Old species and new concepts in the taxonomy of Pomacea (Gastropoda: Ampullariidae)

RESUMO

The taxonomic history of the South American genus Pomacea Perry, 1810, and some shifts of systematic concepts during recent decades are briefly reviewed. Too many pre-evolutionist, shell-defined species created a gibberish, the only acceptable solution of which being perhaps a conventional, somewhat authoritarian decision based on expertise. The addition of other sources of morphological, biochemical, ecological or genetic information should not solve the problem if it is not accompanied by a sound reappraisal of the species concepts. Since the assumptions of each concept differ, any correspondence between them is irrelevant, and may drive to incompatible results. The shell variability of Pomacea canaliculata was acknowledged for most authors throughout more than a century. A recent insight into its life-history traits demonstrated they are as variable as the morphology. These findings stress the need of determining the ecological identity of any pest apple-snail population at a local scale, because its invading ability may be not exactly correlated to its taxonomical identity. Probably, all the canaliculata-like apple snails constitute a single, very variable "species" in most senses, even though different subsets may be recognized under other incommensurable concepts.