A Review on Taxonomy and Distribution of the Genus Echis Merrem, 1820 (Serpentes: Viperidae) with Special Reference to the Middle East.

Saw scaled vipers of the genus Echis belong to the family Viperidae and subfamily Viperinae. These vipers are widely distributed from East Africa to Southwest and Central Asia. Echis bite is one of the major causes of mortality in the world. Different populations of these medically important snakes have different venom composition, and the relevant antivenom is highly species-specific. Echis has a complex taxonomic history. For many years, only two species were recognized (i.e., Echis coloratus and E. carinatus). Over the past 50 years, the number of species have been raised to 12, of which six species reside in the Middle East. Phylogenetic studies show that the genus Echis fall into four species groups: the E. carinatus, E. coloratus, E. ocellatus and E. pyramidum groups. Until recently, only E. carinatus in Southwest Asia and India and E. coloratus in Arabia were assigned to the Middle East. Several morphological and phylogenetic studies raised the number of Echis species in the Middle East from two to six. These Middle Eastern vipers belong to three different species groups. An Asian, an Arabian and an African group. Distribution and basal split of the genus Echis, likely have been shaped by vicariance and tectonic events, which have separated or connected the land masses. In this study, a brief review on biogeography, taxonomy and distribution of the genus especially in the Middle East is presented.