No abstract

The subspecies A. barbatus barbatus as currently recognized comprises two distinct marginally sympatric morphs. Differences in external and skeletal morphology and the apparent absence of hybrids in the narrow zone of overlap imply that each morph is genetically distinct and not a particular phenotypic expression of one genotype. The low density of one morph in the region of overlap, and hybrid inferiority as suggested by laboratory cross-mating, may each be partly responsible for the apparent lack of hybridization. On this basis each morph is given full species status, one being the typical form A. barbatus (Cuvier) while the other is referred to A. vitticeps Ahl. With the morphological differences between these two species as the criteria for species status, the other described subspecies of A. barbatus are examined and likewise elevated to species rank as follows: A. minor Sternfeld, A. minimus Loveridge and A. microlepidotus Glauert. Two additional new species A. mitchelli, sp. nov., and A. nullarbor, sp. nov., are described within the species-group.