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Abstract
Acrochordus is a species-poor but highly distinctive aquatic snake genus currently
distributed from India to the western edge of the Pacific. We provide the first phylogeny
for the three extant species using Bayesian and parsimony analyses of one mitochondrial
and two nuclear gene sequences. Acrochordus javanicus is strongly recovered as sister
to A. arafurae+A. granulatus, counter to expectations from superficial ecology, external
phenotype and former taxonomy. We review and revise key fossil calibrations for dating
snake divergences. Bayesian relaxed-clock analysis of the two nuclear loci yields
deep interspecific divergences among extant species that occurred during the Miocene
approximately 16 and approximately 20Mya (million years ago), pre-dating at least
two of the three other living marine snake lineages. New morphological data for A.
arafurae, and our molecular timescale, provide support for the placement of fossil
taxon A. dehmi within the Acrochordus crown group, as sister to A. javanicus among
nominate species. Finally, Acrochordus phylogeny provides an improved basis for taxon
selection and character polarization in higher snake phylogenetics. Our study highlights
the three Acrochordus species as old and highly distinct lineages that comprise an
important component of the threatened Indo-Australian biodiversity.
Crown Copyright 2010. Published by Elsevier Inc. All rights reserved.