[1][2] Hapsidopareion was named in 1973 by American paleontologist Eleanor Daly based on material collected from the early Permian South Grandfield locality in southwestern Oklahoma.

[3] Because all specimens of H. lepton are notably smaller than those of L. pricei, and a number of anatomical differences are likely ontogenetically variable (e.g., contact between neural arch and centrum), some researchers considered that the former maybe represent a juvenile of the latter, but recent workers have maintained the separation of these taxa.

[3][4] Using high-resolution micro-CT scans of three skulls of the coeval Hapsidopareion, Jenkins et al. (2025) identified that many of the characters used to distinguish Llistrofus from it are shared by both taxa.

Due to its larger size, they identified Llistrofus as representing a more mature ontogenetic stage of Hapsidopareion, and argued that the former should be regarded as a junior synonym of the latter.

The results of their phylogenetic analyses are displayed in the cladogram below, where they found recumbirostrans to be a clade along the amniote stem:[5] Limnoscelis Captorhinidae Protorothyris Amniota Pantylus Hapsidopareion (including Llistrofus) Odonterpetidae Molgophidae Brachystelechidae Huskerpeton Proxilodon Gymnarthridae Rhynchonkidae Ostodolepididae