Microliotia alvanioides, Renard & Bouchet, 2003

Renard, Jacques Le & Bouchet, Philippe, 2003, New species and genera of the family Pickworthiidae (Mollusca, Caenogastropoda), Zoosystema 25 (4), pp. 569-591 : 581-582

Microliotia alvanioides n. sp.

( Fig. 8 )

TYPE MATERIAL. — Holotype (dd) and 8 paratypes in MNHN; 1 paratype each SMF 308414 and MZB 31021.

TYPE LOCALITY. — Marquesas Is, off Fatu Hiva, 10°34’S, 138°42’W, 1150-1250 m, MUSORSTOM 9, stn DR1247.

ETYMOLOGY. — The epithet alvanioides is derived from the superficial resemblance to the rissoid genus Alvania .

MATERIAL EXAMINED. — A total of 8 specimens (2 lots).

Marquesas Is. MUSORSTOM 9, stn DR1198, 09°50’S, 139°09’W, 290-320 m, off Hiva Oa, 7 dd (paratypes). — Stn DR1247, 10°34’S, 138°42’W, 1150- 1250 m, off Fatu Hiva, 4 dd (holotype and paratypes).

DESCRIPTION

Holotype ( Fig. 8A, B ). Shell small, rissoiform, consisting of 7.75 whorls. Protoconch ( Fig. 8D ) of 2.25 whorls, globular, protoconch I smooth, protoconch II sculptured in its later part with one strong adapical, and two strong abapical cords, and traces of weaker cords on periphery, protoconch/teleoconch transition marked by broad, deep sinusigera notch, sinus bordered by recurved lip. Teleoconch whorls 5.5, very flat in profile, suture rather deep at bottom of narrow, deep furrow. Sculpture on spire consisting of axial ribs, 13 on second whorl, 18 on last whorl, interspaces as broad as ribs, opisthocline on first three whorls, then orthocline on penultimate whorl, and prosocline on last whorl, intersected by strong spiral cords, one adapical, one abapical, stronger, forming nodular intersections with axial ribs; additional, weaker cords in between, one on penultimate whorl, three and then four on last whorl. Body whorl occupying 62% of total shell height. Base rather convex, sculptured by five thick spiral cords, interspaces narrower than cords, undulating when intersecting axial sculpture ( Fig. 8C ). No umbilicus. Aperture rounded, very prosocline. Spiral cords extending onto thickened peristome varix.

Dimensions

H = 1.75 mm, D = 1.15 mm. REMARKS

Microliotia alvanioides n. sp. resembles very much the type species, M. brandenburgi , from the Miocene of the Paratethys, and differs by having less convex, flat whorls, and fewer and much stronger basal cords.

Figures

FIG. 8. — Microliotia alvanioides n. sp., off Fatu Hiva, Marquesas Is (MNHN); A, B, holotype, apertural and side views, H = 1.75 mm; C, D, paratypes; C, basal view; D, protoconch. Scale bar: D, 100 µm.