Mioawateria ektonos, Morassi & Bonfitto, 2010

Morassi, M. & Bonfitto, A., 2010, New raphitomine gastropods (Gastropoda: Conidae: Raphitominae) from the South-West Pacific, Zootaxa 2526, pp. 54-68 : 60-62

Mioawateria ektonos new species

Figures 2. A–I

Type material: Holotype MNHN 22304 . Paratypes: 1 MNHN 22305 , 1 MZB 45713, 1 ZRC 2981.

Type locality: Solomon Islands, 09°32.6’S 160°37.3’E, 283–305m [SALOMON 1 Stn CP 1859] .

Material examined: only known from the type material.

Description: Shell fusiform to fusiform-biconic (b/l 0.41–0.46; a/l 0.35–0.37). Teleoconch consisting of up to 8 whorls angularly shouldered above mid-whorl. Last whorl strongly excavated with a rather short neck, strongly curved to left. Sutural ramp almost horizontal. Subsutural fold very weak on earlier whorls, absent on later ones. Axial sculpture consisting of narrow, raised axial ribs rather straight below shoulder, prosocline above it. There are 13–16 axial ribs on penultimate whorl; 15–17 on last whorl. Axial ribs crossed by slightly narrower, wide-set spiral cords producing narrow, sharp nodules at points of intersection. Early whorls sculptured by two spiral cords, the upper one at shoulder angle; on later whorls a weak cord appears just above lower suture, developing during growth into a third main cord. On last whorl each interspace between spiral cords may bear a secondary cord. Base of last whorl sculptured by 3–4 spiral cords; 2–5 closely spaced spiral threads occur on the neck. Entire surface covered by coarse axial growth lines. Aperture subrectangular. Columella almost straight above, distinctly curved to left below. Labial callus thin, sculptured by microscopic rows of prickly nodules in its interior part (fig. 2G). Outer lip thin with an extremely weak anal sinus. Protoconch conical, of 2.75–3 whorls; protoconch I covered with minute, dense spiral threads rendered granulose where crossed by even finer axial threads; protoconch II sculptured by opisthocyrt axial riblets extending from suture to suture decussate by oblique threads on anterior two thirds of each whorl. Protoconch breadth: 0.49 mm. Color beige-white.

Dimensions: Holotype 11.8 x 4.6 mm, aperture height 3.9 mm; largest Paratype: 8.7 x 4.0 mm, aperture height 3.2 mm.

Remarks: This species is provisionally designated to the genus Mioawateria . In its high spire Mioawateria ektonos is superficially similar to Magnella andersoni Dittmer, 1960 and P. tornata var. malmii Dall, 1889 but differs from other Mioawateria species in lacking a “moniliform” subsutural fold and in possessing a rather small protoconch (figs. 2H–I). The new species is rather remarkable in that it has a prickly teleoconch sculpture (figs. 2E–F), somewhat reminiscent of members of the genus Raphitoma Bellardi, 1848 . The only similar described species we have been able to find is “ Puha ” sinusigera Powell, 1942, an Early Miocene species from New Zealand of uncertain affinities. Mioawateria ektonos differs from “ Puha ” sinusigera in its much larger size (8.7–11.8 mm vs 5.1 mm in length), more numerous teleoconch whorls (up to 8 vs 4) and fewer protoconch whorls (2.75–3 vs 6) (figs. 2H–I). Both species have a high, stepped spire and resemble Mioawateria in the shape of the teleoconch whorls and in possessing an extremely weak anal sinus. Further investigations, based on anatomical and/or radular characters, will probably show that M. ektonos belongs to an undescribed genus, but for now attribution to the genus Mioawateria , taken in a broad sense, can be retained.

Etymology: Greek tonos (tune) and prefix ek - (out of), alluding to the peculiar morphological features of this species that are not in harmony with those of its congeners.