A relict in New Caledonia: phylogenetic relationships of the family Troglosironidae (Opiliones: Cyphophthalmi).

The species richness and endemism of New Caledonia are traditionally held to result from the main island's Gondwanan origin and progressive diversification subsequent to extended isolation. Recent studies have challenged this hypothesis, promoting a scenario of recent origins and diversifications of New Caledonian arthropod groups. In the present study, the phylogeny of the endemic harvestman family Troglosironidae (Opiliones: Cyphophthalmi) is investigated using DNA sequence data from two nuclear ribosomal genes (18S rRNA and 28S rRNA) and two mitochondrial genes (the protein-coding cytochrome c oxidase subunit I and the ribosomal 16S rRNA). Phylogenetic analyses support the monophyly of Troglosironidae and a scenario of an ancient (> 200 Ma) origin of the family, with subsequent diversification of extant lineages in the Eocene. These results corroborate the relictual nature of taxa among New Caledonia's biota while being consistent with diversification in accordance with geological events in the Eocene.