Phylogeny of the family Spongicolidae (Crustacea: Stenopodidea): evolutionary trend from shallow-water free-living to deep-water sponge-associated habitat

Abstract

The phylogenetic relationships within the family Spongicolidae were examined based on a cladistic analysis of 38 adult morphological characters with reference to two outgroup species of the family Stenopodidae. The strict consensus tree identified Microprosthema as the most basal genus, followed by Paraspongicola , Spongicola and the remaining genera. The Spongicoloides represents the most derived genus among spongicolids. The genera Spongicola, Spongicoloides and Spongiocaris should be redefined, because they formed paraphyletic clades. The cladogram indicates that symbiosis with the hexactinellid sponges is coincident with the loss of gills, exopods on maxillipeds 2 and 3, and with the loss of spination on carapace, pereopods, abdomen, tail fan etc. These losses in the spongicolids are thought to be secondarily derived in relation to their sponge-associated habitat.