The members of this complex contain about 24 species in six genera. They range from eastern Europe and northwestern Asia eastward to Japan and have a discontinuous southward distribution into the Himalayas, southern India, Sri Lanka, Indochina, and Java. Five species occur in the Western Hemisphere, and they apparently had an ancestor nested in the Eastern Hemisphere crotalines, perhaps Gloydius. While these snakes have been assumed to form a clade, they may yet be shown to be polyphyletic. Howard K. Gloyd and Roger Conant reviewed these snakes in their 1990 book, Snakes of the Agkistrodon Complex, A Monographic Review. They wrote:
"On the basis of the information available to us, we believe that the snakes of the Agkistrodon complex constitute the most primitive group of the subfamily Crotalinae, and that they resemble their progenitors in numerous respects."
The Copperhead, Agkistrodon contortrix (Linnaeus, 1766). Photograph of a captive specimen from Douglas County, Kansas. This is a pattern less morph of the copperhead. Henry Fitch was the author of a classic copperhead field study done from 1948-1959 at the University of Kansas Natural History Reservation. More than 1500 snakes were recorded 2,016 times. Fitch found this species to be relatively sedentary, not moving at all, or moving only a few yards during a 24 hour period. Males were found to have a home range of about 24.5 acres, and females had a home range of about 8.5 acres. Males became sexually mature in their second summer, at a body size that could be as small as 0.42 m. Most females were sexually mature after their third hibernation, at a body size of about 0.52 m. Females usually produced litters in alternating years. Food was mostly small vertebrates and some insects (mostly cicadas and large moth larvae). (See: Fitch, 1960. Autecology of the Copperhead, University of Kansas Publications Museum of Natural History 13:85-288.)
The Copperhead, Agkistrodon contortrix (Linnaeus, 1766). A neonate born in captivity. Parent from Douglas County, Kansas.
The Copperhead, Agkistrodon contortrix (Linnaeus, 1766). Photographed in Union County, Illinois.
The Copperhead, Agkistrodon contortrix (Linnaeus, 1766). Photograph of a captive specimen shedding its skin, its origin is unknown.
The Copperhead, Agkistrodon contortrix (Linnaeus, 1766). Photographed in Douglas County, Kansas. A juvenile specimen in the field.
The Western Cottonmouth, Agkistrodon piscivorous (Lacepede, 1789). Photographed in Johnson County, Illinois. Typical defense behavior of this snake involves holding its position and opening its mouth to expose the lining which is usually (but not always) white.
The Western Cottonmouth, Agkistrodon piscivorous (Lacepede, 1789). A juvenile photographed in Union County, Illinois. Neonates and juvenile cottonmouths have a sulfur colored tail tip used as a visual lure for frogs and lizards, as do many pit vipers
The Western Cottonmouth, Agkistrodon piscivorous (Lacepede, 1789). Photographed in Johnson County, Illinois. Typical defense behavior of this snake involves holding its position and opening its mouth to expose the lining which is usually (but not always) white.
The Western Cottonmouth, Agkistrodon piscivorous (Lacepede, 1789). Photographed in Johnson County, Illinois. Typical defense behavior of this snake involves holding its position and opening its mouth to expose the lining which is usually (but not always) white.
The Malaysian Pit Viper, Calloselasma rhodostoma (Kuhl, 1824). Photographed in central Thailand. This snake was located in a disturbed area next to a tropical deciduous forest. It was in a patch of dense, weedy vegetation and was located only with the help of an implanted radio transmitter.
The Malaysian Pit Viper, Calloselasma rhodostoma (Kuhl, 1824). Photographed in southern Thailand on the campus of Prince of Songhkla University at Hat Yai. It was found at night in a bamboo thicket on the campus.
The Malaysian Pit Viper, Calloselasma rhodostoma (Kuhl, 1824). Photographed in Thailand, a captive specimen of unknown origin.
The Hump Nosed Viper, Hypnale hypnale (Merrem, 1820). Photographs of a captive specimen in Sri Lanka. Hump Nosed Vipers inhabit the Western Ghats of southern India and Sri Lanka. This snake lives in the leaf litter of evergreen forests, and feed on frogs, lizards, snakes, and small mammals. A 1998 Sri Lankan study found that 21% of 56 patients with proven hump-nosed viper bites developed oozing blood from the site of the bite and a prolonged clotting time; low fibrinogen levels; and increased fibrinogen degradation products in plasma. The envenomation can be complicated with a coagulopathy with excessive fibrinolysis the main abnormality (Premawardena et al. American Journal of Tropical Medicine and Hygiene 58: 821–823). Recently, Simpson and Norris (2007 Wilderness and Environmental Medicine, 18: 2-9) found that Hypnale does cause human deaths, often through renal failure sometime after the bite, and that bites from these snakes have often been confused as being from the saw-scaled viper, Echis carinatus.
The Mountain Viper, Ovophis monticola convictus (Stoliczka, 1870). Specimen from northern Thailand. As currently defined this is a wide spread race ranging from northwestern Thaialand southward to Malaysia, it is present in central Sumatra, and in southern China and Vietnam. Three other races are recognized and the species as a whole is poorly studied, which has lead Vogle (2006, Venomous Snakes of Asia) to suggest that it needs immediate work. This is a high altitude snake. It may reach a meter in length and it inhabits forest leaf litter.
