A new species of Brachyorrhos from Seram, Indonesia and notes on fangless homalopsids (Squamata, Serpentes)

Abstract

Homalopsid snakes are monophyletic and contain two major subclades: a fangless clade and rear-fanged clade. They are distributed in South Asia, Australasia, and the Western Pacific. The fangless clade is restricted to the eastern Indonesian Archipelago and the island of Sumatra and is poorly known in terms of its natural history. Molecular data support the eastern Indonesian fangless endemic genus Brachyorrhos as the sister to the rear-fang clade. Here we recognize the identity of the Brachyorrhos population from the island of Morotai as B. wallacei and describe a new species of dwarf Brachyorrhos from the island of Seram, Malukus, Indonesia. The new species can be distinguished from all congeners by a lower number of ventral scales, the presence of a preocular scale and a loreal scale, as well as its exceptionally diminutive size. The new species is a candidate for the smallest alethinophidian snake. The three fangless genera, Brachyorrhos, Calamophis, and Karnsophis, have been suggested to form a clade of homalopsid snakes restricted to the Indonesian Archipelago, and we discuss their biogeography. KEYWORDS: biogeography, Calamophis, Homalopsidae, Karnsophis, small snakes