Two new species of Tornidae (Caenogastropoda, Rissooidea) from Espírito Santo, Brazil

Abstract Two new species of shallow water Tornidae are found in Espírito Santo state, Brazil, formally described herein. They belong to a complex group of tiny gastropods, in such the taxonomy is very confused. Cyclostremiscus mohicanus sp. n. is characterized by three well-developed spiral, equidistant carinas, working as base of three series of tall, aligned periostracal rods. Episcinia itanhuna sp. n. has as single sculpture a series of pustules in periphery, but the periostracum bears three series of peripheral fringes with irregular rods. The new species are compared with the allies, showing a close relation with Caribbean fauna, but possessing worthy differences. These similarities have raised misidentifications.


Introduction
The Tornidae Sacco, 1896 has also been called Vitrinellidae Bush, 1897. They normally are tiny (~2 mm), discoid gastropods living in coastal shallow waters, usually associated with other organisms, such as algae, worm galleries, etc.
Possibly because of the minute size, the tornids are normally absent in faunal inventories. In collections, the few samples are normally poorly identified, and the draft identification, at least in Brazilian samples, is normally south expansions of North Atlantic or Caribbean species, resulting exceedingly wide distributed species. The same has reflected in the pertinent literature. This wide distribution contrasts with the minute size and the paucispiral protoconch, both normally indicating short or no planktonic phase, and low dispersion. On the other hand, this supposedly wide distribution does not resist to a close look, in such interesting and important differences appear confronting distant collected samples. This paper is just another example. It deals with two species so far identified as species described from Florida and North Carolina, which has been extended to Caribbean. However, some significant details have demonstrated that the Brazilian samples actually belong to different, undescribed species.
The western Atlantic tornid fauna had an important improvement with a recent revision (Rubio et al. 2011), allowing a better analysis of samples. The genus Cyclostremiscus Pilsbry & Olsson, 1945 (type species, OD, Vitrinella panamensis C.B. Adams, 1852, from Caribbean) has a worldwide, tropical distribution. It is mainly characterized by usually carina-bearing shell, normally with secondary sculpture in intervals of carinas, and a wide, opened umbilicus (Pilsbry and Olsson 1945: 266;Rubio et al. 2011: 83). The genus Episcynia Mörch, 1875 (type species, M, Solarium inornatum d'Orbigny, 1842, from Caribbean), is restricted to Pacific and Atlantic coasts of Americas. It is mainly characterized by serrate peripheral keel, deep umbilicus, and spiral fringes with periostracal filaments (Rubio et al. 2011: 125). This paper deals with the formal descriptions of two species belonging to these genera, recently collected in sediment sorting by local researchers, as well as confrontation with type specimens.

Material and methods
The studied samples are only empty shells in all kinds of preservation levels, since specimens with periostracum to eroded shells. Diagnosis. 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.
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).
beauii has only growth lines; the size is also different, as C. mohicanus has about 3 mm, while C. beauii reaches 9-10 mm. C. mohicanus also resembles C. 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 C. 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 C. mohicanus. Another important difference between C. mohicanus and C. pentagonus is the protoconch, it has ~2 whorls (Fig. 15), while that of C. pentagonus is ~0.5 whorl longer (Rubio et al. 2011, fig . 46F). Cyclostremiscus mohicanus is also somewhat similar to C. 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 C. trilix).
The periostracum bearing expansions are relatively common in living and freshdied 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. C. 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 C. mohicanus.
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).
Periostracum (Figs 16-18). Opaque, transparent, color yellowish beige . 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 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 E. 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 E. inornata is bluntly pointed (Rubio et al. 2011, Figs 68B, 69); E. itanhura has a more developed axial undulation, almost sculpture (e.g., Figs 20, 25), this is rare in E. inornata, in such the surface is smoother and glossy. The size of the protoconch of E. inornata has been referred as 190 µm (Rubio et al. 2011), while that of E. itanhura is about half that size (~90 µm,Figs 26,27). The periostracum rods are organized in 3 fringes in E. itanhura (Fig. 18), while a single pair is found in E. inornata (Andrews 1971: 68;Abbott 1974: 86). The 3 fringes are also found in E. multicarinata (Dall 1889), from North Carolina to north Caribbean, E. 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 E. inornata and E. 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 E. 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, E. itanhura cannot be confused with E. multicarinata.