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

Leucosyrinx lemarcisi sp. nov. urn:lsid:zoobank.org:act: ED2EA493-88AF-491B-841F-2CF0E71B95CA Fig. 4G–J Etymology The species is named after Thomas Lemarcis, member of the ERC “HYPERDIVERSE” team, for his contribution to the neogatropod molecular phylogeny. Material examined Holotype (sequenced) SOCIETY ISLANDS • Moorea; 17°33′ S, 149°55′ E; depth 800–830 m; TARASOC, stn DW3467; MNHN-IM-2007-38823 Other material (all sequenced) SOCIETY ISLANDS • 1 lv; Bora Bora; 16°35′ S, 151°44′ E; depth 1013–1060 m; TARASOC, stn DW3417; MNHN-IM-2007-39255 • 1 lv; Bora Bora; 16°32′ S, 151°48′ E; depth 798–830 m; TARASOC, stn DW3419; MNHN-IM-2007-38850 • 1 lv; Moorea; 17°27′ S, 149°48′ E; depth 1000– 1145 m; TARASOC, stn DW3462; MNHN-IM-2007-38674. Description MEASUREMENTS (holotype). SL 26.0 mm, AL (with canal) 13.5 mm, AL (without canal) 8.7 mm, SW 8.6 mm. SHELL (holotype). Small, fusiform, with high spire, fragile, of uniform light tan color.About 8 teleoconch whorls. Paucispiral protoconch of about 2 rounded whorls. Transition between protoconch and teleoconch indistinct due to protoconch and earliest teleoconch whorls erosion. Teleoconch whorls angled at shoulder, with distinctly concave subsutural ramp. Distinct, shallow, impressed suture. 12 strong, oblique, broad, rounded axial ribs on body whorl, 14 on penultimate one. Ribs rapidly disappear on subsutural ramp, slightly weaken towards lower suture, disappear at body whorl periphery. Intervals between ribs slightly broader than ribs themselves. Weak spiral sculpture of low, rounded, and narrow cords over entire shell surface, including subsutural ramp, slightly stronger on shell base and canal Numerous, thin growth lines, prominent on subsutural ramp. Shell base weakly curving, smooth transition to long, straight canal. Narrow, elongate-oval aperture, poorly differentiated from canal. Inner lip nearly straight. Columellar and parietal sides with narrow, distinct callus. Moderately deep, subsutural, broadly arcuate anal sinus extends across subsutural ramp, confluent with large forward extension of outer lip. RADULA. Not examined. DNA diagnosis (based on 4 cox 1 sequences) ‘G’ in site 73, ‘T’ in site 181, ‘C’ in site 544, ‘C’ in site 613. Remarks In shell outline this new species is very similar to Leucosyrinx floraecharlottae sp. nov., differing in a smaller size, less numerous axial ribs on shoulder and in stronger pronounced spiral cords on subsutural ramp. There is also a certain similarity to L. herosae sp. nov., which is much larger (up to 47 mm).Another similar species is Leucosyrinx sp. 18, represented in our material by two specimens. The new species differs from Leucosyrinx sp. 18 in having a relatively lower spire. None of them are phylogenetically related to L. lemarcisi sp. nov. Distribution Society Is., 800–1013 m.