Agkistrodon

Abstract: We used mitochondrial DNA sequences from three gene regions and two tRNAs (ND4, tRNA-HIS-SER, 12S, and 16S rDNA) to investigate the historical ecology of the New World pitviper clade Agkistrodon , with emphasis on the disjunct subspecies of the cantil, A. bilineatus . We found strong evidence that the copperhead ( A. contortrix ) is basal to its congeners, and that the cottonmouth ( A. piscivorus ) is basal to cantils. Phylogeography and natural history of the living terminal taxa imply that Agkistrodon primitively occupied relatively temperate habitats, with subsequent evolution of tropicality in ancestral A. bilineatus . Our best supported phylogeny rejects three gulf arc scenarios for the biogeography of A. bilineatus . We find significant statistical support for an initial divergence between populations on the east and west coasts of Mexico and subsequent occupancy of the Yucatan Peninsula, by way of subhumid corridors in northern Central America. Based on phylogenetic relationships, morphological and molecular divergence, and allopatry we elevate A. b. taylori of northeastern Mexico to species status. Taylor’s cantil is likely threatened by habitat destruction and small geographical range, and we offer recommendations for its conservation and management.

Abstract: BITES by common pit vipers create complex problems in the human victim that require complex solutions. No panacea is available, regardless of statements by some authorities. In the continental United States, common pit vipers include the rattlesnake, copperhead moccasin, and water moccasin; in south Texas, they are represented by the western diamondback rattlesnake (Crotalus atrox), copperhead moccasin (Agkistrodon contortix contortix), and water moccasin (Agkistrodon piscivorus leucostoma. Any physician who treats a pit viper bite must know the mechanical and physiological effects of the venom on the human victim, and he must apply the latest methods of medicine and surgery to prevent death, loss of limbs and digits, and loss of function (especially of the hand and fingers).1 Since 1966,I have seen and treated 200 patients with pit viper bites and have performed surgery on 140. These 140 patients are classified according to type of viper, sex, age, and area