Buccinoidea, Rafinesque, 1815

Superfamily Buccinoidea View in CoL Family Nassariidae

Genus Phrontis H. & A. Adams, 1853

Phrontis rocas Simone & Abbate , new species ( Fig. 17 View Figure 17 ) https://zoobank.org/ C18E0627-850C-4C55-9021-B2D72F09A068

Types: Holotype MZSP 166666 View Materials , shell . Paratypes: MZSP 166673, 2 shells,MZSP 62443,14 shells from type locality.

Type locality: BRAZIL. Rio Grande do Norte ; Atol das Rocas, 03°51′28.05″S 33°47′58.9″W, 1 m [E.C. Rios leg., L.J. Barcellos col., i.1982].

Diagnosis: Species from Atol das Rocas with shell of relatively large size, walls thick. Color whitish to light beige, monochromatic. Protoconch blunt, of ~2 smooth whorls. Teleoconch whorls shouldered; sculptured by uniform, tall, narrow axial threads, and numerous narrow spiral cords, located close from each other. Aperture slightly shorter than spire. Peristome thick deflected; outer lip with inner liration; callus folded, but restricted to peristome; with large spiral superior fold.

Description: Shell of ~ 11 mm, fusiform, walls thick. Color monochromatic, whitish to light beige. Weakly elongated, ~1.5-1.7× longer than wide. Protoconch mamillated, blunt, of ~2 smooth, rounded whorls ( Fig. 17D View Figure 17 ); width ~ 1.4 mm; transition with teleoconch unclear. Teleoconch of 5-6 whorls, each whorl highly convex, bluntly shouldered; sculptured by uniformly distributed, tall, narrow axial threads, ~ 13 in penultimate whorl; also numerous narrow spiral cords, located close from each other, from suture to suture, covering interspaces between axial threads and part of threads ( Fig. 17 View Figure 17 F-G, H-I), or entire surface ( Fig. 17 View Figure 17 A-C, J-K); interspaces between spiral cords equivalent to ⅓ their width ( Fig. 17 View Figure 17 A-C) of slightly more spaced ( Fig. 17 View Figure 17 F-G), ~ 12 in penultimate whorl. Sculpture of last whorl similar to preceding whorls, with axial threads and spiral cords reaching deep peripheric siphonal sulcus; peristomal thread similar to preceding threads, but clearly larger. Peristome white, thick, rounded; occupying ~45% of shell length, ~55% of shell width ( Fig. 17A, E, F, H, J View Figure 17 ). Outer lip rounded, thick. Anal notch clear, narrow; remaining inner surface with 12-13 spiral liration, with longitudinal, well-spaced, narrow folds, ending at some distance from lip edge. Inner lip as rounded, concave, uniform callus, ventral edge slightly elevated, but extending little beyond peristome area; large spiral superior fold flanking anal notch ( Fig. 17E View Figure 17 ). ending at some distance from callus edge; remaining callus smooth or with low transverse undulations. Siphonal canal short, curved, protruding in right side of anterior half of inner lip, flanked externally by siphonal sulcus; canal narrow, slightly opened and expanded anteriorly. Umbilicus only formed by umbilical sulcus.

Etymology: The specific epithet is derived from the name of its place of occurrence: Atol das Rocas.

Distribution: Endemic from Atol das Rocas.

Habitat: In tide pools up to few m depth, all collected shells with pagurus.

Measurements (in mm): Holotype ( Fig. 17 View Figure 17 A-E): 10.5 by 7.2. Paratypes: MZSP 166673#1 ( Fig. 17 View Figure 17 F-G): 10.6 by 6.3; #2 ( Fig. 17 View Figure 17 H-I): 11.6 by 7.5; MZSP 62443#1 ( Fig. 17 View Figure 17 J-K): 12.1 by 8.0.

Additional material examined: BRAZIL. Rio Grande do Norte; Atol das Rocas, 03°52′S 33°48′W, MZSP 62446 View Materials , 5 View Materials shells ( Equipe MORG col., ii.1977), MZSP 49158 View Materials , 5 View Materials shells (N. Menezes col., ii.1972), MZSP 81785 View Materials , 14 View Materials shells (Simone col., i.1995), Cemitério Pool, 03°51′48.24″S 33°48′50.92″W, MZSP 146887 View Materials , 2 View Materials shells (H. Galvão Fo. col., 10.x.2014), Podes Crer pool, 03°52′20.3″S 33°48′45.82″W, MZSP 146879 View Materials , 1 View Materials shell (H. Galvão Fo. col., 13.ix.2014) GoogleMaps .

Remarks: Phrontis rocas , coauthored by Daniel Abbate, MZSP, clearly belongs to the"complex Nassarius albus ", as such it has been identified so far. Nassarius albus nowadays Phrontis alba (Say, 1826) ( Galindo et al., 2016; MolluscaBase, 2024) is the main issue of a project that has proven to represent a set of several species with similar characterized shells. The set of shell characters reported in the above diagnosis of P. rocas has been shown to be exclusive of that population, being easy to be convincing of being a different entity. The relatively large size, thick walls, and the shell sculpture, with narrow spiral cords covering entirely the shell surface, including the uniform axial threads; the shouldered whorls; and the obese outline, are a set of features that makes easily to recognize it from any other congeners. The coastal populations usually have shells of smaller size, not shouldered, and the spiral cords are more spaced.