Electrophoretic and morphological examination of Austrocochlea constricta (Gastropoda: Trochidae): A species complex

Abstract

An analysis of allele frequencies at five polymorphic enzyme loci of one mainland Australian and four Tasmanian populations of Austrocochlea constricta revealed that three readily distinguishable morphs were three species. These were identified as A. constricta, A. porcata and A. brevis sp. nov. In sympatric populations, two diagnostic loci separated A. constricta and A. brevis (PEP-A and AAT-2), two separated A. porcata 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 were 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 limited, although significant, interpopulation differentiation at two of the five loci, which was attributed to geographic isolation. Examination of genetic distance data showed the three species to have non-overlapping values, but variance overlap meant that the intraspecies population affinities were unresolved. Radulae of the three species were assessed qualitatively and quantitatively from scanning electron micrographs. Inter-specific comparisons of tooth dimensions revealed no significant differences and, despite a less variable tooth shape in A. constricta than in A. Porcata or A. brevis, no consistent features of radular morphology were found to distinguish any one species. Morphological descriptions of the shells and anterior soft body regions are given to enable ready field identification of the species, and their known distributions are outlined.