16.6 Wednesday, Jan. 4 Upstream colonization of Australasia by Neotropical Opiliones (Arachnida) SHARMA, P.P.*; GIRIBET, G.; Harvard University; Harvard University email@example.com
The species richness and endemism of the Southwest Pacific are traditionally held to result from dispersal from Australasian continental landmasses (e.g., Australia, New Guinea, Southeast Asia), in concert with prolonged isolation. In the present study, the phylogeny of the circum-Pacific arachnid family Zalmoxidae (Opiliones, Laniatores) was investigated using a six-gene dataset under dynamic homology using parsimony, and static homology using maximum likelihood and Bayesian inference approaches. Ages of clades were inferred using BEAST v. 1.6.1 and ancestral area reconstructions were inferred using a DEC model, as implemented in the program Lagrange. Topologies across all analyses support the monophyly of Zalmoxidae and a Neotropical origin of this clade. Neotropical lineages within Zalmoxidae form a paraphyletic grade with respect to a derived Indo-Pacific clade. This topology, the molecular dating, and the relative phylogenetic placement of New Guinean and Southeast Asian lineages support a scenario of upstream colonization of Australasia by a Neotropical radiation. This highly uncommon biogeographical signal is contrasted with traditional views of Southwest Pacific biogeography.