ELECTROPHORETIC AND MORPHOLOGICAL EXAMINATION OF AUSTROCOCHLEA-CONSTRICTA (GASTROPODA, TROCHIDAE) - A SPECIES COMPLEX

An analysis of allele frequencies at five polymorphic enzyme loci of o ne mainland Australian and four Tasmanian populations of Austrocochlea constricta revealed that three readily distinguishable morphs were th ree species. These were identified as A. constricta, A. porcata and A. brevis sp. nov. In sympatric populations, two diagnostic loci separat ed A. constricta and A. brevis (PEP-A and AAT-2), two separated A. por cata and A. brevis (PEP-A and AAT-2), and one separated A. porcata and A. constricta (PEP-A). With the exception of the last, these loci wer e also diagnostic in allopatric populations. In addition, significant differentiation was observed at most non-diagnostic loci in sympatric populations. A. porcata and A. constricta, but not A. brevis, showed l imited, although significant, interpopulation differentiation at two o f the five loci, which was attributed to geographic isolation. Examina tion of genetic distance data showed the three species to have non-ove rlapping values, but variance overlap meant that the intra-species pop ulation affinities were unresolved. Radulae of the three species were assessed qualitatively and quantitatively from scanning electron micro graphs. Inter-specific comparisons of tooth dimensions revealed no sig nificant differences and, despite a less variable tooth shape in A. co nstricta than in A. porcata or A. brevis, no consistent features of ra dular morphology were found to distinguish any one species. Morphologi cal descriptions of the shells and anterior soft body regions are give n to enable ready field identification of the species, and their known distributions are outlined.