Mitropsis noduliferus, Monsecour & Raines, 2024

Monsecour, Kevin & Raines, Bret K., 2024, New species and genus of Columbellidae (Gastropoda: Buccinoidea) from the Western Pacific, Zootaxa 5514 (4), pp. 353-367 : 357

Mitropsis noduliferus sp. nov.

Figures 2 K–N

Type Material. Holotype LACM 2907 , 1 Paratype MNHN-IM-2018-1779 , 1 Paratype CKM, 1 Paratype MSF fa178.

Type Locality. Northern Mariana Islands, Saipan, The Grotto , 15.2702 o N, 145.8346 o E, 30 m deep.

Distribution. Currently only known from the type locality.

Description. Shell of average size for genus, up to 4.6 mm; fusiform, elongate.Protoconch paucispiral, elongated, of 1.4–1.5 smooth whorls. Transition to teleoconch clearly visible. Teleoconch of 4.3–4.6 flattened whorls; suture slightly incised.Axial sculpture of 14–15 strong ribs; interspaces narrower than ribs. Spiral sculpture of rounded low cords with narrow interspaces. Early whorls have 3 cords; penultimate whorl with 4 cords; last whorl with 8 cords, extending into basal cords on abapical end. Intersections of axial ribs and spiral cords giving shell surface nodulose appearance. Basal cords extending to just below adapical edge of columella. Aperture narrow, elongate, slightly Sshaped, 43–48% of shell height. Outer lip slightly thickened, bearing continuations of spiral cords and basal cords. Inside with clear sinus on adapical end; 6 denticles, diminishing in strength toward abapical end, adapical denticles partially fused. Columellar callus with 4 denticles, abapically much weaker. Parietal callus clearly present. Siphonal canal short, open, slightly recurved. Teleoconch whorls, off-white, with cream zone below suture and on abapical end of last whorl. Protoconch off-white to cream, with darker nucleus. Aperture and columella off-white. Radula not studied. Height of holotype: 4.55 mm.

Remarks. This genus was previously only known from the type species Mitropsis paumotensis from French Polynesia. Mitropsis noduliferus differs from M. paumotensis by its slightly smaller size, less incised suture, stronger spiral sculpture and lower number of denticles in the aperture. The lectotype of M. paumotensis (ANSP 28756) is figured online (http://clade.ansp.org/malacology/collections/details.php?mode=details&catalognumber=28756), but it is a worn specimen without protoconch and not much sculpture left. Boutet et al. (2020: p 348) figured a nice specimen of M. paumotensis . The specimen figured in Monsecour & Monsecour (2018) as M. paumotensis (plate 4, figs A–B), is incorrectly identified and most likely represents a third species of Mitropsis , similar to M. noduliferus . However, M. noduliferus also differs from that species by its less incised suture and weaker spiral ribs.

Etymology. Latin nodulifera meaning knobby. Refering to the nodulose spiral elements.

Figures

FIGURE 2. A–F, Mitrella harryleei sp. nov.; A–B, Holotype. LACM 2710, 5.0 mm; C–D, Paratype 1. LACM 2711, 5.4 mm; E–F, Paratype 2. MNHN-IM-2018-1778, 5.5 mm; G–H, Mitrella philia (Duclos, 1846), syntype MNHN-IM-2000-6404, 5 mm photo credit: MNHN M. CABALLER, PROJET: RECOLNAT (ANR-11-INBS-0004); I–J, Columbella goubini Hervier, 1900, New Caledonia, Lifou, syntype MNHN-IM-2000-6900, 6.3 mm, photo credit: MNHN M. CABALLER, PROJET: RECOLNAT (ANR-11-INBS-0004); K–N, Mitropsis noduliferus sp. nov., K–L, Holotype. LACM 2907, 4.55 mm; M–N, Paratype 1. MNHN-IM-2018-1779, 4.5 mm.