Cerithiopsis pisinna, Pimenta & Faria & Figueira & Fernandes, 2024

Pimenta, Alexandre Dias, Faria, Raquel Garofalo De Souza, Figueira, Raquel Medeiros Andrade & Fernandes, Maurício Romulo, 2024, Unraveling another of the ‘ Big Fiveʹ: new species and records of Cerithiopsidae from Brazil (Caenogastropoda: Triphoroidea), Zootaxa 5494 (1), pp. 1-71 : 16-17

Cerithiopsis pisinna sp. nov.

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( Fig. 5 )

Type material. Holotype MNRJ 15391 . Paratype: IBUFRJ 14137 [1], type locality .

Type locality. Brazil, off Espírito Santo State, REVIZEE– Central sta. C1–VV38 (19°28ʹ26ʺS, 38°22ʹ30ʺW, 71 m) .

Etymology. From the Latin word pisinnus = small, little. The species is named for its very small-sized shell and protoconch; also, an allusion to its rarity, currently known by two shells only.

Diagnosis. Protoconch quite small in relation to the shell; area above suture forming a deeply depressed concave region; outer lip strongly crenulated, forming deep channels in inner surface of aperture.

Description. Shell pupoid, slightly inflated, small, reaching 2.5 mm long, 1.1 mm wide, ratio length/width 2.2– 2.5. Protoconch white, smooth, 329–354 μm long, 202–218 μm wide, quite small when compared to the teleoconch, 3.25 whorls of very convex outline, the first one dome-shaped: transition from protoconch to teleoconch with five sinuous well-defined scars. Teleoconch with up to 4.75 whorls of convex profile; color light brown; suture shallow and indistinct; sculpture formed by three nearly equidistant spiral cords and about 18 orthocline axial ribs on the fourth whorl, with squared interspaces; medium-sized, rounded nodules (occupying 42–47% of body whorl length); protuberant spiral cords and axial ribs, with cords slightly more prominent than ribs; adapical spiral cord located quite close to the suture, abapical cord separated from suture by a deeply depressed region; adapical spiral cord initially smaller, reaching a similar size than other cords in the fourth whorl; nearly smooth subperipheral cord; base concave and possibly incomplete in both shells, although two very thin (almost indistinct) and close spiral cords occur; aperture elliptical, reaching 0.65–0.70 mm long, 0.43–0.45 mm wide, ratio length/width 1.4–1.6; outer lip crenulated due to projections of spiral sculpture of body whorl, which form deep channels in the inner surface of aperture.

Remarks. Cerithiopsis pisinna sp. nov. has a very small and somewhat pupoid shell ( Fig. 5 ) that distinguishes it from the other species from Brazil. The most similar Cerithiopsis species from the Western Atlantic are also small, such as Cerithiopsis portoi Rolán & Espinosa, 1996 and Cerithiopsis fuscoflava Rolán & Espinosa, 1996 , from Cuba, Cerithiopsis krisbergi Rolán & Fernández-Garcés, 2007 , from Florida ( USA), Cerithiopsis vicola Dall & Bartsch, 1911 , from Bermuda, and Cerithiopsis satisnodosa Rolán & Fernández-Garcés, 2010 , from Mexico.

Cerithiopsis vicola has a banded coloured shell, with the adapical spiral cord brown or light orange, similarly to C. io, while in C. pisinna the teleoconch is uniformly light brown ( Fig. 5A ).

Cerithiopsis krisbergi and C. portoi have very short interspaces between the nodules on teleoconch whorls and more pupoid shell shapes. Besides that, the protoconch of C. krisbergi has a spiral cord at the abapical portion of body whorls and the protoconch of C. portoi is considerably wider.

Cerithiopsis fuscoflava has a very short (but wider) protoconch of around two whorls, and median spiral cord of teleoconch slightly more prominent than other cords. Cerithiopsis satisnodosa also has a more inflated protoconch, with a less acuminated apex.

Two species from Guadeloupe are also similar to C. pisinna : Cerithiopsis bouchonorum Cecalupo & Perugia, 2020 and Cerithiopsis cabritensis Cecalupo & Perugia, 2020 , especially regarding the small, whitish protoconch and the broad teleoconch. Cerithiopsis pisinna has a darker teleoconch but whiter protoconch than C. cabritensis . The teleoconch of C. pisinna is darker and more homogeneous (without distinction of color patterns between spiral cords) than C. bouchonorum , and the protoconch of C. bouchonorum seems to be more variable, reaching up to four whorls (according to the description, but it appears to reach nearly five whorls— Cecalupo & Perugia 2020: pl. 3, fig. 2c—vs. 3.25 whorls in C. pisinna ) and with a broad or narrow shape (respectively in the holotype and paratype). Either C. cabritensis and C. bouchonorum do not have sinuous scars in the transition from the protoconch to the teleoconch, as observed in C. pisinna .

Cerithiopsis jeffreysi R. B. Watson, 1885 , from the Northeast Atlantic and Mediterranean, presents a very similar teleoconch sculpture and smooth protoconch if compared to C. pisinna . Their main differences are the cylindrical brown protoconch of C. jeffreysi with around four whorls (van Aartsen et al. 1984; Manousis et al. 2018, 2023, Öztürk et al. 2008), while in C. pisinna it has only three whorls, a less cylindrical shape and the whorls are more convex, besides the five sinuous well-defined scars in the transition from protoconch to teleoconch.

Geographic and bathymetric distribution. Only known from the type locality, in the Tropical Southwestern Atlantic Province (Espírito Santo State), from 71 m.

Figures

FIGURE 5. Cerithiopsis pisinna sp. nov. A: holotype, from Espírito Santo State (MNRJ 15391); B–D: paratype, from type locality (IBUFRJ 14137); C–D: body whorl and protoconch of paratype. Lengths of whole shells: A: 2.6 mm; B: 2.5 mm. Scale bars: A–B: 1 mm; C–D: 200 µm.