Crepidula carioca, Simone, 2006

Simone, Luiz Ricardo L., 2006, Morphological and phylogenetic study of the Western Atlantic Crepidula plana complex (Caenogastropoda, Calyptraeidae), with description of three new species from Brazil, Zootaxa 1112 (1), pp. 1-64 : 26-28

Crepidula carioca new species

(Figs. 22–25, 33, 107–110)

Crepidula protea: Rios 1994: 71 (part).

Types: Holotype: MNRJ 7464 , ♀. From type locality.

Paratypes: BRAZIL. Rio de Janeiro; ANSP 19462 , 1 shell (ex­Smithsonian, USEE); Casemiro de Abreu , Rio das Ostras, Joana beach , MNRJ 9517 , 5 specimens (A. Coelho col. ii/1971) ; Búzios, Raza beach, MNRJ 9516 , 1 shell (L.R. Tostes & A. Coelho col., xii/ 1974) ; Cabo Frio, Arraial do Cabo , MNRJ 3366 , 4 shells (H.S. Lopes col., iii/1950) , Forno Beach, MNRJ 2337 , 2♀ (A. Coelho & S. Ypiranga col., i/1960) , Prainha, MZSP 42053 , 10♀ (Simone & Costa col., 18/iii/2003) ; Niterói, Boa Viagem beach, MNRJ 5480 , 1 shell (H.S. Lopes col.) , MNRJ 7464 , 18♀ (H. Travassos & H.S. Lopes col., 9/iii/1953) , Itaipu beach, MNRJ 2336 , 1 ♂, 4♀ (A. Coelho col., 1959) , MZSP 28737 , 1♀ (Simone col., 12/

vii/1997); Rio de Janeiro, off Santana Island , 22º30'S – 41º23'W 22º43'S – 41º40'W, 48 m depth, MNRJ 9518 (B. Prazeres & O. Silva col. 15–25/x/1963) .

Type locality: BRAZIL; Rio de Janeiro; Niterói, Boa Viagem beach, 22°56'S 43°12'W .

Diagnosis: Shell occurring intertidal in Rio de Janeiro coast. Shell whitish, with periostracum persistent covering most of shell. Siphonal pallial fold low and narrow. Pericardium constricted in middle portion, being narrow in its posterior half. Osphradium occupying about 15% of pallial aperture, bearing about 20 filaments close from each other. Pallial oviduct with 5 seminal receptacles connected to albumen gland almost in same region. Female genital papilla with a pair of folds in posterior side, disappearing at some distance from pore; papilla tip pointed.

Description: Shell (Figs. 22–25): Of medium size (up to 20 mm), white, convex, flat, surface opaque. Protoconch eroded. Periostracum heavy, rich in hair, color pale brown, lost in older regions but generally covering most of shell. Sculpture lacking, except shallow concentric undulations and growth lines. Septum somewhat short, wide, triangular, curved septum lateral insertions slightly far from shell outer edges, mainly at right. Septum anterior edge with a wide central notch, its right edge almost straight, its left edge curved, convex; another narrower notch in left end weakly deeper. Inner surface glossy, white, smooth.

Head­foot (Fig. 108): Similar features to those of C. pyguaia , tentacles more clearly bifurcated, having a somewhat deep furrow at tip.

Mantle organs (Fig. 107): Characters closely similar to those of preceding species. Remarkable features following. Pallial cavity length of larger specimens about 90% of total animal length. Siphonal fold at mantle border shorter and narrower, its right end low, fused with remaining mantle edge. Osphradium with about 20 filaments; length about 15% of pallial cavity aperture; each filament slightly cylindrical, close with each other. Endostyle posterior half running separated from ctenidial vein, running along mantle surface adjacent to it, slightly ventral to ctenidial vein up to gill end.

Visceral mass and circulatory­excretory systems: Same characters than those of C. pyguaia , including sudden narrowing in its left half.

Digestive system: Morphological attributes similar to those of C. pyguaia . Radula (Fig. 33) also similar, except by rachidian slightly narrower, having two pairs of secondary cusps; marginal with seven cusps, second cusp larger and terminally disposed; marginal teeth with six secondary cusps in sub­terminal inner edge.

Genital system: Male (Figs. 108, 109): General features similar to those of preceding Crepidula . Remarkable characters following. Testis whitish, located in anterior region of ventral branch of visceral mass, additionally extending towards posterior along its left side, this region forming successive and decreasing digitiform acina. Seminal vesicle slightly small, bearing 3–4 whorls, narrowing gradually. Penis somewhat long, terminal papilla slender and long, with about half of remaining penis length (Fig. 108).

Female (Fig. 110): General organization similar to those of preceding species. Remarks following. Albumen gland narrow and short. Seminal receptacles rounded, number of 5 decreasing towards anterior; ducts very narrow, connected to albumen gland anterior­right side almost in same region. Capsule gland narrow. Vaginal tube broad and long. Internally low longitudinal, narrow folds. Genital papilla tall, with a pair of longitudinal folds running at some distance from each other along posterior surface, finishing at some distance from pore. Papilla tip somewhat pointed. Genital pore a narrow, sub­terminal slit. Anus in basal level of pallial oviduct.

Measurements (in mm): MNRJ 7464> ♀: 34.0 by 23.5; <♀: 11.0 by 9.0;> ♂: 15.0 by 9.7; ♂ 3: 12.9 by 10.0; ♂ 4: 22.7 by 17.4.

Distribution: Known for coast of Rio de Janeiro.

Habitat: Intertidal rocks up to 48 m depth.

Etymology: The specific epithet refers to the geographic occurrence of the species, i.e., the region of the Rio de Janeiro. The people from the city of Rio de Janeiro are known as “carioca”.

Material examined: Types.

Discussion: Crepidula carioca is closely similar to C. pyguaia , both, in conchological and anatomical features. In the shell they are almost indistinguishable. Crepidula carioca normally has less periostracum, but this feature disappears in dead samples. The number and type of anatomical character, most explored above, based the specific separation of C. carioca from C. pyguaia . The considered more important are: 1) the longer osphradium (about 15% of pallial cavity aperture in C. carioca , wile C. pyguaia has about 5%); 2) osphradium bearing more filaments (about 20 in C. carioca and about 10 in C. pyguaia in larger specimens of equivalent size); 3) fewer seminal receptacles (5, while C. pyguaia has 7); 4) anus closer to pallial oviduct; 5) female genital papilla with different fashion, having a pair of longitudinal papillae in posterior surface and a pointed tip. Crepidula pyguaia and C. carioca are close related species, but they are apparently separated geographically, since no Crepidula of similar feature occur in São Paulo coast, as I have consulted in all local collections.

Crepidula pyguaia and C. carioca differ from the other congeneric species in having a persistent periostracum, whitish shell color, and in occurring in shallow waters (intertidal), these characters can easily and quickly identify any sample. But for differentiating both only based on shell samples it is necessary taking into consideration the locality.