Micrurus diastema alienus
Yucatán, Mexico. June 26, 2016
‘Variable’ is appropriate as there currently seven recognized subspecies of this coral snake, many of which are difficult to tell apart. However, Blaney & Blaney 1979 indicated that at least two subspecies (alienus and sapperi) could be differentiated by the number of black rings. The northern subspecies alienus has fewer black rings (12 avg), and the red rings are much wider. The southern sapperi has more black rings (avg 18), and the red rings are narrower. Of course, one has to believe in subspecies, and for the moment, I’ll go with the recognized differences.
See: Blaney, Richard M. and Patricia Kimmich Blaney 1979. Variation in the Coral Snake, Micrurus diastema, in Quintana Roo, México. Herpetologica 35 (3): 276-278
My Flickr album for Yucatán 2016 is here.
HerpMapper records for this species are here.