Alvania axistriata Hoffman & Little, 2025

Alvania axistriata Hoffman & Little sp. nov.

Fig. 10 View Fig .

Zoobank LCID: urn:lsid:zoobank.org:act:63375D11-3BF0-4D60-B958-B7D3A0901AC5 .

Etymology: After the axial ribs that are aligned with the spire axis.

Type material: Holotype, SMF373067 About SMF , well preserved shell with protoconch.. Paratypes, three shells, SMF 373063 About SMF ; five shells, SMF373065 About SMF ; twoshells, SMF373068 About SMF ; oneshell, SMF373064 About SMF ; sixshells, SMF373066 About SMF , from the type locality and horizon.

Type locality: Northern Indian Ocean, Krishna-Godavari Basin , Bay of Bengal, offshore eastern India, 15°51.6335’ N, 81°50.2274’ E, 1046 m water depth GoogleMaps .

Type horizon: 16.18–16.88 mbsf level, core NGHP-01-12A; Upper Pleistocene .

Material.— Type material and several specimens from core NGHP-01-12A (for details see Table 1).

Diagnosis.—Small shell with raised rounded outline with pointed apex, fragile, broad ribs and weaker broad spiral cords on shell face, suture deeply impressed.

Dimensions.— Holotype height 2.2 mm, length 1.4 mm. Maximum dimensions of shells in type set as in holotype.

Description.—Protoconch single stage only; raised, slightly over one whorl; embryonic shell smooth; last half whorl with shallow vertical line segments, somewhat spirally aligned, length 10–20 µm, width 2 µm; thin sharp margin. Transition to protoconch clear by change in sculpture. Maximum diameter 470 μm. Teleoconch conical, apical angle 50–60°, two and half convex whorls. Sculpture wide axial ribs, interspaces of comparable width, about 30 ribs on each whorl; fine spiral threads overrunning the ribs; one broad spiral channel high on the shoulder. Base whorl with 6–7 strong spiral cords, fading near periphery. Thickened rim near lip. Aperture orthocline, pyriform, bevelled external lip, thick callus, peristome complete.

Remarks.—We place the specimens in the genus Alvania on the basis of the combination of morphological features, for example size, outline, aperture, sculpture and protoconch. The genus is cosmopolitan, but most diverse in the NE Atlantic and Mediterranean Sea. Alvania stigmata Frauenfeld, 1867 , is a similar species described from the Nicobar Islands. However, that species has 16–18 vertical ribs and 3–4 basal cords and a few subsutural lines; our species has 30 ribs, 6–7 basal cords and one subsutural channel ( Frauenfeld 1867: 12). The Indian Ocean Alvania versoverana ( Melvill, 1893) has a similar outline and size, but its axial ribs are curved and the spiral cords cover the full shell face (Mellvill 1893: 61, pl. 1: 15). Alvania mahimensis ( Melvill, 1893) has a similar outline and size, but its suprasutural sculpture has 3–4 rows of broad nodules (Mellvill 1893: 61, pl. 1: 17). The NE Atlantic Alvania electa ( Monterosato, 1874) is very similar to our species, but has a strong spiral sculpture on the shell face and it lacks the spiral channel on the shoulder ( Bouchet and Warén 1993: 633–634, figs. 1410–1420). Alvania porcupinae Gofas & Warén, 1982 , is also very similar but has a larger protoconch with two whorls ( Bouchet and Warén 1993: 636–638, figs. 1379, 1421–1429).

Stratigraphic and geographic range.— Type locality and horizon only.

Genus Benthonellania Lozouet, 1990 View in CoL

Type species: Benthonellania gofasi Lozouet, 1990 , by original designation; Recent, NE Atlantic.