A new species of stygobitic snail in the genus Antrorbis Hershler & Thompson, 1990 (Gastropoda, Cochliopidae) from the Appalachian Valley and Ridge of eastern Tennessee, USA.

Annette S Engel,Evelyn B Pieper,Matthew L Niemiller,Nicholas S Gladstone,Katherine E Dooley,Evin T Carter,Nathaniel F Shoobs,Kathryn E Perez

doi:10.3897/zookeys.898.46917

Abstract

A new species of cave snail (Littorinimorpha: Cochliopidae) in the genus Antrorbis is described from the dark zone of two caves in the Appalachian Valley and Ridge province in eastern Tennessee, United States. The Tennessee Cavesnail, Antrorbis tennesseensis Perez, Shoobs, Gladstone, & Niemiller, sp. nov. is distinguished from its only known congener, Antrorbis breweri, by the absence of raised tubercles on its finely spirally striate protoconch, and its unique radular formula. Moreover, A. tennesseensis is genetically distinct from A. breweri based on substantial divergence at the mitochondrial CO1 locus. This is the first cavesnail to be described from the Appalachian Valley and Ridge (AVR) physiographic province in the state of Tennessee, which previously represented a substantial gap in the distribution of stygobitic (i.e., aquatic, subterranean-obligate) gastropods.

Highlights

Among the hydrobioid snails (i.e., Hydrobiidae s.l.; Davis 1979) are a morphologically diverse group of minute gastropods living in freshwater subterranean habitats in karstic regions of North America (Hershler and Holsinger 1990; Niemiller et al 2019)
We describe a new species of stygobitic snail, Antrorbis tennesseensis, which is distinguished from its only congener A. breweri by the absence of raised tubercles on the spiral striae on the external protoconch and substantial divergence at the mitochondrial cytochrome oxidase subunit 1 (CO1) locus
Individuals from the third population discovered in this region (Pedigo Cave), despite being morphologically similar to A. tennesseensis, form a paraphyletic group with A. tennesseensis in the maximum likelihood (ML) phylogeny

Summary

Introduction

Among the hydrobioid snails (i.e., Hydrobiidae s.l.; Davis 1979) are a morphologically diverse group of minute gastropods living in freshwater subterranean habitats in karstic regions of North America (Hershler and Holsinger 1990; Niemiller et al 2019). During ongoing cave biological inventory efforts to address the previously identified sampling gaps in the AVR of eastern Tennessee, we discovered three distinct populations of an undescribed stygobitic snail within the Tennessee River watershed of Roane and Knox counties, Tennessee These snails resembled the Manitou Cavesnail, Antrorbis breweri Hershler and Thompson 1990 described from Fort Payne, Alabama, and would represent a ca. We generate a phylogeny to test the position of Antrorbis among other stygobitic and non-stygobitic Cochliopidae

Materials and methods

27 January 2019

Findings

Discussion