Agkistrodon

Agkistrodon is a genus of venomous pit vipers found in North America from the United States south to northern Costa Rica. Three species are currently recognized, all of them polytypic and closely related. Common names include: cottonmouth, copperheads, cantils.

Name origin

The name Agkistrodon comes from the Greek words agkistron (ἄγκιστρον, 'fishhook', with the irregular transliteration gk rather than the usual nk) and odous (ὁδοὐς, 'tooth,' from the stem ὁδόντ-) and is likely a reference to the fangs.

Description

Members of this genus have a number of features in common. All species have a relatively broad head with short fangs. A loreal scale is present, except in A. piscivorus. There are usually nine large symmetrical platelike scales on the crown of the head, but in all species these are often irregularly fragmented or have sutures, especially in A. bilineatus. All have a sharply defined canthus rostralis and a vertically elliptical pupil. There are 6-10 (usually 8) supralabial scales and 8-13 (usually 10-11) sublabials. The dorsal scales are mostly keeled and at midbody number 21-25 (usually 23), while A. piscivorus has 23-27 (usually 25). There are 127-157 ventral scales and 36-71 subcaudals. Of the latter, some may be divided. The anal scale is single. All have a color pattern of 10-20 dark crossbands on a lighter ground color, although sometimes the crossbands are staggered as half bands on either side of the body.