeve, 1855) : Chaban, 2001, p. 108; Chaban, 2004, p. 82 –83, fig. 5E, F; Chaban, 2010, p. 75 –76, fig. 6.4; Chaban, Martynov, 2006, p. 254, pl. 126, fig. F; Nekhaev, 2014, p. 110, fig. 15D.

Type locality. Spitsbergen.

Type s p e c i m e n s. Lost [ Lemche, 1948].

Material studied. Barents Sea: R / V «Persey»: station 862, 22.IX.1927, 73º59′ N, 63º25′ E, depth 79 m – 2 specimens ; station 866, 22.IX.1927, 75º21′ N, 65º10′ E, depth 340 m – 1 specimen; Kara Sea: icebreaker «Rusanov», 1932, station 20, 70º47′ N, 63º59′ E, depth 130 m, mud – 7 specimens; icebreaker «Sedov», 1934, station 51, 77º28′ N, 86º32′ E, depth 112 m, mud and sand – 20 specimens; icebreaker «Fyodor Litke», 29.IX.1948, station 183, 80º30′ N, 90º03′ E, depth 174 m, mud – 11 specimens; Laptev Sea: R / V «Polarstern», 07.IX.1993, station 43, 77º24′ N, 133º32′ E, depth 55 m – 16 specimens ; East-Siberian Sea: R / V «Ivan Kireev», 2004, station 87, 69º31′ N, 170º25′ E, depth 11 m – 1 specimen ; station 106, 70º28′ N, 171º36′ E, depth 31 m – 1 specimen.

D e s c r i p t i o n. Shell wide-cylindrical, up to 11.5 mm height, spiral striations very narrow, engraved, apex impressed and wide, mostly umbilicated, columellar margin narrow, oblique ( Figs 7G–J ).

Anatomy. Male copulatory system consists of the narrow prostate and long penial sac, which is joined with prostate by a narrow proximal part ( Fig. 3A ). Lateral teeth have uneven denticles, which do not form a plate on the base of the tooth ( Figs 7A, E ). Rachidians bilobate, slightly convex, equipped with short widely spaced denticles on cutting edge, upper-lateral ends without notches ( Figs 7B–D ).

D i s t r i b u t i o n. Arctic species, distributed from Baffin Bay eastward to the East-Siberian Sea.

N o t e s. C. scalptus differs from both C. occultus and C. validus in shell, penial and radular morphology (see Table 1 ). It is not found to the east of the East-Siberian Sea.

Figures

Fig. 3. Male copulatory system: Cylichnoides scalptus, Laptev Sea (A); Cylichnoides densistriatus, Russian Polar Expedition 1901–1903, no data (B); Cylichnoides occultus, Novaya Zemlya, Matochkin Strait (C); Cylichnoides validus, Laptev Sea (D) and Chukchi Sea, «Vega» expedition (dorsal view (E), ventral view (F)). Abbreviations: m – muscle fibers, p.f – folds of penial sheath, others like to Fig. 2. Scale bar: A, D–F – 1 mm; B, C – 0.5 mm.

Fig. 6. Cylichnoides scalptus, shell: Kara Sea, «Fyodor Litke», station 183 (A–E); Barents Sea, R/V «Persey», station 862 (F, G) and station 866 (H) (ventral view: A – 10.2 mm, B – 9.9 mm, C – 9.5 mm, D – 5.3 mm, F – 5.0 mm, H – 10 mm; apical view: E, G). Cylichnoides densistriatus, shell: Kotelny Isl., New Siberian Islands, 1903 (I, J); Laptev Sea, Kondrat’evsky Il., 1973 (K, L), ventral view (I – 5.6 mm, L – 4 mm), apical view (J, K). Scale bar: E, G, J, K – 1.0 mm.

Fig. 7. Cylichnoides scalptus: Kara Sea, 1948: radula (A–F), shell sculpture (G–J), (B–D – rachidian tooth, denticles of the internal lateral tooth, E – denticles of the internal lateral tooth, F – outer lateral teeth). Cylichnoides densistriatus (K, L): radula (K), shell sculpture (L). Scale bar: A – 100 µm; B – 40 µm; C, F, K – 50 µm; D – 30 µm; E – 10 µm; G – 500 µm; H, I, L – 200 µm; J – 400 µm.