Pteronarcyoidea, Newman, 1853

3.3. Pteronarcyoidea

3.3.1. † Cavoperlidae

† Cavoperla excavata Chen View in CoL forms the monotypic family † Cavoperlidae Chen View in CoL and is considered sister to Styloperlidae View in CoL due to similarities in wing venation, the loss of giant tibial spurs, and elongated basal cercomeres in the males ( Chen 2023b). However, no autapomorphies of Styloperlidae View in CoL are preserved, such as a dense setal brush on sternite nine in males, an X-shaped sclerotization of sternite ten, or modified tibial setae ( Chen 2023b, Uchida & Isobe 1989, Zwick 2000). Contrarily, the laterally expanded arolium is an autapomorphy of Pteronarcyidae View in CoL ( Uchida & Isobe 1989; Zwick 2000), and elongated basal cercomeres is an autapomorphy of Peltoperlinae View in CoL (Chen et al. 2025; Zwick 2000). However, as other apomorphies of all families within Pteronarcyoidea are not present in this species, its relationship to any of the extant families cannot be confidently resolved ( Chen 2023b).