The four species of Excorallana known from the Gulf of California, including two new species, are described and figured: Excorallana tricornis occidentalis Richardson, 1905; Excorallana truncata (Richardson, 1899); Excorallana bruscai n. sp.; and Excorallana
houstoni n. sp. Excorallana kathyae Menzies, 1962, a species previously recorded from the Gulf (Menzies, 1962; Monod, 1969; Schultz, 1969; Brusca, 1980) was recently synonymized with E. truncata (Delaney, 1982). Species of Excorallana have previously been distinguished
by the morphology of the mouthparts and pereopods (Stebbing, 1904; Richardson, 1905). The presence of a small molar process and lacinia mobilis on the mandibles of Excorallana tricornis occidentalis, E. truncata and E. bruscai, previously unreported, supports Menzies et al. (1955)
and Brusca's (1981) placement of the family Corallanidae between the Cirolanidae and the Aegidae in a proposed phylogenetic lineage of flabelliferan isopods. A key to all known species of Excorallana is presented, along with comments on the ecology and biogeography of the genus.
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