Distribution

From Mexico, southward through Central America to Panama. See link "Distribution" at the top of the page for detailed informations.

Biology

Usually live in mesic habitats ranging from rainforest to cloud forest. M. occiduus found seasonally in dry pine and dry pine/oak forests. Found from sea level up to 1,800 or 2,000 m.  M. occiduus and M. olmec are restricted to upland habitats, whereas M. nummifer and M. mexicanus are mostly found above 1,000 m but may also be seen almost at sea level.
All members are extremely stout-bodied and ground-dwelling, Large head with broadly rounded snout and small eyes. Length up to 1 m.
Basic colouring most often grey-brown or reddish-brown, sometimes also black. Dark post-ocular stripe, zigzag pattern along the dorsal part of the body, smaller lateral blotches. Lowland populations may be active during the day and the night, whereas upland populations tend to be active during the day only.
Juveniles of all species have a yellow tail tip (lure).

Danger

These snakes usually retain their grip after striking and sometimes inject more venom by a chewing action.

The largest species, A. nummifer, is potentially the most dangerous in this genus, but it seems that bites occur only rarely. A. nummifer bites are believed to have claimed several lives (Jutzy et al. 1953, Sass 1979).

Literature (biological)

Campbell and Lamar 2004, Campbell et al. 2019, Tepos-Ramirez et al. 2023