Lissotesta wareni, Herbert, 2024

Herbert, David G., 2024, The Vetigastropoda (Mollusca) of Walters Shoal, with descriptions of two new genera and thirty new species, European Journal of Taxonomy 923, pp. 1-119 : 63-65

Lissotesta wareni sp. nov.

urn:lsid:zoobank.org:act:931D472C-26CD-4777-9176-A580973E38BB

Fig. 26A–C, G

Diagnosis

Shell minute, elevated-turbiniform, H/D =0.98–1.2, whorls rounded, base umbilicate; smooth, sculptured only by very fine, widely spaced, spiral threads; threads often more close-set near periphery of base and coarser around and within umbilicus; aperture subcircular, almost radial; outer lip simple; interior not nacreous; protoconch globose and exsert, its suture scarcely evident, surface finely granular.

Etymology

Named for Dr Anders Warén (Swedish Museum of Natural History), in recognition of his enormous contribution to the discovery and documentation of micro-mollusc diversity.

Material examined

Holotype

WALTERS SHOAL • empty shell; slopes, stn DW4886; 33°17′ S, 43°56′ E; depth 573–582 m; 3 May 2017; MNHN-IM-2000-38091 .

Paratypes

WALTERS SHOAL • 5 empty shells; same collection data as for holotype; MNHN-IM-2000-38092 .

Description

SHELL. Minute (height up to 1.0 mm), elevated-turbiniform, H/D= 0.98–1.2; whorls rounded and suture strongly indented; periphery evenly rounded, close to mid-whorl; base rounded and umbilicate; teleoconch of up to 2.25 whorls. Sculpture comprising only very fine, narrow, raised, spiral threads; threads mostly relatively widely spaced, but spacing somewhat variable and threads often more close-set near periphery of base; threads somewhat coarser around and within umbilicus; umbilicus of moderate width. Aperture subcircular, almost radial, orthocline or weakly prosocline, peristome briefly interrupted in parietal region, its edge simple; interior not nacreous.

PROTOCONCH ( Fig. 26G ). Typical of genus; globose and exsert, suture between apical bulb and terminal tube scarcely evident; diameter ±285 μm; sculpture of fine anastomosing granules.

COLOUR. Uniformly translucent milky-white.

DIMENSIONS. Holotype, height 1.00 mm, diameter 0.85 mm (= largest specimen).

Distribution

Known only from the slopes of Walters Shoal, at depths of 573–582 m; dredged on coarse sandy substrata; living specimens unknown.

Remarks

Lissotesta wareni sp. nov. closely resembles L. mammillata (Thiele, 1912) from the Davis Sea, East Antarctica. That species, however, is larger (height at two teleoconch whorls 1.6 mm vs 1.0 mm) and has more crowded spiral threads on the base. Thiele mentioned no spiral threads above the periphery, although these are evident in the illustration provided by Dell (1990). Lissotesta gittenbergeri (van Aartsen & Bogi, 1988) from the upper bathyal in the NE Atlantic, is another similar species, but it has stronger spiral cordlets ( Oliver et al. 2023).

Figures

Fig. 26. A–C, G. Lissotesta wareni sp. nov. A–B. Apertural and oblique basal views of holotype, height 1.0 mm (MNHN-IM-2000-38091). C. Apical view, diameter 0.86 mm (paratype, MNHN- IM-2000-38092). G. Protoconch (paratype, MNHN-IM-2000-38092). D–F, H. Trenchia mcleani sp. nov., holotype (MNHN-IM-2000-38093). D–F. Apertural, oblique and apical basal views, diameter 2.9 mm. H. Protoconch. Scale bars= 100 μm.