Haematochiton carbonarius

Haematochiton carbonarius is a small black species of pleasing fungus beetle (family Erotylidae) from Central and North America. Among its family, the genus Haematochiton is placed in subfamily Tritominae, or – in taxonomic arrangements that prefer a more comprehensive subfamily Erotylinae – in tribe Tritomini of the Erotylinae.

Whether the small and little-studied genus Haematochiton is distinct from its close relative, the hugely successful Mycotretus radiation, remains to be determined. When Henry S. Gorham first named the present species in 1888, he placed into a monotypic genus Scaeother due to its distinctive dull coal-black coloration, not recognizing the traits that linked it to Haematochiton elateroides (which he described in the same work) and Mycotretus (which are usually boldly patterned or brightly colored).

Charles F.A.Schäffer in 1915 believed he could distinguish two species in these beetles, and named his "new" species Scaeother opacus; the supposed differences are, however, within normal variation in this species – more or less dense punctuation on the upperside, and a rounded or keel-shaped pronotal bulge –, and no subspecies are rcognized today.

Description

Haematochiton carbonarius are small beetles, about one-fifth of an inch long and slightly less than half as wide (around 4.5-4.65 mm long and 2.2 mm wide) as adults. They are black all over except for the tarsi, palps, and the five basal antenna segments, which are brown. Most of the carapace is covered in microscopic reticulated relief that makes it look matte. The body is elliptical, with a smoothly rounded head and a slightly more pointed wingtip.

Head

The head is elongate-oval and well visible from above; it lacks file-like structures for stridulation at least in females, and has no constriction between the rather small compound eyes.