four main endothiodont genera, "endothiodon", "esoterodon", "endogomphodon", and "emydochampsa", were originally separated under the subfamily endothiodontinae. when "e. uniseries" was first discovered it was thought to be the type species of the genus "esoterodon". in 1964 cox sorted out all of the taxa of endothiodonts and found that the characters originally separating the four genera were not valid. the four genera were grouped into the one genus "endothiodon". with originally nine species of "endothiodon", cox was able to narrow it down to just three species based on skull size and robustness of the lower jaw. a fourth species of "endothiodon" was found in india that was unique compared to the other three species. it had a small size, a single longitudinal ridge on the snout, an elongated pineal foramen situated on a low boss located midway on the intertemporal bar, and a slender dentary symphysis. some of these characteristics such as the shape of the pineal foramen and the presence of three longitudinal ridges were thought to be distinguishing characteristics of the genera as a whole, but are now only valid at specific level. another new species was collected in tanzania in 1963 and is under description. it is distinguished from all other specimens based on the lack of a pineal boss and the presence of a pair of tusks lateral to the tooth row.