The thoracic pleura are broadly reddish-brown, progressively darkening to black near the coxa and posterior edge.

Connexivum exposed lateral to wings; connexival segments 3–7 with apicolateral spines, that on 3 very small; that on 7 smaller than that on 6.

[4] The species has been recorded in Mexico, specifically in Veracruz (Orizaba and Misantla), as well as in Guatemala (Senahu and Cerro Zunil).

[4] Schaefer and Mitchell (1983) noted that the food plant record previously attributed to this species by Aldrich and Blum (1978) is likely misidentified and should instead correspond to Pachylis laticornis.

[3] The reason Thasus acutangulus is also referred to as Pachylis acutangula stems from the historical difficulty in distinguishing these two genera.

Both Pachylis and Thasus share nearly identical diagnostic characteristics, including robust black bodies, expanded antennomeres, and metatibiae (tibiae of the hind legs).

However, recent phylogenetic studies have found this trait to be homoplasic, meaning it evolved independently and does not reliably differentiate the two genera.