Systematic revision of the Kalliapseudidae (Crustacea: Peracarida: Tanaidacea) and the population genetic structure and phylogeography of a species along the southeastern and Gulf coasts of North America

The Kalliapseudidae is a family of shallow burrow-dwelling marine and estuarine tanaidaceans. There are currently 39 known species of 12 genera and three subfamilies. They are primarily circumtropical in distribution; however, several species are found in temperate waters. The phylogeny of Kalliapseudidae is assessed to test the monophyly of currently accepted subfamilies and genera, based largely on examination of material loaned from various museums and institutions. Multiple exemplars from other apseudomorph families were also included in the ingroup to test the monophyly of the family. Parsimony analyses included 41 terminal taxa and 64 binary and multistate morphological characters. Analyses based on successive weighting resulted in 20 most parsimonious trees (CI = 0.675, RI = 0.917). The strict consensus tree of these most parsimonious trees supported Kalliapseudidae, Kalliapseudinae, Tanapseudes, Cristapseudes, and Mesokalliapseudes as monophyletic. The genus Kalliapseudes could not be resolved, but constraining it to be monophyletic resulted in a significantly worse tree (P = 0.03). The subfamilies Hemikalliapseudinae and Tanapseudinae were recovered as polyphyletic and paraphyletic, respectively, but without support. Constraining them to be monophyletic did not result in a significantly worse tree ( P = 0.20). Results indicated high levels of homoplasy in three morphological characteristics traditionally used to differentiate groups. Alokalliapseudes macsweenyi is transferred back to the genus Mesokalliapseudes, rendering Alokalliapseudes a junior subjective synonym. Fourteen new taxa, including eight species of Kalliapseudes and one each of the genera Cristapseudes, Mesokalliapseudes, Transkalliapseudes, and a new genus, were discovered and described.;The kalliapseudid tanaid Mesokalliapseudes macsweenyi is an important component of coastal regions of eastern United States, ranging from South Carolina to Mississippi. The DNA sequence variation at the mtDNA COI locus was examined in eight populations to assess the population genetic and phylogeographic structure. Results showed significant genetic structure among the populations and between the Atlantic/Gulf regions. All demographic analyses inferred a population expansion in the Gulf of Mexico, which might be in accordance with a post-Pleistocene range expansion. However, the significant population structure exhibited by the northern Gulf of Mexico populations is a pattern consistent with some degree of isolation and the possible persistence of northern refugia. These results are consistent with expectations based on the developmental mode (direct development) of M. macsweenyi.