Gymnobela angulosa Sysoev, 1988

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 : 1449-1450

Gymnobela angulosa Sysoev, 1988 (PSH G3)

( Figures 4H–K , 6D )

Gymnobela angulosa Sysoev, 1988 – Sysoev 1988, p. 965 –967; pl. 2, figs. 1–2; pl. 3, fig. 1

Holotype ( Figure 4H ). Tasman Sea (− 39.950°S, 165.130°E), Station no. 3156, 5525 m, RV Vityaz, ZMMU Lc-22363.

Material examined

Other material: Australia, Tasmania /Victoria, Bass Strait (− 39.552°S, 149.553°E), IN2017_ V03 _030, 4197– 4133 m, 1 wet ( AMS C.571648), 1 wet ( AMS C.571649); Africa, Guinea, Guinea Basin, M 63–2, Station 94–8 EBS (0.630°N, −6.430- 6° 25’ 48”W), M 63–2 (94–8), 5151- m, 1 wet ( ZSM mol_20070770) .

Distribution

N Pacific Ocean (off Japanese Archipelago); Tasman Sea (Bass Strait), Central Atlantic (off western Africa).

Remarks

At the time of writing, the holotype of this species could not be located by staff of the Zoological Museum of Moscow University ( ZMMU), and all observations were conducted on the only available photograph of its shell ( Figure 4H ) . The shell of G. angulosa ( Figures 4H–K ) is similar to that of G. mitrodeta ( Figure 8G ), differing by its taller spire and more cylindrical whorl profile.

As no description of the anatomy is available for this species [except for a figure of the radula of the holotype ( Sysoev 1988, pl. 3, fig. 1)], further anatomical details (based on AMS C.571648) are given below. Animal pale blue. Cephalic tentacles short, blunt; eyes very small. Venom apparatus: proboscis long, coiled; venom gland very long, convoluted; muscular bulb moderately large, elongate-ovate, pearlescent. Radula of hypodermic teeth, straight, tightly rolled; approximately 150 µm in length; adapical opening long; ventral side forming blade approximately 1/5 of length of tooth; base wide, angular, with lateral process; texture rugose; basal opening large, subcircular, unrestricted.

Figures

Figure 4. Shells of Gymnobela primary species hypotheses (PSHs)/species studied herein. (A) G. frielei (Verril, 1885), holotype Smithsonian National Museum of Natural History (USNM) 44653; (B) G4/ G. frielei Australian Museum (AMS) C.571666; (C) G4/G. frielei AMS C.571702; (D) G4/G. frielei AMS C.482314; (E) G4/G. frielei AMS C.571812; (F) G4/G. frielei AMS C.571677;(G) G4/G. glaucocreas (Barnard, 1963), holotype Iziko South African Museum (ISAM) A9821; (H) G3/G. angulosa Sysoev, 1988, holotype Zoological Museum of Moscow University (ZMMU) Lc-22363 (I) G3/G. angulosa AMS C.571649; (J) G3/ G. angulosa AMS C.571648; (K) G3/G. angulosa, Bavarian State Collection of Zoology (ZSM) mol 20070770. Scale bar = 10 mm.

Figure 6. Hypodermic teeth of primary species hypotheses (PSHs)/species studied herein. (A) G1/ Gymnobela agassizi (Verrill and Smith, 1880), Australian Museum (AMS) C.519355; (B) G2/Gymnobela engonia, AMS C.482287; (C) G3/Gymnobela angulosa Sysoev, 1988, Bavarian State Collection of Zoology (ZSM) mol 20070770; (D) G3/Gymnobela angulosa Sysoev, 1988 AMS C.571648; (E) G4/ Gymnobela frielei (Barnard, 1963) AMS C.482314; (F) P1/Pontiothauma sp. AMS C.482298; (G) P2/ Pontiothauma transregna sp. n. paratype AMS C.519398. Scale bar: A–E = 50 µm; F–G = 100 µm.

Figure 8. Shells of Gymnobela species vouchers. (A) G. bairdii (Verrill and Smith, 1884), syntype Smithsonian National Museum of Natural History (UNSM) 37824; (B) G. rotundata Sysoev, 1990, holotype Zoological Museum of Moscow University (ZMMU) Lc 5718; (C) G. abyssorum (Locard, 1897), lectotype Muséum National d’Histoire Naturelle (MNHN) IM-2000-2750; (D) G. chyta (Watson, 1881), holotype Natural History Museum of the United Kingdom (NHMUK) 1887.2.9.1108; (E) G. granulisculpturata Sysoev, 1990, holotype ZMMU Lc 5725; (F) G. verecunda (Barnard, 1963), lectotype ISAM A9697; (G) G. mitrodeta Sysoev, 1997, holotype MNHN IM-2000-3121; (H) G. laticaudata Sysoev, 1990, holotype ZMMU Lc 5735; (I) G. engonia figured in Bouchet and Warén 1980 (fig. 123). Scale bar: A, C, F–G, I = 10 mm; B, H = 3.3 mm; D–E = 5 mm.