Paralepetopsis bathyalus Hoffman & Little, 2025

Paralepetopsis bathyalus Hoffman & Little sp. nov.

Fig. 3 View Fig .

Zoobank LCID: urn:lsid:zoobank.org:act:411077AB-6C98-422E-A455-17BFE8841F10 .

Etymology: After the habitat in a bathyal (palaeo-) depth range.

Type material: Holotype, SMF373134 About SMF . Paratypes, 11 shells, SMF373131 About SMF ; seven shells, SMF373132 About SMF ; one shell, SMF373135 About SMF ; five shells, SMF 373136 About SMF ; four shells, SMF373137 About SMF ; one shell, SMF373133 About SMF . All 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, thin, solid, limpet shell, oval apertural outline, apex anterior of midline. Protoconch simple exposed whorl, smooth sculpture, often eroded in adult specimens.

Dimensions. — Holotype height 2.5 mm, length 3.8 mm, width 1.2 mm. Shells in type set maximum length 5 mm, height 3 mm, width 1.6 mm.

Description. —Protoconch single stage only, only present on juvenile shells, smooth, planispiral aligned along major height and length axes, 30% from anterior margin, shell leaning posteriorly, fused with teleoconch. Transition to teleoconch clear by change in sculpture, margin sharp. Length 200 μm. Teleoconch convex outline on all margins in dorsal view, anterior margin highest convexity, shell broader posteriorly. Apical angle in side view 120°; anterior outline short, straightened; several convex stages posteriorly. Apex in adult shells with oblong scar and imprint of lost protoconch posteriorly; often worn apex. Sculpture with fine irregular growth lines, fine radial ridges, frequently with nodules at interfaces with major growth stages. Margin smooth, sharp. Internally smooth, glossy, with inconspicuous imprint of muscle. Deep smooth pit at apex.

Remarks.—Eight species in the genus Paralepetopsis have been described from hydrothermal vent and seep habitats in the Atlantic and the Pacific Ocean ( McLean 1990, 2008; Beck 1996; Warén and Bouchet 2001, 2009; Chen et al. 2023). Paralepetopsis floridensis McLean, 1990 , has a near identical protoconch compared to Paralepetopsis bathyalus Hoffman & Little sp. nov., but the outline is more oval and it has a stronger radial sculpture ( McLean 1990). Beck (1996: 89–90, pl. 1) described Paralepetopsis rosemariae Beck, 1996 , based on a single specimen from a seamount in the western Pacific; the decapitated shell has a raised outline with little sculpture apart from a few major growth stages. The eastern Pacific Paralepetopsis tunnicliffae McLean, 2008 , has a similar morphology compared to Paralepetopsis bathyalus Hoffman & Little sp. nov., but it has a strong radial sculpture ( McLean 2008: 18–19, fig. 2A). The Mid-Atlantic Ridge hydrothermal vent species Paralepetopsis ferrugivora Warén & Bouchet, 2001 , has a strong radial as well as concentric sculpture ( Warén and Bouchet 2001: 123–124, fig. 2e–f). The northwestern Pacific seep species Paralepetopsis lepichoni Warén & Bouchet, 2001 , is most similar to Paralepetopsis bathyalus Hoffman & Little sp. nov., but has a coarse as well as fine radial sculpture ( Warén and Bouchet 2001: 125, figs. 2c, 5af). The eastern Atlantic seep species Paralepetopsis sasakii Warén & Bouchet, 2009 , has a coarse radial sculpture and a similar protoconch ( Warén and Bouchet 2009: 2331–2332, fig. 3). Paralepetopsis polita Chen et al., 2023 , from the South China Sea has a polished shell and all known specimens lack a protoconch. Paralepetopsis bathyalus Hoffman & Little sp. nov. has co-marginal ridges with a few growth stages and juveniles show a protoconch. Chen et al. (2023) found a mitochondrial molecular sequence (COI) of Paralepetopsis polita similar to that of Lepetidae , but radular characteristics similar to those in Neolepetopsidae .

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