Meeting Abstract

30.4  Friday, Jan. 4  Systematics and evolution of Anachis and related taxa (Neogastropoda: Columbellidae) in the American tropics DEMAINTENON, Marta; Univ. of Hawaii, Hilo demainte@hawaii.edu

Columbellid gastropods are one of the more diverse groups of neogastropods in the modern marine biota, comprising over 600 nominal species worldwide. In the American tropics, one group of columbellids, the Strombina group, has been used as an exemplar taxon to study changes in marine faunal diversity during and after the closure of the Panamanian Isthmus. The Strombina group is unusual within the columbellids in that species in this group primarily favor soft sediments in deeper waters, whereas most columbellids tend to favor nearshore hard bottoms. Given this difference, the objective of this ongoing project is to investigate the systematics and evolution of some of the more diverse nearshore columbellid taxa, the genus Anachis and its supposed relatives Costoanachis, Parvanachis, and Glyptanachis. These are among the most diverse of the regional columbellid fauna, comprising about one third of the known Eastern Pacific and Western Atlantic species, and they are largely restricted to the region. The similar high diversity of these groups in both basins will provide an interesting contrast with the ecologically very different Strombina group species, which have a high eastern Pacific diversity, but few species in the Western Atlantic. Preliminary results at this stage of the project will address the monophyly of the nominal genera, their relationships within the Columbellidae, and their historical relationships within the tropical eastern Pacific and Caribbean basins.