[3] At least two of these specimens do not belong to any species of Tersomius and were reassigned by Maddin et al. (2013), which has led some authors to consider it as a potential "wastebasket taxon.

[5] A second species of Tersomius, T. mosesi, was named by Olson (1970) for Amos Moses, the property owner of the land in Oklahoma where the material was collected from.

A third species of Tersomius, T. dolesensis, was named by Anderson & Bolt (2013) from the Richards Spur locality in Oklahoma.

The most recent revision of the genus is that of Schoch & Milner (2014), who list a combination of seven features and two plesiomorphies: (1) nearly circular outline of skull with curved maxilla; (2) prefrontal and postfrontal separated; (3) preorbital region equal to skull table in length; (4) internarial fenestra present; (5) teeth variably monocuspid and bicuspid; (6) vomer with both medial and lateral fangs; (7) palatine lacking denticles; (8) long supratemporal; (9) postparietal longer than tabular.

Tersomius texensis is usually utilized as the representative of the genus in most analyses in which it is recovered as being closely related to Micropholis and Pasawioops, forming the Micropholidae.