Gymnobela agassizi (A.E.Verrill & S.Smith, 1880)

Criscione, Francesco & Hallan, Anders, 2024, Integrative taxonomy of Gymnobela and Pontiothauma (Conoidea: Raphitomidae) from Australian waters provides more evidence of transoceanic distribution in deep-sea gastropods, Journal of Natural History 58 (37 - 40), pp. 1429-1459 : 1449

Gymnobela agassizi (Verrill and Smith, 1880) (PSH G1)

( Figures 3 A-B, 6A)

Pleurotoma (Pleurotomella) agassizi Verrill and Smith, 1880 – Verrill 1880: 394; Verrilll 1882: 454, pl. 57, Fig. 3–3a

Pleurotoma (Pleurotomella) brychia Watson, 1881 – Watson 1881: 451; 1886: 335, pl. 19, fig. 4

Pleurotomella vitrea Verrill, 1885 – Verrill 1885: 414, pl. 44, fig. 6

Pleurotomella agassizi var. permagna Dall, 1890 – Dall 1890: 308

Material examined

Australia, New South Wales, Jervis CMR (− 35.333°S, 151.258°E), IN2017_ V03 _056, 2650– 2636 m, AMS C .519355.

Distribution

North Atlantic and Jervis CMR off the coast of NSW.

Remarks

This species was previously known from its shell only and some minor details of the external anatomy of the animal ( Bouchet and Warén 1980, p. 50).

We provide below some further anatomical details. Animal white. Penis large, coiling clockwise, cylindrical to slightly tapering distally. Cephalic tentacles short, somewhat cylindrical, tip blunt; eyes minute. Venom apparatus: proboscis extremely long, coiled; venom gland convoluted, long; muscular bulb elongated, pearlescent. Radula of hypodermic teeth, relatively straight, tightly rolled; approximately 150 µm in length; barbs absent; adapical opening long; ventral side forming blade approximately 1/6 of length of tooth; base wide, angular, with lateral process; texture rugose; basal opening large, subcircular. Ligament long, rather broad.

Apart from its slightly more rounded whorl profile and its weaker ribs, the shell of this species is very similar to that of G. engonia and G. verecunda – from which, however, it can be easily distinguished by its dark orange-stained columella.

Figures

Figure 3. Shells of Gymnobela primary species hypotheses (PSHs)/species studied herein. (A) G1/ G. agassizi (Verrill and Smith, 1880), Australian Museum (AMS) C.519355; (B) G. agassizii (Verrill and S. Smith, 1880), holotype UNSM 37828; (C) G. engonia (Verrill, 1884), holotype Smithsonian National Museum of Natural History (USNM) 3483; (D) G2/G. engonia AMS C.594980; (E) G2/G. engonia AMS C.593510; (F) G2/G. engonia AMS C.482287; (G) G2/G. engonia AMS C.482286; (H) G2/G. engonia AMS C.571816. Scale bar: A–D, F–H = 10 mm; E = 5 mm.