Cantrainea herosae, 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 : 78-81

Cantrainea herosae sp. nov.

urn:lsid:zoobank.org:act:78AC55FB-2B32-4C73-A868-8F491E1F85B3

Figs 31 , 32A

Diagnosis

Shell thick, trochoid-turbiniform, spire prominent; height up to 7.4 mm; periphery below mid-whorl; base flattened, anomphalous in adult; sculpture of strong spiral cords, three above periphery, one at periphery; subsutural and shoulder cords distinctly beaded; shell surface with silken sheen; base with indistinct spiral lirae; umbilical region covered with glossy extension of parietal callus; aperture roundly quadrate; columella with a low rounded nodule just below its mid-point; interior highly nacreous; shell uniformly milky-white, with pale straw-coloured periostracum.

Etymology

Named for Virginie Héros (MNHN), in recognition of her stalwart contribution to the institution’s Mollusca collection and the Tropical Deep-Sea Benthos programme, over many years.

Material examined

Holotype

WALTERS SHOAL • living specimen; slopes, stn DW4890; 33°09′ S, 43°59′ E; depth 492–588 m; 4 May 2017; DNA tissue sample; MNHN-IM-2013-67292 .

Paratypes

WALTERS SHOAL – slopes • 1 living specimen, juvenile; stn DW4890; 33°09′ S, 43°59′ E; depth 492–588 m; 4 May 2017; SEM protoconch; MNHN-IM-2000-35706 • 1 empty shell; stn DW4890; 33°09′ S, 43°59′ E; depth 492–588 m; 4 May 2017; MNHN-IM-2000-35707 .

Other material

WALTERS SHOAL – slopes • 1 empty shell, subfossil; stn DW4898; 33°09′ S, 44.01′ E; depth 652– 668 m; 6 May 2017; MNHN • 1 empty shell, juvenile; stn DW4900; 33°10′ S, 44°01′ E; depth 660– 670 m; 6 May 2017; MNHN .

Description

SHELL. Thick, relatively small for the genus (height up to 7.4 mm), trochoid-turbiniform, with prominent spire; height slightly greater than diameter (H/D ± 1.03); whorls with strong spiral cords; suture indented, periphery below mid-whorl; base flattened, anomphalous in adult; teleoconch of up to 4.75 whorls. First teleoconch whorl initially with 3 low spiral lirae, but these soon becoming obsolete; early part of second whorl lacking spiral sculpture and bearing only weak, irregular growth-lines; toward end of second whorl a weak angulation develops at mid-whorl, progressively strengthening and becoming distinct shoulder cord during third whorl; two further cords develop toward end of third whorl, one immediately below adapical suture and one between shoulder and abapical suture, these strengthening during fourth whorl, the lower one equal to shoulder cord in strength; a fourth cord at whorl periphery emerges from suture just prior to insertion of outer lip; last adult whorl with low intermediary cord in intervals either side of shoulder cord; axial sculpture indistinct on first two teleoconch whorls, but distinct prosocline pliculae develop on shoulder slope during third whorl; pliculae strengthen during fourth whorl producing distinct beads on subsutural and shoulder cords; pliculae not evident in interval below shoulder, but cord below shoulder evincing weak beading; entire surface of shell with microscopic axial threads giving surface silken sheen. Base flattened, with indistinct spiral lirae; umbilicus narrowly patent in juveniles, but adult specimens with umbilical region covered by glossy extension of parietal callus. Aperture roundly quadrate; peristome interrupted in parietal region; columella oblique to shell axis; outer lip thick, lacking ornamentation; interior highly nacreous, nacre extending over columella and parietal lips; columella with a low rounded nodule just below its mid-point, set back from the edge, mostly in non-nacreous region.

PROTOCONCH ( Fig. 32A ). Large, translucent milky-white; diameter 360–400 μm, ca 1.25 whorls, apical bulb evenly rounded; sculpture somewhat worn, but retaining microscopic superficial granulation and traces of fine, widely-spaced, subspiral lirae; terminal lip weakly convex and very slightly flaring, not thickened.

COLOUR. Shell uniformly milky-white, covered with a thin pale straw-coloured periostracum; spiral cords paler where periostracum worn away.

DIMENSIONS. Holotype, height 7.2 mm, diameter 6.9 mm; largest specimen, height 7.4 mm, diameter 7.2 mm.

OPERCULUM ( Fig. 31E ). White, thickly calcified, somewhat translucent; external surface smooth and glossy, that part adjacent to upper columella and paries thicker and curving slightly outward, no evidence of granulation; inner surface weakly convex, showing tightly multispiral nucleus, but becoming paucispiral toward periphery with final two whorls more rapidly expanding; growing edge broad, tinged with brown.

RADULA AND EXTERNAL ANATOMY. Unknown.

Distribution

Known only from the slopes of Walters Shoal; dredged alive in 492–588 m, on coarse sand with abundant ophiuroids and diverse Cnidaria.

Remarks

Cantrainea herosae sp. nov. is rendered distinctive on account of its prominent spire, shouldered whorls and beaded spiral cords. Cantrainea boswellae (Barnard, 1969) from a depth of 365 m off Cape Point, C. indica (Smith, 1894) from a depth of 1090 m off Sri Lanka, and C. inexpectata Marshall, 1979 from ca 800 m on the Kermadec Ridge, are all larger (height 17.5 mm, 26 mm and 11.5 mm, respectively), have a proportionately less elevated spire with less strongly shouldered whorls and have weaker spiral cords that lack beads. Cantrainea gibbula ( Thiele, 1925) from the Agulhas Bank is of a more similar size (height 8.0 mm), but has more rounded whorls, with more numerous, evenly spaced spiral cords, and the suture descends more strongly prior to the aperture. Perhaps the most similar species is the type species C. peloritana (Cantraine, 1835) from the NE Atlantic and Mediterranean, particularly with regard to its prominent spire and shouldered whorls ( Smiriglio et al. 1992). However, in that species the spiral cords are not as strong and are not beaded.

Some intraspecific variation in sculpture is evident in this species, particularly with regard to the strength of the axial sculpture and the beading on the spiral cords. The single adult paratype ( Fig. 31D ) has weaker subsutural pliculae than the holotype and the beading of the spiral cords is less conspicuous. In addition, it has two low intermediary spiral cords in the interval above the shoulder cord on the last two whorls, instead of one.

Figures

Fig. 31. Cantrainea herosae sp. nov. A–C. Holotype, height 7.2 mm (MNHN-IM-2013-67292). D. Paratype with weakly beaded sculpture, periostracum missing, height 7.4 mm (MNHN- IM-2000-35707). E. Interior (left) and exterior (right) of operculum of holotype, greatest diameter 2.45 mm.

Fig. 32. A. Cantrainea herosae sp. nov., protoconch (paratype, MNHN-IM-2000-35706). B. Parviturbo cicatricosus sp. nov., holotype, protoconch and axial varices on early teleoconch. C–F. Microcollonia miniata sp. nov.C. Protoconch and early teleoconch (paratype, MNHN-IM-2000-35709).D. Operculum, maximum diameter 1.0 mm (paratype, MNHN-IM-2000-35708). E. Radula, half row (ex stn WS07). F. Radula, rachidian and right lateral teeth (ex stn WS07). Scale bars: A–C =100 μm; D =250 μm; E =25 μm; F = 10 μm.