Zilchogyra franzi Weyrauch, 1965 (Gastropoda: Charopidae), a minute landsnail rediscovered in Sierra de la Ventana (Southern Pampas, Argentina)

DELHEY V. K., PIZÁ J. & S. BURELA

ZOOTAXA

MAGNOLIA PRESS

Año: 2010 vol. 2450 p. 61 - 64

1175-5326

Zilchogyra franzi was described on the basis of a single specimen (holotype in Fundación Miguel Lillo: FML 1217, Fig. 1) from the Ventania mountain system (Weyrauch 1965b) and this was so far the only publication on this species. Weyrauch (1965b) described the shell and gave a brief account of the habitat, based on the information provided by the collector Dr. Herbert Franz. Franz had found Z. franzi in a ravine in Sierra de la Ventana, in a humid hollow in the rock, lined with dark soil with ferns and “bromeliads” (probably Eryngium spp., Apiaceae). Zilchogyra franzi was found in the company of the exotic Punctidae Paralaoma servilis (Shuttleworth, 1852). In contrast with Z. franzi, P. servilis is common in Sierra de la Ventana; we found it in the soil, in litter, under rocks and under the bark of Eucalyptus trees. Paralaoma servilis has been described several times under different names in Argentina and different parts of the world (Hausdorf 2002). There is an early record of Radiodiscus pilsbryi Hylton- Scott, 1957 (a junior synonym of P. servilis) for Sierra de la Ventana (Fernández 1973). Using the method of Solem (1976) (Figs. 4–6), we measured 32 shells, ranging from 2.2 to 5.4 mm in major diameter. Below we provide a redescription of Z. franzi that is based on adult specimens, documents conchological variability and provides novel information on shell microsculpture derived from SEM micrographs (SEM Evo 40 Leo 2003).