Solariella asaphea, 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 : 92-93

Solariella asaphea sp. nov.

urn:lsid:zoobank.org:act:BB1FF786-D3D4-4B52-9CB3-9E928D81A0ED

Fig. 36A–C, H–I

Diagnosis

Shell thin, turbiniform, wider than high, diameter up to 4.1 mm; last adult whorl weakly angled at shoulder; base rounded with wide umbilicus; sculpture of fine, close-set, spiral lirae, ±15 at end of penultimate whorl; first 1.5 whorls with fine, close-set, axial threads with close-set, collabral pliculae developing thereafter; base with similar spiral lirae; uniformly whitish.

Etymology

From the Greek “ asaphes ” (ασαφες) – “indistinct, unclear”; in reference to the rather nondescript features of the shell.

Material examined

Holotype

WALTERS SHOAL • empty shell; slopes, stn DW4900; 33°10′ S, 44°01′ E; depth 660–670 m; 6 May 2017; MNHN-IM-2000-35719 .

Paratypes

WALTERS SHOAL – slopes • 1 empty shell; same collection data as for holotype; MNHN- IM-2000-35720 • 4 empty shells; stn DW4898; 33°09′ S, 44°01′ E; depth 652–668 m; 6 May 2017; MNHN-IM-2000-35721 .

Other material

WALTERS SHOAL – slopes • 2 empty shells; stn DW4899; 33°09′ S, 44°02′ E; depth 707–720 m; 6 May 2017; MNHN .

Description

SHELL. Small (diameter up to 4.1 mm), thin, turbiniform, wider than high; spire whorls rounded and suture strongly indented; last adult whorl weakly angled at shoulder and periphery; periphery below mid-whorl; base rounded, with wide umbilicus; teleoconch of up to 3.5 whorls. First teleoconch whorl with ±7 spiral lirae, increasing to ± 15 at end of penultimate whorl; lirae remain fine and close-set; axial sculpture comprising numerous fine, close-set threads on first 1.5 whorls, with fine regular, collabral pliculae developing thereafter; pliculae and lirae subequal, rendering adapical sculpture finely reticulate ( Fig. 36B, H ); base with similar spiral lirae, though somewhat finer and more close-set, except near umbilicus; pliculae weaken below periphery, becoming little more than fine growth-lines; margin of umbilicus evenly rounded, but spiral lirae slightly stronger and more widely spaced around and into umbilicus. Aperture subcircular; peristome interrupted in parietal region; columella concave, not thickened or reflected; outer lip thin; interior lacking conspicuous nacre, but no fresh specimens available.

PROTOCONCH ( Fig. 36I ). Translucent white; diameter ±360 μm, ca 1.25 whorls, apical beak lacking; mostly smooth, but with traces of fine granulation and widely spaced spiral threads; terminal lip straight, not thickened.

COLOUR. Shell uniformly white to cream-white throughout.

DIMENSIONS. Holotype, height 3.4 mm, diameter 4.1 mm (= largest specimen).

OPERCULUM, RADULA AND EXTERNAL ANATOMY. Unknown.

Distribution

Known only from the slopes of Walters Shoal, at depths of 668–707 m; dredged on substrata of coarse sand with solitary corals; living specimens unknown.

Remarks

Solariella asaphea sp. nov. is superficially similar to three South African species, namely ‘ Spectamen ’ martensi Herbert, 2015 , ‘ Sp. ’ multistriatum ( Thiele, 1925) and ‘ Sp. ’ sulculiferum Herbert, 1987 . However, both ‘ Sp. ’ martensi and ‘ Sp. ’ multistriatum have a much larger protoconch (diameter> 600 μm) and ‘ Sp. ’ sulculiferum is considerably larger (diameter 6.4 mm), has more strongly shouldered whorls and a distinct peri-umbilical angle delineated by a beaded cord ( Herbert 1987b).

Two poorly known taxa from 400 m on the Sapmer Bank Seamount, namely ‘ Solariella ’ dowi Barnard, 1963 and ‘ Solariella ’ palirrous Barnard, 1963, also resemble the present species, but both attain a larger size (diameter 8.5 mm and 6.0 mm respectively). In addition, ‘ S.’ dowi develops two stronger lirae at the end of the third whorl, one below the suture and the other at the shoulder, the former nodular. ‘ S.’ palirrou s has less numerous spiral lirae, a tabulate subsutural zone with retractive pliculae and a narrow umbilicus.

Figures

Fig. 36. A–C, H–I. Solariella asaphea sp. nov. A, C. Apertural and oblique basal views of holotype, diameter 4.1 mm (MNHN-IM-2000-35719). B. Apical view of paratype, diameter 3.3 mm (MNHN- IM-2000-35720). H. Subsutural sculpture, holotype. I. Protoconch (paratype, MNHN-IM-2000-35720). D–E. Bathymophila williamsae sp. nov., paratype (MNHN-IM-2013-67176). D. Oblique view of spire showing detail of apical sculpture. E. Sculptural detail of protoconch. F–G. Phragmomphalina candida sp. nov., paratype (MNHN-IM-2000-35718). F. Oblique view of spire showing sunken suture and detail of apical sculpture. G. Sculptural detail of protoconch. Scale bars: D, F =500 μm; E, G, I= 100 μm; H =200 μm.