. Adults of
A. melanocephalus typically grow to in length (including tail), but can grow to a maximum length of . The body is muscular with a flattened profile, while the tail tapers to a thin point. The top of the head is covered by large symmetrical scales. The
dorsal scales, which are smooth and
glossy, number 50-65 rows at midbody, while 315-355
ventral scales occur. The tail has 60-75 mainly single
subcaudal scales and the
anal scale is single. The posterior subcaudals tend to be divided, often irregularly. The color pattern consists of shades of black, dark grey, brown, gold, and cream arranged in a banded or brindled pattern. The belly is light-colored, flecked with darker spots. The head is shiny black that also extends down the neck and throat for several inches. ==Distribution and habitat==