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

Leucosyrinx placaisae sp. nov. urn:lsid:zoobank.org:act: DB43FF29-2D14-4ECF-8D2D-8975A115C0EC Figs 29F, 31A–F Etymology The species is named after Danielle Plaçais, a volunteer in the molluscan team of MNHN of many years. Material examined Holotype (sequenced) INDIAN OCEAN • Walters Shoal; 33°55′ S, 44°03′ E; depth 1588–1714 m; MD208 (Walters Shoal), stn CP4914; MNHN-IM-2013-48114. Other material (sequenced) INDIAN OCEAN • 1 lv; same data as for holotype; MNHN-IM-2013-48112. Description MEASUREMENTS (holotype). SL 29.9 mm, AL (with canal) 15.7 mm, AL (without canal) 9.1 mm, SW 11.2 mm. SHELL (holotype). Shell medium-sized, slender, fusiform, with medium high spire, light yellow-orange, shell base and canal lighter colored. Protoconch missing. 6.5 remaining distinctly angular on shoulder teleoconch whorls, with subsutural ramp strongly concave on all whorls. Distinct, shallowly impressed suture. 15 strong, oblique axial folds on and below shoulder on last whorl and 12 on penultimate whorl. Folds fade on subsutural ramp, reach lower suture on teleoconch whorls, extend to last whorl periphery and upper shell base. Relatively distinct spiral sculpture of similar in width, slightly sinuous cords over entire shell surface, including subsutural ramp. Intervals between cords narrower than cords’ width. 10 cords on subsutural ramp of last whorl. Shell base moderately convex, rapidly narrowing towards medium long weakly curving canal. Narrow-oval aperture, poorly differentiated from canal. Thin columellar and parietal callus of same color as remaining shell. Moderately deep, subsutural, broadly arcuate anal sinus extends across subsutural ramp, confluent with large forward extension of outer lip. Operculum oval leaf-shaped, with a terminal nucleus. RADULA (Fig. 29F; studied in MNHN-IM-2013-48112). Marginal teeth duplex, ~250 µm in length (4.6% of AL without canal). Major limb narrowly lanceolate, slightly curved. Accessory limb nearly twice as narrow, ~0.75 of total tooth length, inserted into shallow but distinct socket on dorsal side of major limb. DNA diagnosis (based on 2 cox 1 sequences) ‘C’ in site 59, ‘C’ in site 250, ‘T’ in site 328. Remarks The species is represented in our material by two specimens only. The second specimen is smaller than the holotype (SL 18.6 mm), and differs in a relatively broader shell and paler coloration. The species is most similar to L. exulans, differing in a lower spire as well as in a more angulated shoulder. The shell of the new species is also much paler than that of L. exulans. Both species are phylogenetically not closely related. Distribution The species is known from the type locality.