Iiiveitebialc Biology 122(2): I 14-125. © 2003 American Microscopical Society. Inc.

Abstract. The superfamily Cocculinoidea is a group of marine, deep-water, limpet-like gastro-pods. Recent speculation surrounding their affinities has concentrated on their placement within the Ga.stropoda. However, phylogenetic relationships within the Cocculinoidea, especially the monophyly of families and genera within the group, remain poorly understood. Phylogenetic analysis of 31 morphological characters for 15 cocculinoidean taxa and 2 outgroups resulted in a single most parsimonious tree, length = 70, CI =0.62, and RI=0.7I. Monophyly of the Cocculinoidea, Ct)cculinidae, and the genera Cocciilina and Coccopigya was supported; Par-acocculina and Coccocrater were found to be paraphyletic. Character optimization demon-strates that many characters often cited as diagnostic of various taxa, are often homoplastic and/or synapomorphies at different hierarchical levels. Additional key words: morphology, cladistics, deep-sea The Superfamily Cocculinoidea is a group of ma-rine, deep-water limpets that inhabit primarily bathyal to hadal depths. Following a series of studies near the turn of the century (Dall J882: Dautzenberg & Fischer 1900; Pelseneer 1900; Thiele 1903, 1908, 1909), the anatomy and systematics of these limpets remained es-sentially ignored for more than 50 years. After this long hiatus, interest in the poorly known group was vitalized by the investigations of Moskalev (1971