Notes on the identification and speciation of Heteropoda (Gastropoda)

INTRODUCTION Specimens of Heteropoda, especially of Atlantidae, which are damaged by the nets and have lost their shells by the action of preservatives are usually considered to be hardly identifiable. Tokioka (1961) used the opercula as a new source of morphological information for the study of the shell-less Atlantidae. The laborious preparation of opercula enables only the identification of some species. The occurrence of groups of closely related taxa showing only slight morphological differences is responsible for other difficulties in identification. Recent expeditions, like the Cicar Expedition, the Eastropac Expeditions and the Acre project provided samples with large quantities of damaged heteropods, which induced me to look for a simple method to identify the damaged specimens with a high degree of certainty. The results of this attempt are given below together with a discussion on some problems in speciation of heteropods. ACKNOWLEDGEMENTS The author is very much indebted to Prof. Dr. L. D. Brongersma, who frequently made it possible for him and his co-workers to borrow material from the Rijksmuseum van Natuurlijke Historie, Leiden. That with the method discussed below certainly a large part of previously borrowed material can be identified is one of the reasons to regard it as an honour to dedicate this paper to Professor Brongersma. The staining method used for the heteropods has been developed by Mr. A. F. de Fluiter, to whom the author is very thankful. METHOD All specimens from a sample are stained at the same time and mounted,