Bulimulus beckianum

Simone, Luiz Ricardo L. & Casati, Rafael, 2013, New land mollusk fauna from Serra da Capivara, Piauí, Brazil, with a new genus and five new species (Gastropoda: Orthalicoidea, Streptaxidae, Subulinidae), Zootaxa 3683 (2), pp. 145-158 : 156-157

Beckianum beckianum (Pfeiffer, 1846)

( Figs. 51 –55)

Synonymy see Tillier (1981).

Diagnostic features. Shell of about 6.5 mm. Color pale brown, translucent. Periostracum thin, shining. Outline turriform; width ~ 35 % of length ( Figs. 51–53). Protoconch of 2.5 whorls, glossy, tall, suture well-marked; smooth; occupying ~ 14 % of shell length and ~ 32 % of shell width ( Figs. 54 –55); border protoconch-teleoconch unclear, orthocline. Spire of ~ 7 rounded, narrow whorls, growth of whorls continuous up to fourth whorl, angle ~ 40 ° ( Figs. 54 –55); remaining whorls of similar size ( Figs. 51–53); suture well-marked. Sculpture uniform series of axial, narrow ribs, from suture to suture, ~ 40 in penultimate whorl; interspaces between ribs equivalent to 4 times their width. Peristome not deflected, orthocline ( Fig. 52). Aperture rounded, occupying ~ 20 % of shell length and ~ 45 % of width; lacking teeth; outer lip rounded, simple; inner lip highly concave, superior half slightly convex, inferior half also almost straight and narrow. Callus thin inconspicuous. Umbilicus absent.

Measurements (in mm): MZSP 112411: 6.5 by 2.2; MZSP 111842: 4.8 by 2.2.

Distribution. Only known from type locality.

Habitat. Caatinga semi-dry environment; collected inside caves.

Material examined. BRAZIL. Piauí; Serra da Capivara ; Coronel José Dias municipality, close to Sítio do Mocó town, Cave Toca de Cima dos Pilão, 8 ° 51 ’47.10”S 42 ° 33 ’26.96”W, MZSP 112411, 1 shell, MZSP 111842, 1 shell (R. Casati col, 2012).

Systematic remarks. The main character of the genus Beckianum is the narrow whorls in their height, producing a multispiral, narrow whorled, turriform shell. The examined specimens clearly possess these characters. As the genus has a single species— B. beckianum , from Mexico to São Paulo—( Simone, 2006, and references therein) there is that single species to identify. However, the examined specimens have a more developed axial sculpture and a protoconch with 1 more whorl if compared with the typical B. beckianum ( Simone, 2006, fig. 685). Despite these differences, the description of a new species is considered premature.

The extraordinary distribution of B. beckianum is possibly an indicative of anthropic transportation, as well as that under this epithet may exist several similar-shelled species. Further studies are certainly necessary as normal for subulinids.