Manzonia martinsi Avila & Cordeiro

Cordeiro, Ricardo & Avila, Sergio P., 2015, New species of Rissoidae (Mollusca, Gastropoda) from the Archipelago of the Azores (northeast Atlantic) with an updated regional checklist for the family, ZooKeys 480, pp. 1-19 : 6-8

Taxon classification Animalia Littorinimorpha Rissoidae

Manzonia martinsi Avila & Cordeiro sp. n. Figure 4

Type material.

Holotype, DBUA 788 (sh., 1.75 × 1.13 mm); paratype 1, DBUA 1092 (sh., 1.88 × 1.20 mm); paratype 2, DBUA 1093 (sh., 1.76 × 1.14 mm); paratype 3, DBUA 1094 (sh., 1.72 × 1.10 mm); paratype 4, DBUA 1095 (sh., 1.76 × 1.06 mm), São Miguel Island ( São Vicente Ferreira, 4.7 m depth, 16/07/1997).

Type locality.

São Vicente Ferreira, São Miguel Island, Azores.

Etymology.

Named after António M. de Frias Martins, a malacologist from the University of the Azores.

Description.

Shell minute, white, oval-conical, up to 1.9 × 1.2 mm (Fig. 4A). Protoconch paucispiral, clearly demarcated convex whorls 1.25, diameter 340-365 µm; whorls with a pronounced keel adapically (Fig. 4I) and 5-6 faint spiral cords visible on surface between suture and keel (Fig. 4H and I). Teleoconch with 3 to 3.5 inflated, rounded, strongly convex whorls, angulated at a distance abapically from suture (Fig. 4 B–F). Spire moderately high. Suture very deep, strongly constricted (Fig. 4 B–F). Last whorl large, globose, 65% of shell length (Fig. 4 B–D and F). Base large, rounded (Fig. 4 B–D and F). Spiral sculpture consisting of flat cords (5-6 on first teleoconch whorl, 8-9 on penultimate whorl and 9-10 on body whorl) equal to two times broader than the interspaces ornamented with minute pits arranged in spiral lines (Fig. 4G); interspaces with 4 to 6 raised spiral striae (Fig. 4G). Abapical area of body whorl (base) with two strong spiral cords separated by broad spiral depression; third spiral cord located nearer the lip may be present (Fig. 4B and F). Axial sculpture consisting of 10-14 flexuous, opisthocline, moderately broad and strongly elevated ribs (body whorl), fading on base (about 7-8th spiral cord) (Fig. 4B, D and F). Intersection of axial and spiral sculptures raising small knobs (Fig. 4E). Aperture oval, strongly thickened, oblique with continuous peristome (Fig. 4 B–D and F). Parietal region slightly convex (Fig. 4 B–D and F). Outer lip with very thickened edge (smooth inside) (Fig. 4 B–D and F). Inner lip moderately thickened and slightly concave (Fig. 4 B–D and F). Umbilicus lacking (Fig. 4 B–D and F).

Habitat.

In the infralittoral on rocks covered by algae.

Geographical distribution.

São Miguel Island. Probably endemic to the Azores.

Remarks.

Manzonia martinsi sp. n. is similar in shell shape to Manzonia lusitanica Gofas, 2007 and Manzonia crispa (Watson, 1873). It differs from Manzonia lusitanica in having a lower number of spiral cords on the body whorl (9-10 in the new species and 12-13 in Manzonia lusitanica ). Manzonia martinsi sp. n. has 9-10 spiral cords on the body whorl and 4-6 raised spiral striae on the interspaces between cords, while Manzonia crispa has 7 spiral cords on the body whorl and 8-10 lower spiral striae between cords. Manzonia martinsi sp. n. differs from Manzonia arata Gofas, 2007 in the number of raised spiral striae on the interspaces as well as on the number of spiral lines with pits on the spiral cords, which are lower 2 to 3 times in the new species (Table 1).