Monday, September 19, 2011

The Moluccan Short-tailed Snakes - The Most Basal Homalopsids

The Moluccan Short-tailed Snakes of the genus Brachyorrhos are poorly-known, terrestrial–fossorial snakes that eat worms and are endemic to eastern Indonesia. During the past 200 years the snakes in this genus have been assigned to at least six different families. In 1987 Samuel McDowell suggested that they may be homalopsids. This seemed unlikely- homalopsids are aquatic, they eat fish, crustaceans, and frogs; homalopsids also have enlarged grooved fangs on the rear of the maxillary bone, and none of the known species have a rostral scale that separates the nasal scales. However, in my 2007 book, Homalopsid Snakes, Evolution in the Mud, I listed the genus as being of uncertain status. In a recent paper, Murphy et al. (2011) recovered the first molecular sequences for Brachyorrhos and tested the position of the genus within snake phylogeny. Bayesian and Maximum Likelihood analyses of three mitochondrial and one nuclear gene strongly resolve Brachyorrhos within the rear-fanged semi-aquatic family Homalopsidae, as the sister to all other genera and sampled species. Thus, Brachyorrhos makes an excellent model for a possible ancestor of the homalopsids, an ancestor that was terrestrial-fossorial and fang-less and produced decedents that evolved aquatic lifestyles, rear-fangs, and fish-crustacean diets.

Murphy, J. C., Mumpuni, K. L. Sanders. 2011 (in press). First molecular evidence for the phylogenetic placement of the enigmatic snake genus Brachyorrhos (Serpentes: Caenophidia)  Molecular Phylogenetics and Evolution, doi:10.1016/j.ympev.2011.08.013.

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