Snakes in the
family Homalopsidae have been long considered semiaquatic or aquatic forms with
live birth and rear-fangs. In 2011, Brachyorrhos was confirmed as a member of
the family (Murphy et al. 2011), but Brachyorrhos is terrestrial, feeds on
worms, and has no rear fangs. The DNA evidence suggested Brachyorrhos was the
most basal member of the family. Further investigation into the genus suggested
it was restricted to Eastern Indonesia, the Moluccas, Aru, and the Raja Ampat Islands. However, the literature
suggested it was also present in western New Guinea, frequently mentioning
Brachyorrhos jobiensis, a species described from Yapen Island, known only from the type specimen which was destroyed in World War II.
For all of the 20th century, two species were thought to comprise the genus Brachyorrhos, B. albus and B. jobiensis because G. A. Boulenger had synonomized several previously described species under the name Brachyorrhos albus. A review of
museum specimens found four species of Brachyorrhos in the Moluccas, one species
on Seram and nearby Ambon (B. albus), one species on Buru (B. gastrotaenius),
one species on Ternate (B. raffrayi), and an undescribed species on Halmahera,
that we named B. wallacei (Murphy et al. 2012).
Despite the fact that Ternate (a volcanic island) is only 14 km off the
coast of Halmahera, the genetic difference between the snakes on the two
islands was 7.2%, suggesting they had separated from their common ancestor
quite some time ago.
Within the museum
specimens examined were six specimens labeled Brachyorrhos jobiensis, all from
extreme western New Guinea, in an area known as the Bird's Head. The Bird's
Head is a biodiversity hot spot that has been poorly explored for squamate
reptiles. Examination of the six specimens revealed three different undescribed species, based upon their body form. Two of the species had
cylindrical bodies and stout tails (about 9 to 12 % of the body length) and
appear to be cryptozoic/ fossorial/ aquatic species. The third species has a remarkable
lateral compression of the body, an exceptionally abbreviated tail (about 3% of
the body length) suggesting it is an aquatic form evolved from a fossorial
ancestor (Murphy, 2012).
The differences between jobiensis-like snakes and the Brachyorrhos were
striking, while they shared a considerable amount of morphology, the jobiensis
-like snakes had rounded heads, a reduced number of scales at the back end of
the body, a single internasal scale, and remarkably different looking tails.
While the morphology they shared suggested they are related.
It seems likely that more Brachyorrhos species will be found, in eastern Indonesia. And, further investigation into these interesting snakes may
provide insight into the evolution of fangs, as well as
the shift from terrestrial to aquatic or aquatic to terrestrial life styles.
Literature Cited
Murphy, J. C., Mumpuni & K. L. Sanders, 2011. First molecular evidence for the phylogenetic placement of the enigmatic snake genus Brachyorrhos (Serpentes: Caenophidia). Molecular Phylogenetics and Evolution, 61: 953–957.
