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

Leucosyrinx nodulocordata sp. nov. urn:lsid:zoobank.org:act: 69EE0101-26EA-479D-B457-91403D1CEFCC Fig. 28H–L Etymology From Latin ‘ nodulus ’ – ‘little knot, swelling‘ and ‘ corda ’ – ‘rope, cord’, referring to the nodules, present on major spiral cords on last whorl. Material examined Holotype (sequenced) SOLOMON SEA • Dampier Strait; 5°36′ S, 146° 13′ E; depth 620–780 m; PAPUA NIUGINI, stn CP4013; MNHN-IM-2013-9752. Additional material (sequenced) PHILIPPINES • 1 lv; off Balicasag I., 9°30′ N, 123°42′ E; depth 356–396 m; PANGLAO 2005, stn CP2393; MNHN-IM-2007-42471. Description MEASUREMENTS (holotype). SL 10.4 mm, AL (with canal) 5.4 mm, AL (without canal) 2.9 mm, SW 3.6 mm. SHELL (holotype). Shell small, slender, narrowly fusiform, with medium high spire, off-white, thin, translucent, fragile. Small paucispiral protoconch of about 1.5 smooth microshagreened yellow whorls. Protoconch-teleoconch transition marked by appearance of anal sinus and obtuse medial keel, corresponding to shoulder on later whorls. 6 distinctly angular teleoconch whorls on shoulder with evenly moderately concave subtural ramp on all whorls subsutural ramp. Distinct, shallowly impressed suture. 13 and 12 on last and penultimate whorls strong, slightly oblique axial folds, present on and below shoulder, reaching lower suture on teleoconch whorls. Spiral sculpture of few rather strong cords bellow shoulder, one immediately below shoulder, crossing axial folds, below two similar in strength narrow cords with intervals 4–5 times as broad as cords’ width, forming oval nodules on intersections with lower parts of axial folds. Between cords axial folds not pronounced. Shell base and siphonal canal with 15 more closely spaced cords, with intervals 1–2 times cords’ width. Cords’ width same as of nodulated ones. Subsutural ramp smooth. Shell base weakly convex, slowly passing into long weakly curving canal. Narrow-oval aperture poorly differentiated from canal. Columellar and parietal callus thin, of same color as remaining shell. Medium deep, subsutural, broadly arcuate anal sinus extends across subsutural ramp, confluent with large forward extension of outer lip. Operculum narrow leaf-shaped, with terminal nucleus. RADULA (examined in MNHN-IM- 2007-42471). Typical of the genus. Marginal teeth duplex, ~150 µm in length (5.5% AL without canal). DNA diagnosis (based on 2 cox 1 sequences) ‘C’ in site 205, ‘A’ in site 370, ‘A’ in site 565. Remarks Only two specimens of this species were available. The ASAP analysis suggests the presence of two independent sister PSHs included within L. nodulocordata sp. nov.; however, due to the strong similarity in shell morphology, we consider the molecular differences to be geographically related. The second specimen lacks part of the canal, which makes the shell appear more stout. Additionally, only the upper subshoulder keel is nodulated, while the second keel is smooth. This new species is unique due to the presence of nodulated spiral cords below the shoulder, a feature not found in any other species of Leucosyrinx. We are uncertain if the specimens are fully grown, as the larger specimen (holotype) consists of only six teleoconch whorls – a very low number for Leucosyrinx. Distribution Solomon Is. to Philippines, 356– 620 m.