Pinna nembia, Simone, 2024

Pinna nembia View in CoL new species

( Fig. 53 View Figure 53 ) https://zoobank.org/ EE5017D1-5B54-4114-B247-C93BBF8FE602

Types: Holotype MZSP 102181 View Materials , specimen . Paratypes: MZSP 165698 View Materials , 2 View Materials spm from type locality. BRAZIL. São Paulo ; Ilhabela, Ilha dos BÚzios, Costa do Aquário , 23°47.762′S 45°9.282′W, 10 m, MZSP 105570 View Materials , 1 View Materials spm (Simone et al. col., 16.v.2012) GoogleMaps .

Type locality: BRAZIL. São Paulo ; São Sebastião, Ilha dos Alcatrazes, Saco da Tartaruga , 24°06′24.95″S 45°42′17.19″S, 17 m (Simone et al. col., 05.x.2011) .

Diagnosis: SE Brazilian species, with adult up to ~ 250 mm; color light beige-translucent. Umbonal angle ~40°. Sculpture ~10 radial wide folds, relatively uniform, each one entirely wide, usually rich in scales.

Description: Shell up to ~ 250 mm. Basic color light beige-translucent. Antero-posteriorly long, 2.4-2.1 times longer than heigh; flattened, ~6 times longer than wide. Middle blunt longitudinal weakly carina developed, more pronounced in anterior third ( Fig. 53A, C, E, F, H, I View Figure 53 ). Sculpture growth lines, with weak concentric undulations in more posterior regions; sparse scales in posterior half ( Fig. 53G View Figure 53 ); ~10 radial (longitudinal) folds, all of them appearing uniform undulations since anterior beak, increasing like that up to posterior margin, sometimes in straight manner ( Fig. 53C, E View Figure 53 ), sometimes with weak undulations, mainly posterior ( Fig. 53F, H, I View Figure 53 ). Dorsal edge practically straight ( Fig. 53E, F View Figure 53 ) or with weak posterior curve ( Fig. 53 View Figure 53 A-D, H-I); ventral edge straight ( Fig. 53 View Figure 53 E-I) to sightly convex ( Fig. 53 View Figure 53 A-D); posterior edge amply rounded ( Fig. 53 View Figure 53 H-I) to weakly flattened ( Fig. 53 View Figure 53 A-F). Hinge edentulous, with ligament all along it, from anterior beak, up to short region posterior to posterior edge. Posterior region and posterior quarter of ventral region with opened gap ( Fig. 53G View Figure 53 ). Inner surface glossy, with pair of iridescent regions in anterior third, separated by narrow longitudinal opaque band ( Fig. 53B, D View Figure 53 ); muscular scars not clear.

Etymology: The specific epithet is a Latinization of the native Guarani word ñemby, meaning "south," in allusion to the southern occurrence of the species. It is the southernmost species of the genus in the Western Atlantic.

Distribution: Coasts of Rio de Janeiro to São Paulo.