Larval data suggest a species complex in Athanas dimorphus Ortmann, 1894 (Decapoda: Alpheidae): Description of the zoea I from Western Atlantic and larval review of Athanas Leach, 1814

The shrimp Athanas dimorphus is considered an alien species in Western Atlantic. Larval morphology is known from the Indian Ocean, but it has been suggested that the species could actually be a species complex. Our aim was to describe the first zoeal stage of A. dimorphus from Brazil, review the larval morphology of Athanas and document inter- and intraspecific morphological variability within the genus and its taxonomic implications. Our descriptions and illustrations were based on larvae hatched in the laboratory from two females sampled in Pernambuco, which were compared to larval descriptions from the literature review. Morphological variations were found among first stage zoeas of this species from four localities (Brazil, Egypt, India and Pakistan), mainly in relation to segments, setae and aesthetascs of the antennule; setae on the basis of the maxilla; segments on the endopod of the second maxilliped and setae on the telson. The larval data analyzed here supports that A. dimorphus comprises a species complex. A taxonomic revision of this species complex, including specimens from Tanzania (type locality), is needed based on integrative taxonomy using adult and larval morphology (adults and larvae) coupled with genetics.