Chagasia is one of the three mosquito genera in the subfamily Anophelinae. The other two genera are Anopheles Meigen (nearly worldwide distribution) and Bironella Theobald (Australia only). The subfamily consists of five species in the Neotropical region. These include C. ablusa Harbach, C. bathana Dyar, C. bonneae Root, C. fajardi Lutz and C. rozeboomi Causey, Deane & Deane.

Bironella appears to be the sister taxon to Anopheles, with Chagasia forming the outgroup in this subfamily.

The species Chagasia bathana has 8 chromosomes and males are heterogametic with one long X chromosome and one short Y chromosome.^{[1] [2]}