Leucosyrinx oliverioi Kantor & Fedosov & Puillandre 2025, sp. nov.

Leucosyrinx oliverioi sp. nov. urn:lsid:zoobank.org:act: A5E2AB47-6BEB-4DB7-A66F-8A24EE96FA18 Figs 9G–L, 10A Etymology The species is named after Marco Oliverio (Sapienza University of Rome, Italy), world known specialist in phylogeny and taxonomy of molluscs and our companion of many years in expeditions organized by MNHN. Material examined Holotype (sequenced) SOLOMON ISLANDS • NW Santa Isabel I.; 7°45′ S, 157°38′ E; depth 930–977 m; SALOMON 2, stn CP2216; MNHN-IM-2007-17928. Other material (all sequenced) PAPUA NEW GUINEA • 1 lv; Kimbe Bay; 5°21′ S, 150°45′ E; depth 490–715 m; BIOPAPUA, stn CP3679; MNHN-IM-2009-17078. SOLOMON ISLANDS • 1 lv; Guadalcanal; 9°25′ N, 160°32′ E; depth 537–619 m; SALOMONBOA 3, stn CP2773; MNHN-IM-2009-6103 • 1 lv; E of Malaita; 8°41′ N, 161°04′ E; depth 556–864 m; SALOMONBOA 3, stn CP2800; MNHN-IM-2009-18960. VANUATU • 1 lv; Big Bay; 14°55′ N, 166°56′ E; depth 667–750 m; BOA1, stn CP2422; MNHN-IM-2007-17690. Description MEASUREMENTS (holotype). SL 37.5 mm, AL (with canal) 18.6 mm, AL (without canal) 12.8 mm, SW 12.9 mm. SHELL (holotype). Shell medium-sized, broad fusiform, with high spire, uniformly light yellow in color, thin. Nearly 10 distinctly roundly angled at shoulder teleoconch whorls, with slightly concave, nearly straight subsutural ramp. Paucispiral protoconch of about 1.5 evenly rounded strongly convex whorls, tan. Distinct slightly adpressed suture. 13 distinct, strong oblique, and rounded axial folds on shoulder of penultimate whorl and 12 on antepenultimate whorl. On last whorl folds present only on apertural side, disappear on dorsal side. Folds fade on subsutural ramp, hardly reach lower suture on penultimate whorl, equally pronounced on all teleoconch whorls except last one. Weak spiral sculpture, hardly discernible on subsutural ramp, below shoulder of very weak, low, rounded, wavy cords, with interspaces narrower than cords’ width. Numerous thin, prominent on subsutural ramp growth lines. Shell base moderately curving, smooth transition to long, straight rather broad canal. Narrow, elongate-oval aperture, poorly differentiated from canal, outer lip fragile, partially broken. Inner lip is slightly concave, nearly straight. Columellar and parietal sides with narrow, distinct callus, of same color as remaining part of last whorl. Moderately deep, subsutural, broadly arcuate anal sinus extends across subsutural ramp, confluent with large forward extension of outer lip. RADULA (Fig. 10A; studied in holotype). Short, comprises around 30 rows of teeth, 8–9 nascent. Marginal teeth duplex, ~470 µm in length (3.7% AL without canal). Major limb narrow lanceolate in dorsal view, curved. Accessory limb relatively broad, constitutes slightly over half of tooth width, ~0.8 of total tooth length, inserted into distinct deep socket on dorsal side of major limb. DNA diagnosis (based on 5 cox 1 sequences) ‘C’ in site 281, ‘T’ in site 364, ‘G’ in site 559. Remarks The holotype has a broader shell than other studied specimens, so that intraspecific variability exceeds interspecific when comparing the species with L. schepmani sp. nov. The axial folds are weaker or absent on the posterior part of the last whorl in all specimens. The spiral cords are very weak below the shoulder, but better pronounced on the shell base and canal. The species is very similar, hardly distinguishable conchologically from L. schepmani sp. nov., and no clear morphological gap was found. Distribution Vanuatu, Solomon Is., Papua New Guinea, 490– 930 m.