Crepidula depressa Say, 1822

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 : 19-21

Crepidula depressa Say, 1822

(Figs. 5, 6, 32, 83–96)

Crepidula depressa: Collin 2000: 1500–1512 (figs. 1, 2, 3C–D, 4, 5B, E, 6center); 2001 (fig. 5).

Neotype: ANSP 19187 ; UNITED STATES OF AMERICA; Florida , Sanibel Island, Sanibel Marina, 26º27'N 82º02'W.

Differential diagnosis: Shell (Figs. 5, 6): growth lines stronger, producing a rougher outer surface. Color entirely white. Anterior edge of septum with a deeper notch in left side. Other details in Collin (2000).

Head­foot (Figs. 84, 89, 91): Tentacles tip simple. Eyes dark, very small, located on very short ommatophores in level between basal and middle thirds of tentacles lateral margin. Head and neck with about same foot length. Columellar muscle reduced, contours anterior border of shell septum, more concentrated at right (Fig. 84). Anterior edge of foot, with pedal gland furrow, presenting projected edges in both sides.

Mantle organs (Figs. 83, 85–88): Mantle border special arrangement of folds in middle region of pallial cavity aperture with very broad main fold, located from gill anterior end running towards left, decreasing gradually (Figs. 87, 88); both edges of this fold unite at level of osphradium by a short distance, and connect to mantle border. This fold possesses a broad and shallow central furrow. Dorsal shell muscle well developed (Fig. 83: dm), relatively large. Lateral shell muscle (Figs. 83: lm) very small, almost absent. Pallial cavity aperture occupies about 2/3 of anterior half of shell border turned to right (if shell compared with a clock, in dorsal view and with head occupying 12 oclock, pallial aperture begins in 9:30 and finishes in 3 oclock) (Fig. 86). Pallial cavity length about same of total length of animal (Figs. 83, 87). Osphradium very small, length about 1/ 10 of pallial aperture length. Osphradium leaflets rounded, slightly far from each other, somewhat thick and tall, varying around 8 in number (Fig. 88). Gill filaments triangular base somewhat longer, extending by about half of filament length, but narrower than that of C. atrasolea . Endostyle (Figs. 87, 88: en) divided along its length by a narrow, middle furrow, into 2 similar ridges. Hypobranchial gland very thin.

Visceral mass (Figs. 83, 93): relatively shorter.

Circulatory and excretory systems (Figs. 87): renal lobe slightly thicker attached to intestine.

Digestive system (Figs. 89, 90, 92): Buccal mass occupying most of proboscis inner space and a short portion of haemocoel posterior to it. Pair of dorsal folds somewhat notched (Fig. 90) and narrow. Odontophore muscles: m7 pair with insertion inside radular sac strongly connected with each other; m11 pair also present; m14, very narrow, almost filiform. Radula extending little beyond odontophore length. Radula (Fig. 32): rachidian tooth with 3–4 secondary cusps; lateral tooth with about 12 triangular cusps, forth cusp very larger; inner marginal tooth with about 8 cusps along its inner­subapical margin and 4 in along its outer subapical margin; inner marginal tooth with about 3 small and pointed cusps long its inner subapical margin. Salivary glands very narrow (Figs. 89), length little longer that half of haemocoel length. Salivary glands aperture an oblique slit in anterior region of dorsal folds of buccal mass (Fig. 90). Esophagus (Figs. 89, 92) very narrow, long. Stomach (Fig. 92) very similar to that of C. atrasolea , except for anterior and posterior ducts to digestive gland dichotomic at their base, practically double. Digestive gland greenish beige in color. Intestine very similar in attributes to that of C. atrasolea (Fig. 92).

Genital system: Development: See Collin (2000).

Male (Figs. 91, 93): Testis cream in color, located in anterior and left regions of visceral mass. Seminal vesicle proportionally larger, highly convoluted, narrow, cream in color, located in anterior­right extremity of visceral mass. Penis large (about 5 times tentacle length, and about 3 times its width), curved; narrowing gradually towards tip, lacking a clear separation with terminal papilla. Penis furrow runs in middle region of penis ventral surface until papilla tip.

Female (Figs. 95, 96): Ovary pale yellow in color. Albumen gland narrower. About 4 seminal receptacles inserted in right side of albumen gland, successively larger towards anterior. Seminal receptacles duct narrow and long. Capsule gland narrower, inner duct narrow, flat, straight. Vaginal tube originating from left region of capsule gland; running parallel to capsule gland towards right; form very thick and broad (little slender than capsule gland width); length about same as that of capsule gland; vaginal tube inner surface with 7–8 longitudinal, irregular folds, starting just in region after capsule gland. Genital papilla very tall, situated close to anterior region of albumen gland (part covering it), at some distance from anus; its inner surface with vaginal tube folds converging and becoming only 3 broad longitudinal folds. Papilla with about 5 longitudinal folds along posterior and left surfaces, starting gradually in papilla base, finishing at short distance from pore; those more posterior folds taller, forming a deep furrow between their distal end as genital pore lips. Genital pore a small, transversal, terminal slit.

Central nervous system (Figs. 89, 94): With normal characters as in other described Crepidula ( Simone 2002) , located posterior, far removed from buccal mass, ganglia somewhat concentrated, statocyst with statolith.

Habitat: See Collin (2000), on oyster shells and shells occupied by hermit crabs, 3–5 m depth.

Distribution: Gulf coast of Texas, Gulf and Atlantic coasts of Florida.

Measurements of shells (in mm): MZSP 36326 ♀ 1: 14.1 by 10.5; ♂ 2: 4.8 by 3.6; ♀ 3: 9.7 by 7.2.

Material examined: UNITED STATES OF AMERICA; Florida; Sanibel Marina, MZSP 36326, 10 specimens (R. Collin col.); St. Petersberg , MZSP 35844 , 16 specimens (T. Bert col. 1977, R. Collin leg & id.) .