Naja siamensis, a cryptic species of venomous snake revealed by mtDNA sequencing

Because of possible variation in venom composition, an understanding of venomous snake systematics is of great importance for the optimization of antivenom treatment of snakebite patients. Intraspecific variation in the morphology of many venomous snakes complicates the definition and indentification of some species when allopatric populations are involved. Selectively neutral or near-neutral mtDNA sequences can reveal evolutionary relationships obscured by ecogenetically-caused morphological variation. We use comparative sequencing of the cytochrome oxidase subunit 1 gene to reveal the existence of a widespread, cryptic species of spiting cobra from southeast Asia. This species,Naja siamensis, is widely sympatric with other Asiatic cobra species. This may be of considerable medical significance, and calls for further research into venom composition in Asiatic cobras.     

A dicephalic yellow anaconda snake,Eunectes notaeus (Serpentes: Boidae), from Southern Pantanal,Brazil

We describe a case of dicephalism in a yellow anaconda snake, Eunectes notaeus, from southern Pantanal, Brazil. The specimen exhibits two heads and two long necks, which are united on the anterior third of the body. Two hearts, three lungs, two livers, and two stomachs are also present. The left heart is larger and more cranial than the right heart although they are in the normal position. Radiographs revealed approximately 64 vertebrae in the right neck, 57 in the left neck, eight in the fusion zone, 202 in the trunk, and 52 in the tail. According to the classification adopted in the present study the specimen herein described is a proarchodichotomous specimen. This is the first record of dicephalism in Eunectes. Further, this snake represents the 28th documented case of dicephalism within the family Boidae and the 1088th case in snakes.     

Asiatic cobras: Systematics and snakebite

Summary The population affinities of the Asiatic cobras of the genusNaja are investigated, using multivariate analysis of a range of morphological characters. This complex, which was formerly thought to be monospecific, consists of at least eight full species. In some cases, species whose bites require different antivenoms occur sympatrically. The new understanding of the systematics of the Asiatic cobra complex calls for a reappraisal of cobra antivenom use in Asia, and for more research into venom composition.