Agkistrodon laticinctus

Agkistrodon laticinctus, commonly known as the broad-banded copperhead, is a venomous pit viper species, formerly considered a subspecies of Agkistrodon contortrix, which is found in the central United States, from Kansas, through Oklahoma and throughout central Texas.

Agkistrodon is from the Greek words ancistro which means “hook”, and odon meaning “tooth” referring to the snake’s fangs. The discrepancy between the spelling ancistro (correct) versus agkistro (incorrect), originates from a typographical error or misspelling in the original description of the genus published in 1799. The name laticinctus is from the Latin lati meaning “broad” or “wide”, and cinctus meaning a girdle, belt, or waistcloth, in reference to the broad bands of the dorsal pattern of the species, and relative to the contorted or twisted dorsal pattern of the eastern copperhead (Agkistrodon contortrix).

The standardized English name of Agkistrodon laticinctus is Broad-banded copperhead. As the Latin name, the English name emphasizes the broad bands that readily distinguishes this species from the eastern copperhead (Agkistrodon contortrix). Colloquial names for the broad-banded copperhead include: copperhead moccasin, copperhead snake, dry-land moccasin, highland moccasin, moccasin, rattlesnake pilot, red eye, Texas copperhead and thunder snake.

This form is typically a light tan in color, with darker brown, wide crossbands - which gives it its common name. The actual color varies, by locality, from a red-brown, to a gray-brown. It overlaps with the eastern copperhead, eastern copperhead (A. contortrix) in the southern reaches of its range, making specimens there difficult to distinguish, but generally A. contortrix has banding that narrows at the spine, creating hourglass shapes, whereas A. laticinctus has even bands. As juveniles, all species of Agkistrodon have a bright green-yellow color to their tail tips, believed to be used as a lure to attract prey items to approach within striking range. The color fades to a grey or brown at about a year of age.

Size: Adults typically range from 45‒75 cm (17.7‒29.5 in) in total body length, with a record individual of 94.6 cm (37.25 in) for the species. Agkistrodon laticinctus are sexually dimorphic, with males ranging slightly larger than females in total body length. One study measured 161 male and 119 female, adult specimens (>30 cm), and found 62.7% of the males ranged 50‒75 cm. (19.7‒29.5 in), and 76.5% of the females ranged 45‒65 cm (17.7‒25.6 in) in total body length. The same study found the tail length of males was only slightly longer than females, with tails ranging from 11‒17% (13.9) of total body length in males, and 11‒16% (13.3) in females, and Trans-Pecos populations averaging slightly longer tails, 15.3% for males and 14.6% for females. Copperheads tend to exhibit an east to west reduction in size, with the eastern copperhead (A. contortrix) averaging slightly larger in total body length than the broad-banded copperhead (A. laticinctus), and populations of A. laticinctus from Oklahoma and central Texas averaging slightly larger than those from the Trans-Pecos region and Mexico.

Scutellation: Agkistrodon laticinctus have nine large plates, symmetrically arranged on the crown of the head (two internasals, two prefrontals, one frontal, two supraoculars, two parietals): a character they share with all other species in the genus Agkistrodon, and which distinguishes Agkistrodon from the majority of pit vipers (Crotalinae), including all New World pit vipers except the genus Sistrurus (pigmy and massasauga rattlesnakes). A loreal scale is present in A. laticinctus and all other species in the genus except the cottonmouths (A. piscivorus and A. conanti). Postoculars and suboculars scales in Agkistrodon laticinctus tend to form one continuous row of 2‒6 scales, numbering 4 in about half of specimens. Supralabials range from 7‒10, numbering 8 in most specimens, and infralabials range from 8‒12, numbering 10 in most specimens. The dorsal body scales are keeled with paired apical pits. The keeling is strongest and most apparent on the vertebral scales, often becoming weaker and occasionally absent in the lateral and anterior regions. The number of midbody dorsal scale rows is typically 23 but can be 21 or 25 in a few individuals, except in populations from the Trans-Pecos region in which nearly half the specimens have 21 or 22 rows. Ventral scales: male range 138‒155, average 146.4 (Trans-Pecos populations averaging 149.3), female range138‒155, average 145.5 (Trans-Pecos average 147.3), and subcaudals: male range 42‒62 average 48 (Trans Pecos average 54), female range 40‒57 average 45 (Trans-Pecos average 50).

The broad-banded copperhead (A. laticinctus) is endemic to North America, where it occurs in the South Central states of Oklahoma and Texas in the USA, and the adjacent margins of the Mexican states of Chihuahua and Coahuila. It ranges from north-central Oklahoma, south to the Edwards Plateau in Texas, and west into southern counties of the Trans-Pecos region of Texas, including Brewster, Jeff Davis, Pecos, Presidio, and Terrell counties. Much of its distribution (and the zone of hybridization) is situated in something of a transition zone between the Eastern Temperate Forests of the US and the Great Plains and Chihuahua Desert to the west.

In Mexico it is known only from the states of Chihuahua and Coahuila. Copperheads were anticipated to occur in Mexico for several decades before verified records were confirmed from the remote regions south of Big Bend as recently as 1986. In Chihuahua all records are from riparian areas along the Rio Grande and adjacent canyons in the municipality of Manuel Benavides. In Coahuila it has been reported from several localities deeper in the interior including the Sierra del Burro, Sierra del Carmen, and Sierra Jardín, in the municipalities of Acuña, Müzquiz, Ocampo, and Zaragrza.