Adults of M. barbouri generally grow to 30–40 cm (11¾-15¾ inches) in total length (including tail), with a maximum recorded total length of 51.0 cm (20 in). The species is terrestrial and moderately stout.[5]
The color pattern consists of a blackish ground color, overlaid with a vague dorsal zig-zag stripe that extends down the flanks, which looks like a series of triangular markings. The skin between the scales is rust-colored, as are the sides of the head.[6]
The species M. barbouri is classified as Endangered (EN) on the IUCNRed List of Threatened Species with the following criteria: B1ab(iii) (v3.1, 2001).[1] A species is listed as such when the best available evidence indicates that the geographic range, in the form of extent of occurrence, is estimated to be less than 5,000 km² (1,930 mi²), estimates indicate the population is severely fragmented or known to exist at no more than five locations, and a continuing decline has been observed, inferred or projected in the area, extent and/or quality of habitat. It is therefore considered to be facing a very high risk of extinction in the wild. The population trend is down. Year assessed: 2007.[8]
^ abMcDiarmid RW, Campbell JA, Touré T (1999). Snake Species of the World: A Taxonomic and Geographic Reference, Volume 1. Washington, District of Columbia: Herpetologists' League. 511 pp. ISBN1-893777-00-6 (series). ISBN1-893777-01-4 (volume).
Dunn ER (1919). "Two New Crotaline Snakes from Western Mexico". Proceedings of the Biological Society of Washington32: 213-216. (Lachesis barbouri, new species, pp. 213–214).