On the identity of Leptoxis taeniata - a misapplied name for the threatened Painted Rocksnail (Cerithioidea, Pleuroceridae).

Paul D. Johnson,Nathan V. Whelan,Jeffrey T. Garner,Ellen E. Strong

doi:10.3897/zookeys.697.14060

Abstract

The Painted Rocksnail, currently known as Leptoxis taeniata, is a federally threatened species native to the Mobile River basin in Alabama, USA. Presently restricted to four disjunct populations, the species is at considerable risk of extinction after a range decline of over 95% in the 20th century because of habitat alteration following impoundment of the Coosa River. Here, we reassess the identity and historical range of the Painted Rocksnail to improve communication and conservation efforts for the species. We determined that L. taeniata is a synonym of L. picta and that the name L. taeniata has been misapplied to the current concept of the Painted Rocksnail for which L. coosaensis is the oldest available name. Leptoxis coosaensis and L. picta are herein redescribed. After examination of historical material, we determined that records of the Painted Rocksnail outside the Coosa River drainage were misidentifications. Thus, we redefine the historical range of the Painted Rocksnail as restricted to the Coosa River and select tributaries above the Fall Line at Wetumpka, Alabama, rather than extending into the Alabama River as previously thought. Leptoxis coosaensis is in dire need of conservation, and management plans should take into consideration the revised historical range of the species.

Highlights

The Painted Rocksnail is a riverine gastropod in the family Pleuroceridae that is listed as threatened under the US Endangered Species Act (Clark 1998)
We considered the historical range of the Painted Rocksnail as presently understood from a biogeographic perspective
The name L. taeniata has long been associated with an incorrect historical distribution for the Painted Rocksnail and further use of the name could perpetuate this error and create confusion for future management plans

Summary

Introduction

The Painted Rocksnail is a riverine gastropod in the family Pleuroceridae that is listed as threatened under the US Endangered Species Act (Clark 1998). Conrad characterized L. taeniata as, “oval, or oblong; olivaceous, with dark green spiral bands, four on the body whorl; one whorl of the spire not eroded, often longitudinally produced” (Conrad 1834b: 63) This vague description could apply to several Mobile River drainage Leptoxis species including L. picta (Conrad, 1834) (Conrad 1834a), L. ampla (Anthony, 1855), and the current concept of the Painted Rocksnail. We located an uncatalogued lot of four specimens containing another possible paralectotype at the Natural History Museum in London (NHMUK; ex Cuming collection), again labeled with the locality as “Alabama” (Fig. 5D) The latter lot is accompanied by an original J.G. Anthony label, annotated in his hand, “the separate one is authentic, marked so by Conrad himself, are not the others mature forms of the same?” one specimen is no longer conspicuously separated from the rest, we have concluded that the smallest specimen within the lot may be the specimen referred to in Anthony’s note. We question whether any pleurocerid species could be reliably distinguished based on minor differences in habitat preference as we have often observed individuals of the same Leptoxis species to inhabit many different microhabitats (i.e. near the banks and in the main current, both pebble and bedrock substrates; Whelan et al pers. obs.)

Results

Anculosa picta—Tryon 1873

Discussion