Phylogeny, evolution and biogeography of the marine isopod subfamily Idoteinae ( Crustacea: Isopoda: Idoteidae).

Abstract

The patterns of spatial distribution attained by the genera of Idoteinae are discussed in light of a cladistic analysis of the suborder Valvifera and the subfamily Idoteinae. A geographic cladogram of temperate Gondwanan shores is proposed. The subfamily Idoteinae appears to form 2 principal lines of descent, both arising in the Triassic or Jurassic. One of these lines remained closely tied to the Southern Hemisphere (primarily Old World) temperate marine shores from which the Idoteinae is derived. The other line invaded the Northern Hemisphere and various New World environments, and more recently (Cenozoic) underwent a radiation in the American tropics. The success of this latter lineage may be due to certain morphological and life history adaptations not found in New World species of the former line. The Valvifera probably originated in the temperate Southern Hemisphere, at least by Permean/Triassic times. Global distribution patterns of some genera can be ascribed most parsimoniously to vicariance processes, and in others to dispersal, ecological, phenomena, or a combination of processes.-from Author