Cerithiopsis vescula, 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 : 35-37

Cerithiopsis vescula sp. nov.

urn:lsid:zoobank.org:act:55D10F81-6393-41F3-9B8F-E37A3ABA5408

( Fig. 17 )

Type material. Holotype: IBUFRJ 12907 . Paratypes: Brazil: -- Rio de Janeiro state: 23°04ʹ14ʺS, 40°59ʹ31ʺW, 100 m, 17/xii/2004: MNRJ 33012 [1*p]; HAB 16 sta. G3: MNRJ 16529 [1*p].

Type locality: Brazil, off Bahia state, Baía de Todos os Santos; O. Falcão coll. ; 1997.

Etymology. From the Latin word vesculus = weak, poor, thin, little. This species is named after its weak adapical spiral cord in the first teleoconch whorls.

Diagnosis. Protoconch conical with first whorl smooth, remainder whorls with a spiral cord close to suture; teleoconch whorls with the adapical spiral cord very weak and close to the median cord, but not fusioned, becoming more separated on subsequent whorls.

Description. Shell slightly pupoid, up to 2.8 mm long, 1.0 mm wide. Protoconch white, conical, 380 μm long, 240 μm wide, with 4.0 convex whorls; embryonic shell dome-shaped, smooth; larval shell with a smooth spiral cord close to abapical suture. Teleoconch with up to seven whorls of slightly convex outline; color dark brownish; sculpture formed by three spiral cords and around 18 orthocline axial ribs on the body whorl; squarish to rounded large-sized nodules; adapical spiral cord of early teleoconch with very small nodules very close to median cord, but clearly separated from it; nodes of adapical spiral cord enlarge during shell growth and become of equal size of median spiral cords on body whorl; distance between adapical and median rows enlarge along shell growth, distance to abapical row around twice nodule size; spiral cords almost equidistant on body whorl. Suture somewhat channeled. Subperipheral cord smooth; base with a median smooth basal cord, abapical region with very fine spiral striae; aperture rhomboid, around 0.6 mm long, 0.3 mm wide; short and open anterior canal, acute posterior sinus; inner lip somewhat projected over the parietal wall.

Remarks. Figueira & Pimenta (2008) listed several shells of C. fusiformis from the eastern Brazilian coast. Their figure 4 (herein illustrated in Fig. 17C, G ) belongs to Cerithiopsis vescula sp. nov.; it has a very similar shell shape and its protoconch is identical to that of C. fusiformis ( Fig. 16D–E ), but the teleoconch sculpture is distinct. The two adapical spiral cords do not show the fused aspect of a bilobed nodule as in C. fusiformis ; the adapical cord is much weaker in early teleoconch whorls and distinctly separated from the median cord ( Fig. 17A–B ). Along the teleoconch whorls, the adapical cord becomes more pronounced, reaching the same size as other cords in the body whorl ( Fig. 17B–E ).

Cerithiopsis vescula is also similar to C. aimen ( Fig. 20A – D ). The distinction between them relies mainly on the first teleoconch whorl, in which the median spiral cord is the weakest in C. aimen ( Fig. 20C ), while in C. vescula the adapical one is always the weakest ( Fig. 17F – G ).

Cerithiopsis nimia ( Fig. 8 ) presents a similar teleoconch sculpture, in which the adapical spiral cord is less pronounced on early teleoconch whorls whorls, and it is somewhat adhered to the median cord, but not fused. However, in C. nimia this adapical cord is much more detached from the median one, and the shell shape is more elongate.

Geographic and bathymetric distribution. Tropical Southwestern Atlantic Province , from Bahia to Rio de Janeiro states. 76 m to 100 m.

Figures

FIGURE 8. Cerithiopsis nimia sp. nov. A: holotype, from Rio de Janeiro state (MNRJ 30000). B–J: paratypes from Rio de Janeiro state (B: MNRJ 31361; C–G, I: MNRJ 16261; H, J: MNRJ 16253); E: detail of teleoconch sculpture of shell in D; F: body whorl of shell in D; G–I: protoconch and detail of shell in D; H–J: protoconch and detail. Lengths of whole shells: A–B: 2.8 mm; C: 2.7 mm; D: 2.8 mm. Scale bars: A–D: 1 mm; E: 500 μm; F: 200 μm; G–H: 100 μm; I–J: 50 μm.

FIGURE 16. Cerithiopsis fusiformis (C. B. Adams, 1850). A: holotype from Jamaica (MCZ 186127); B, D, F: shell from Rio de Janeiro state (IBUFRJ 13665); C, E, G: shell from Bahia state IBUFRJ 12906); A–C: whole shell; D–E: protoconchs of shells in B and C, respectively; F: detail of teleoconch sculpture of shell in B; G: body whorl of shell in C. Lengths of whole shells: A: 2.6 mm; B: 2.8 mm; C: 2.8 mm. Scale bars: A–C: 1 mm; D–F: 100 µm; G: 200 µm.

FIGURE 17. Cerithiopsis vescula sp. nov. A–B, D–F: paratypes from Rio de Janeiro state (A: MNRJ 33012; B, D–F: MNRJ 16529); C, G: holotype, from Bahia state (IBUFRJ 12907); D: detail of teleoconch sculpture and body whorl of shell in B; F–G: protoconchs of shells in B and C, respectively. Lengths of whole shells: A: 2.7 mm; B: 2.8 mm; C: 2.1 mm. Scale bars: A–C: 1 mm; D–G: 100 µm.

FIGURE 20A–D. Cerithiopsis aimen Rolán & Espinosa, 1996. Shell from Rio de Janeiro state (MNRJ 16531). FIGURE 20E–H. Cerithiopsis prieguei Rolán & Espinosa, 1996. Shell from Rio de Janeiro state (MNRJ 32617). FIGURE 20I–L. Cerithiopsis balaustium Figueira & Pimenta, 2008. Shell from Rio de Janeiro state (MNRJ 16527). C, G, K: protoconch of shells in B, F and J, respectively; D: detail of teleoconch whorls of shell in B; H, L: detail of protoconch sculpture of protoconchs in G and K, respectively. Lengths of whole shells: A–B: 1.8 mm; E–F: 2.4 mm; I: 1.8 mm; J: 1.7 mm. Scale bars: A–B, E–F, I–J: 1 mm; C–D, G–H, K–L: 100 µm.