Episcynia itanhura, Simone, Luiz Ricardo L., 2012

Simone, Luiz Ricardo L., 2012, Two new species of Tornidae (Caenogastropoda, Rissooidea) from Espirito Santo, Brazil, ZooKeys 238, pp. 77-85 : 80-82

Episcynia itanhura sp. n. Figs 16-27

Episcinia inornata : Rios 1994: 59 (fig. 221), 2009: 101 (fig. 245) (non d’Orbigny, 1842).

Episcinia inornata form “multicarinata”: Rubio et al. 2011: 126 (fig. 68D) (non Dall, 1889).

Types.

Holotype MZSP 106553 (Figs 16-18). Paratypes: 106556, 18 shells, MNRJ, 3 shells, USNM, 3 shells, all from type locality.

Type locality.

BRAZIL. Espírito Santo; São Mateus, Guriri, 18°47'S, 32°39'W, 3 m depth.

Diagnosis. Shell relatively trochoid. Periostracum with 3 series of peripheral fringes constituted of irregular rods. Surface smooth except for peripheral line of pustules. Peripheral carina wanting (profile rounded).

Description.

Shell. Up to ~2.5 mm, discoid (Figs 18, 24) to trochiform (Figs 20, 25); height ~57-68% of maximum width (Figs 18, 20, 24, 25). Color white, weakly translucent (Figs 16-20). Protoconch of 1 whorl, ~90 µm, weakly-turbiform (Figs 26, 27); whorl of rounded profile, suture shallow; surface glossy, smooth; occupying ~7% of shell size; located almost central, weakly dislocated towards right (Fig. 17). Transition protoconch-teleoconch clear, orthocline (Figs 26, 27). Spire dome-shaped to elevated, with ~66% of shell width; ~60-64% of shell height. Te leoconch up to 4 whorls, uniformly growing inferiorly; last whorl with rounded profile, lacking peripheral carina. Sculpture practically absent, except for growth lines looking undulations and aligned set of small pustules located just superiorly to suture and in middle level of past whorl periphery; each pustule rounded, separated from neighboring pustules by space equivalent to half its width; 2 to 4 equidistant, very weak spiral cords present in ~50% of specimens located in superior region of each whorl (Figs 20, 25); inferior region of body whorl only with growth lines (Figs 19, 22). Umbilicum widely opened; maximum diameter ~30% shell width; flanking by strong, somewhat planar slope, beating only growth lines; weak angulation marking periphery of umbilicum (Figs 19, 23, 24, 25). Aperture slightly prosocline (Figs 21, 22, 23); elliptical (longer axis vertical) (Figs 24, 25); with ~36% shell width, ~40-43% of shell height. Callus practically absent, weakly covering adjacent whorl in apertural implantation (Figs 21, 23).

Periostracum (Figs 16-18). Opaque, transparent, color yellowish beige (Figs 16-18). Three series of rods running on periphery (Fig. 18); central fringe running on pustule lines; other 2 fringes running above and below central fringe, distance between fringes equivalent to ~1/3 of whorl height; periostracum rods located on fringes not uniformly distributed and sized; longer rods extending ~10% shell width, weakly coiled, distantly separated from neighbor rods.

Measurements (in mm). Holotype (Fig. 18): 2.0 by 1.1; paratypes MZSP 106556 (Fig. 20)#1: 2.2 by 1.3; (Fig. 24)#5: 2.6 by 1.5; (Fig. 25)#4: 2.5 by 1.6.

Distribution.

Brazil, from Bahia to São Paulo.

Habitat.

Sandy bottoms, ~3 m depth (no living specimens collected).

Material examined.

Types. Additional material: MZSP 106571, 90 shells from type locality. BRAZIL. Bahia; Salvador, Itapoã beach, MZSP 53439, 1 shell (C.M. Cunha col.). Rio de Janeiro; Cabo Frio, MZSP 57159, 2 shells (17/ii/1970). São Paulo; off Ubatuba, MZSP 88431, 1 shell (Veliger II, sta. PI-15; 21/i/1986); 23°33'978"S, 45°09'821"W, 12.3 m depth, MZSP 42087, 1 shell (Biota sta. 145i; 16/iv/2002). N.B. These samples are not part of the type material because of low quality of the shell preservation.

Etymology.

The specific epithet is derived from the Paritintin word Itanhura’mbi - chain used as necklace ( Betts 1981), an allusion to the peripheral ornamentation of the shell.

Discussion.

Episcynia itanhura is similar to Episcynia inornata ( d’Orbigny, 1842), from Florida and Caribbean, differing in lacking so developed peripheral carina, the profile of each whorl is rounded while that of Episcynia inornata is bluntly pointed ( Rubio et al. 2011, Figs 68B, 69); Episcynia itanhura has a more developed axial undulation, almost sculpture (e.g., Figs 20, 25), this is rare in Episcynia inornata , in such the surface is smoother and glossy. The size of the protoconch of Episcynia inornata has been referred as 190 µm ( Rubio et al. 2011), while that of Episcynia itanhura is about half that size (~90 µm, Figs 26, 27). The periostracum rods are organized in 3 fringes in Episcynia itanhura (Fig. 18), while a single pair is found in Episcynia inornata ( Andrews 1971: 68; Abbott 1974: 86). The 3 fringes are also found in Episcynia multicarinata ( Dall 1889), from North Carolina to north Caribbean, Episcynia itanhura differs in having periostracum rods more sparsely and less uniformly developed, by the deeper suture, and by the straighter profile of spire. The differences between Caribbean and Brazilian specimens have been pointed in literature ( Rubio et al. 2011, fig. 68D), however, the differences obviously did not influenced the specific separation. Nevertheless, some doubt still remains in relation to the specimen figures in that paper ( Rubio et al. 2011), because that illustrated specimen has whorls with almost squared profile, possibly it belong to another undescribed specimen. No specimen with such features has been examined herein. Additionally, there is some uncertainties respect to the possible synonymy between Episcynia inornata and Episcynia multicarinata ( Dall 1889), described from North Carolina. Dall (1889: 392-393) clearly stated a specimen with four to five carinas per whorl. This feature is not found in Episcynia inornata or allied species; this can demonstrate a valid entity. Moreover, Dall still described a more richness of sculpture, a lack of periostracal fringe in peripheral carina, and color yellow, whose can be extra indicative of specific differentiation. Despite further studies are necessary to clarify the question, Episcynia itanhura cannot be confused with Episcynia multicarinata .