Ascalista saipanensis, 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 : 354

Ascalista saipanensis sp. nov.

Figures 1 A–F

Type Material. Holotype LACM 2709, 1 Paratype CKM, 1 Paratype MSF fa175.

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 moderate size for genus, up to 3.3 mm; biconical, elongate. Protoconch paucispiral, bulbous, of 1.4–1.5 smooth whorls. Transition to teleoconch indistinct. Teleoconch of 3.2–3.3 flattened whorls; suture slightly impressed. Surface smooth apart from basal cords, clearly present on last whorl, extending to mid-apertural height. Aperture very narrow, elongate, 45–50% of shell height. Outer lip slightly thickened, bearing continuations of basal cords on abapical end. Inside not denticulate, with clear, smooth rim and weak sinus on adapical end. Columellar callus with pronounced sharp edge, inside not denticulate. Parietal callus weak. Siphonal canal very short, half-open, slightly recurved. Teleoconch whorls translucent, off-white, with network of faint brown axial zigzag lines; band of irregular white spots just below suture. Similar band, with smaller white spots, just above suture, continuing at mid-height of last whorl. Additional band of white spots just above basal cords on last whorl. Protoconch white to off-white. Aperture and columella white. Radula not studied. Height of holotype: 3.3 mm.

Remarks. Until now the genus Ascalista had been known by only two members: the widespread Indo-Pacific species Ascalista polita (G. & H. Nevill, 1875) (figs 1 I–J), and Ascalista letourneuxi Monsecour & Monsecour, 2015 (figs 1 G–H) from the Austral Islands, French Polynesia. Ascalista saipanensis can easily be distinguished from A. polita by its wider shape and paucispiral protoconch. Ascalista saipanensis is distinguished from A. letourneuxi as well by its smaller size, narrower teleoconch and less bulbous protoconch.

Etymology. Latin adjective formed from the type locality, Saipan.

Figures

FIGURE 1. A–F, Ascalista saipanensis sp. nov.; A–B, Holotype. LACM 2709, 3.3 mm; C–D, Paratype 1. CKM, 3.1 mm; E–F, Paratype 2. MSF fa175, 3.0 mm; G–H, Ascalista letourneuxi Monsecour & Monsecour, 2015, French Polynesia, Austral Islands, Rapa Island, Paratype CKM, 4.0 mm; I–J, Ascalista polita (G. & H. Nevill, 1875), Philippines, Mactan Island, Punta Engano, CKM, 3.6 mm; K–L, Euspiralta santoensis Monsecour & Pelorce, 2013, Vanuatu, Segond Channel, CKM, 3.2 mm; M–R, Euspiralta okinawaensis sp. nov.; M–N, Holotype. LACM 3807, 2.7 mm; O–P, Paratype 1. LACM 3808, 2.8 mm; Q–R, Paratype 2. MNHN-IM-2018-1777, 2.9 mm.