Setia netoae 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

Taxon classification Animalia Littorinimorpha Rissoidae

Setia netoae Avila & Cordeiro sp. n. Figure 3

Type material.

Holotype, DBUA 745 (1 spc., 1.57 × 0.90 mm); paratype 1, DBUA 1086 (1 spc., 1.55 × 0.89 mm), São Miguel Island ( Baía de Rosto do Cão, low intertidal, 07/1990); paratype 2, DBUA 1087 (1 spc., 1.15 × 0.70 mm); paratype 3, DBUA 1088 (1 spc., 1.17 × 0.71 mm), São Miguel Island ( Baía de Belém, São Roque, 8.6 m depth, 04/07/1990); paratype 4, DBUA 1089 (spc., 1.26 × 0.74 mm); paratype 5, DBUA 1090 (spc., 1.12 × 0.68 mm), paratype 6, DBUA 1091 (spc., 1.36 × 0.79 mm), Graciosa Island ( Baía da Folga, 8 m depth, 10/06/1988); paratype 7, DBUA 264 (1 sh., 2.09 × 1.07 mm), Flores Island (Lajes das Flores, 6-10 m depth, 27/10/1990).

Type locality.

Baía de Rosto do Cão, São Miguel Island, Azores.

Etymology.

Named after Ana Neto, an Azorean marine phycologist from the University of the Azores.

Description.

Shell minute, cream to translucent in colour, oval-high conical, up to 2.1 × 1.1 mm (Fig. 3 A–D and F). Protoconch dome-shaped (typical of the genus), smooth, whorls 1.25, diameter 250 µm, separated from the teleoconch by a clearly visible line (Fig. 3G). Teleoconch with 3.5 to 4 inflated, rounded, strongly convex whorls sculptured with weak axial growth lines; whorls with regular contour and conspicuous increase in width (Fig. 3 A–F). Spire moderately high. Suture deep, constricted (Fig. 3E). Last whorl large, globose, 60% of shell length (Fig. 3 A–F). Base large, rounded (Fig. 3E). Aperture oval, oblique with continuous and simple peristome (smooth within), and posterior angulation (Fig. 3E). Parietal region thin, rather straight (Fig. 3E). Outer and inner lip with a thin edge (not thickened) (Fig. 3E). Umbilicus a very narrow fissure (Fig. 3E). Animal bright-yellow, with very distinctive single dark-brown patch to inner side of head, readily visible at transparency (Fig. 3 A–C and F). Operculum simple, thin, nucleus eccentric, yellowish at transparency (Fig. 3A, B and F).

Habitat.

On rocky shores covered by algae, from the intertidal down to 10 m depth.

Geographical distribution.

Flores, Graciosa and São Miguel Islands. Probably endemic to the Azores.

Remarks.

This species appears to be uncommon on the Azorean shores. It differs from Setia subvaricosa by lacking the vertical reddish flames on the shell that characterizes this species. It further differs from Setia subvaricosa by the thinner outer lip of the aperture and by the absence of spiral threads on the protoconch. Setia netoae sp. n. differs from Setia alexandrae sp. n. in having a more slender shell, 4 instead of 3 whorls on the teleoconch, by the distinctive colour pattern of the animal, and by the proportions of the last whorl/total length of the shell, which are 60% versus 70-75%, respectively. Setia netoae sp. n. differs from other Atlantic congeners (cf. Ávila et al. 2012; and present study) by lacking the usual colourful patterns, such as wavy flames, blotches and lines, observed in the shells of this genus. It also has a more elongate shell than most of the known Setia . The shell resembles that of similar sized Setia antipolitana (van der Linden & Wagner, 1987), but the latter has vertical lines interrupted medially that are not present in Setia netoae sp. n.