Agkistrodon russeolus, commonly called the Yucatecan cantil,[3] is a venomous pit viper species[4] endemic to the Yucatán Peninsula in Mexico and northern Belize.

The head is clearly marked on either side with two longitudinal light lines: the upper one is narrow and may be broken behind to the eye, while the lower one is wider and separated from the commissure by a dark band.

"[5]: 328 p.  The majority of records are from the semi-arid northern regions of the peninsula in the state of Yucatán, Mexico.

However, several additional records are scattered in the south at various isolated localities in the Mexican states of Campeche, Tabasco, the vicinity of the Quintana Roo and Belize border, and northern Guatemala.

[3]: 60 p. [6]: 61 p. [7]: 399 p. [8] A number of reptiles from the Yucatán Peninsula fit this pattern of distribution, with continuous and unbroken records in the north, and several isolated and disjunct populations in the south.