Known gill configurations in Rhyacophila and Himalopsyche kuldschensis groups, shown as a latero-apical depiction of the gill filaments on the side of larval abdominal segments. Grey box indicates R. vulgaris group species; dashed line segregates the representative of Himalopsyche. — * For the purpose of this manuscript we define gills of single unbranched filaments as “simple” gills. — ** For the purpose of this manuscript we define “complex” gills as those gills that exhibit a branching pattern; + sensu Döhler (1950); sensu Giersch 2002; ° sensu Giersch & Wissemann 2012; § sensu Lepneva (1970); $ sensu Hjalmarsson et al. (2018).