Relationships within the Munnopsidae (Crustacea, Isopoda, Asellota) based on three genes

Osborn, K. J. (2009). Relationships within the Munnopsidae (Crustacea, Isopoda, Asellota) based on three genes. - Zoologica Scripta, 38, 617-635. The Munnopsidae are a diverse group of asellote isopods that are an important component of deep-sea fauna. Morphologically-based phylogenetic inference attempts have proven to be of limited use due to the ecological and morphological diversity within the clade. Monophyly of the family is well-established but relationships within the group remain unresolved. This project is the first molecularly-based effort focused specifically on resolving phylogenetic relationships within the Munnopsidae. Partial 28S and COI and complete 18S genes were sequenced for 28 asellotes, 15 additional taxa were included from which only one or two of the three target sequences could be obtained, and 18S sequences for five additional taxa were available from GenBank. Sequences were analysed both as individual genes and in combination using Bayesian and maximum parsimony approaches. Each gene provided a phylogenetic signal that could be identified in the combined analyses, with 18S analyses providing the most resolution of phylogenetic relationships. The available representatives of subfamilies Munnopsinae and Ilyarachninae were monophyletic, as was the genus Munneurycope. Relationships within the subfamily Munnopsinae were well-resolved by thorough taxon sampling, several new species were placed, and the need for taxonomic revision of Munnopsis/Munnopsoides was supported. These analyses supported putative Eurycope paraphyly and emphasized the need for careful revision of this highly variable genus. Tytthocope was sister to Munnopsurus. Syneurycope was suggested as the sister group to the ilyarachnines. Combined analyses provided increased support for clades suggested in at least two individual gene analyses and for clades not strongly contradicted by individual analyses. Further work is required to fully resolve the munnopsid phylogeny and should consist of increased taxon sampling for the complete 18S sequence and possibly identification of at least one slowly evolving, nuclear protein-coding gene to resolve the basal polytomy and enable placement of the root.