"mastotermes electromexicus" is known from a series of fourteen fossil insects which are inclusions in transparent chunks of mexican amber. the amber specimens, a soldier, an imago and twelve nymphs are currently housed in the fossil collection of the university of california, berkeley in berkeley, california. the holotype fossil is composed of a partial soldier caste individual. mexican amber is recovered from fossil bearing rocks in the simojovel region of chiapas, mexico. the amber dates from between 22.5 million years old, for the youngest sediments of the balumtun sandstone, and 26 million years old la quinta formation. this age range straddles the boundary between the late oligocene and early miocene and is complicated by both formations being secondary deposits for the amber, the age range is only the youngest that it might be. the holotype was first studied by entomologists kumar krishna of the american museum of natural history and alfred emerson of the university of chicago. krishna and emerson's 1983 type description of the species was published in the natural sciences journal "american museum novitates". the specific epithet "electromexicus" was coined from the greek word "ēlektron" meaning "amber" combined with mexico as a reference to the nature of the preservation and the country of the type locality.