Holotype MZSP 106551 (Figs 1–5). Paratypes: 106552, 16 shells from type locality.

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

Shell of about 2.5 mm; almost planispiral. Three carina-like spiral threads somewhat equidistant; superior surface smooth or with scanty spiral cords. Periphery smooth except threads. Peri-umbilical area with string spiral cords. Periostracum with aligned series of tall rods on spiral threads.

Shell. Up to ~2.5 mm, discoid; height ~52% of maximum width (Figs 3, 10, 12). Color pure white, weakly translucent (Figs 1, 2, 5, 6). Protoconch of 2 whorls, weakly-turbiform (Figs 4, 10, 11, 15); whorls of rounded profile, suture shallow; surface glossy, smooth; occupying ~10% of shell size; located almost central, weakly dislocated towards right. Transition protoconch-teleoconch unclear (Fig. 15). Spire weakly elevated, with ~45% of shell width; ~15% of shell height. Teleoconch up to 2.5 whorls, uniformly growing weakly planispiral, bearing three somewhat equidistant carinas (Figs 9, 10, 11, 12); peripheral carina as tallest, profile blunt, ~100°, located in middle level of last whorl, inflating ~15% shell width; inferior carina similar to peripheral carina, located midway between this and peri-umbilical slope (Figs 10, 12, 13); superior carina with ~half size as peripheral carina, located midway between this and adjacent suture (Figs 6, 8, 9, 11); between carinas somewhat planar surface, being weakly elevated in carina’s base. Sculpture superior to peripheral carina absent (Figs 11, 14) to series of narrow, low, obsolete spiral cords (Figs 6, 8), varying from zero (surface smooth, Fig. 14) to ~10 (Fig. 8); interspaces between spiral cords ~1/4 their width; sculpture inferior to peripheral carina absent (smooth). Umbilicum widely opened; maximum diameter ~30% shell width; flanking by strong, somewhat planar slope; sculptured from 1 to 5 spiral cords, with interspaces ~3 times their width (Figs 5, 7, 12, 13). Aperture weakly prosocline (Figs 4, 9, 11, 13); rounded, weakly pentangular, i.e., bearing somewhat equidistant blunt angles produced by three carinas and umbilical slope (Figs 10, 12); with ~35% shell width, ~70% of shell height. Callus practically absent, weakly covering adjacent whorl in apertural implantation.

Periostracum (Figs 1–5). Opaque, transparent, color pale beige. Series of tall rods aligned on three carinas; rods of peripheral carina augmenting ~10% shell width (Figs 1, 2), about twice taller than wide, tip rounded, slightly broader than base; rods of superior carina similar to those of peripheral carina, with ~80% of their size (Figs 3, 4); rods of inferior carina also similar to those of peripheral carina, with ~30% their height and ~60% their width (Figs 3, 5). Each rod blade-like, flexible, located close to each other from same carina, forming tall flexible ridge on each carina. Periostracum ridge on three carinas suddenly finishing at apertural level. On aperture, region between ridge of superior carina and insertion of outer lip in adjacent preceding whorl a small region with ridge of peripheral ridge reabsorbed, forming anal notch with ~1/5 of aperture size (Figs 1, 2, 5).

Measurements (in mm). Holotype: 2.8 by 0.9; paratype 106552 (Fig. 10): 1.7 by 0.8.

Only known from type locality.

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

Types.

Cyclostremiscus mohicanus is similar to Cyclostremiscus beauii (Fischer, 1857) (Rosenberg et al. 2009; Rubio et al. 2011) from Florida and Caribbean. It differs by the smoother superior surface, lacking so developed spiral cords, the contrary happens in the umbilicum, in such that of Cyclostremiscus mohicanus has a series of spiral cords, while Cyclostremiscus beauii has only growth lines; the size is also different, as Cyclostremiscus mohicanus has about 3 mm, while Cyclostremiscus beauii reaches 9-10 mm. Cyclostremiscus mohicanus also resembles Cyclostremiscus pentagonus (Gabb, 1873), also from Caribbean, it differs by the more developed spiral sculpture in the superior shell surface, by the peri-umbilical spiral sculpture, in being slightly taller (height/width tax= ~52% against ~48% of Cyclostremiscus pentagonus), and in having the peripheral carina slightly more elevated. Cyclostremiscus pentagonus has been referred as occurring in south Brazil (Rios 2009: 59, in Porto Belo, Santa Catarina; Rubio et al. 2011: 91); as that material was not found, this record is here considered doubtful, but possibly they are of Cyclostremiscus mohicanus. Another important difference between Cyclostremiscus mohicanus and Cyclostremiscus pentagonus is the protoconch, it has ~2 whorls (Fig. 15), while that of Cyclostremiscus pentagonus is ~0.5 whorl longer (Rubio et al. 2011, fig. 46F). Cyclostremiscus mohicanus is also somewhat similar to Cyclostremiscus trilix (Bursh, 1885), sharing the size and the carinas shape; however, it differs from that species in lacking the microtubercles on the protoconch, in having spiral sculpture in surface between suture and superior carina, and in being taller (height/width tax= ~52% against ~42% of Cyclostremiscus trilix).

The periostracum bearing expansions are relatively common in living and fresh-died specimens of tornids. However, a periostracum with the Cyclostremiscus mohicanus arrangement appears to be novelty. Nothing like that has been found in other congeneric species. Cyclostremiscus mohicanus clearly belongs to the “group 1” as defined by Rubio et al. (2011: 84), which encompasses carinate species of the genus, with 2 or 3 peripheral carinas. Possibly all carinas of those species are base of periostracal expansions like those of Cyclostremiscus mohicanus.

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

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. Teleoconch 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.

Brazil, from Bahia to São Paulo.

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

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.

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.

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.