Host use of the elkhorn coral crab Domecia acanthophora (Brachyura: Domeciidae), with a phylogeny of the genus

Coral-dwelling crabs form a diverse community on coral reefs, and various families independently colonised scleractinian corals. Species of Domecia have a circumtropical distribution, with two known species in the Indo-Pacific, one in the West Atlantic and one in the East Atlantic. New host records for the West Atlantic species D. acanthophora are recorded from Guadeloupe, as well as the first dwellings in Acropora prolifera from Curaçao. Here we provide an overview of all known hosts of Domecia species and, based on COI mtDNA, the first phylogeny of the genus. The coral Orbicella faveolata and the sponge Callyspongia sp. are recorded as new hosts for D. acanthophora. Host records for this species now include eight scleractinian hosts, Millepora fire corals and records on sponges. Our phylogenetic reconstruction shows that D. acanthophora is closest to the wide-ranging Indo-Pacific species D. hispida, and more distantly related to D. glabra. Domecia acanthophora appears to be less host specific than its congeners D. hispida and D. glabra that predominantly associate with Pocillopora and Acropora corals, respectively. Differences in host-specificity between Indo-Pacific and Atlantic species are briefly discussed in the light of similar observations on other coral-dwelling crab species.