Siphonalia cassidariaeformis ( Reeve, 1846 )

Kantor, Yuri, Kosyan, Alisa & Sorokin, Pavel, 2020, On the taxonomic position of Phaenomenella Fraussen & Hadorn, 2006 (Neogastropoda, Buccinoidea) with description of two new species, Zoosystema 42 (3), pp. 33-55 : 48-51

Siphonalia cassidariaeformis ( Reeve, 1846)

( Figs 9 A-C; 10; 11A)

Buccinum cassidariaeformis REE•E, 1846: Pl. 2, sp. 11..

MATERIAL EXAMINED. — Japan • 2 lots, 3 specimens; Off Hashima, Miyazaki Prefecture, Kyushu; 10.V.1996 (no. 1, Fig. 9A ); Off Atsumi Peninsula , Aichi Prefecture; 30 m; 13.V.2001 (nos. 2, 3, Figs 9B, C ) .

COMPLEMENT TO DESCRIPTION

Radula

Radula studied in three specimens. Rather similar in all specimens ( Fig. 11A, B ); central tooth with rectangular basal part and weakly arcuate anterior margin and three medium long triangular broad cusps, central one equal in length but slightly narrower than lateral ones. Lateral teeth tricuspate with weakly curved, nearly straight basal side, attached to membrane. Outermost cusp recurved, medium long, inner cusp weakly recurved, about 2/3 of outer cusp length. Intermediate cusp shortest, situated closer to inner cusp.

D, S. pfefferi no. 2. Scale bars: 200 µm.

Anatomy

Soft body (no. 1, female, Fig. 10A, B, E, F , no. 2, female, Fig. 10C ) with approximately 3 whorls. Head short and broad, with short contracted tentacles. Eyes small, situated at small lobes in the middle of tentacles ( Fig. 10B, C , eyes). Foot contracted, with very narrow propodium and large operculum with terminal nucleus. Penis of spm. no. 3 ( Fig. 10D ) medium long, flattened, contracted, with small (contracted) rounded seminal papilla at the top, surrounded by circular fold of skin. Mantle with very long siphon in dissected specimens (longer than half mantle width).

Digestive system. Proboscis half everted out of rhynchodaeum, thick, contracted ( Fig. 10E, F , pr). Proboscis retractors (prr) attached to rhynchodaeum along both sides of anterior oesophagus (mostly on its right side), connecting rhynchodaeum to lateral walls of body haemocoel. Anterior oesophagus short and wide, dorso-ventrally flattened, along ventral side of proboscis ( Fig. 10E, F , aoe) into relatively small rounded valve of Leiblein ( Fig. 10F , vl), situated immediately anterior to nerve ring ( Fig. 10F , nr). Salivary glands medium small (about 0.25 proboscis length) ( Fig. 10E, F , sg), with very thin strongly convoluted salivary ducts ( Fig. 10F , sd) following along anterior oesophagus. Gland of Leiblein large ( Fig. 10E, F , gl), following along thick, round in section posterior oesophagus ( Fig. 10E, F , poe). Stomach spanning about 0.3 whorl ( Fig. 10G ). Posterior mixing area not large in spm. no. 1, large in spm. no. 2 ( Fig. 10G, I , pma). Posterior oesophagus and intestine medium wide in both specimens. Opening of posterior duct of digestive gland (found in spm. no. 2) located near oesophageal opening ( Fig. 10I , pdg), opening of anterior duct (found in spms. nos. 1 and 2) located near beginning of intestine. Inner stomach wall between two openings with longitudinal fold ( Fig. 10H , lfl), lined with low oblique folds, remaining part of inner and outer stomach walls lined with moderately high transverse folds.

Figures

FIG. 9. — Shells of studied Siphonalia spp.: A-C, S. cassidariaeformis (Reeve, 1846): specimen no. 1 (A), specimen no. 2 (B), specimen no. 3 (C); D, E, S. pfefferi G. B. Sowerby III, 1900; D, specimen no. 1; E, specimen no. 2. Scale bar: 10 mm.

FIG. 11. — Radulae of Siphonalia spp. A, S. cassidariaeformis (Reeve, 1846) no. 1; B, S. cassidariaeformis no. 2; C, S. pfefferi G. B. Sowerby III, 1900 no. 1;

FIG. 10. — Anatomy of Siphonalia cassidariaeformis (Reeve, 1846): A, B; ventral (A) and dorsal (B) views of body of specimen no. 1, removed from the shell; C, cephalopodium of no. 2, front view; D, penis of no. 3; E, F, foregut of no. 1, with right salivary gland in original position (E) and removed (F); G, stomach of no. 2, external view; H, stomach of no. 1, opened dorsally; I, stomach of no. 2, opened dorsally. Abbreviations: see material and methods. Scale bars: A-F, 10 mm; G, I, 5 mm; H, 1 mm