the "mastotermes electromexicus" soldier is known from only a portion of the head and mandible. the head is estimated to have been wide with long hairs on each side of the head below the antennae. the mandibles are gently curved inwards, in contrast to those of "m. darwiniensis" which are a more curved and having a hooked appearance. the imago is known from a partial head, thorax, and hind wings. the wide head of the imago is wider than seen in "m. darwiniensis" with smaller eyes and ocelli which do not touch the compound eyes. the nymphs are known from a series of partial fossils in thirteen pieces of amber and representing several different instars. the heads vary between , showing a larger range of size then those of "m. darwiniensis". the antennae have approximately twenty four segments, flagellomeres, and the legs host a number of bristles and several short spines.