Prostoia besametsa (Ricker) Figs 1-8, 41

Nemoura (Prostoia) besametsa Ricker, 1952: 48. Holotype ♂ (INHS), Vedder Crossing, British Columbia, Canada

Nemoura glabra (in part) Claassen, 1923: 281

Nemoura glabra (in part) Needham & Claassen, 1925: 202. Syn. Illies, 1966: 221

Prostoia besametsa: Illies 1966: 220

Prostoia besametsa: Zwick 1973: 345

Prostoia besametsa: Baumann 1975: 27

Prostoia besametsa: Baumann et al. 1977: 38

Material examined

(Suppl. material 1).

Distribution.

Canada: AB, BC (DeWalt et al. 2013), NT (Stewart and Oswood 2006), YK (Stewart and Ricker 1997); USA: AK (Stewart and Oswood 2006), CA, CO, ID, MT, NM, NV, OR, SD, UT, WA, WY (DeWalt et al. 2013), NE (New state record).

Remarks.

Prostoia besametsa, Prostoia completa and Prostoia ozarkensis sp. n. appear to form a species group based on structural similarities of the male ventral sclerite and lateral arms of the dorsal sclerite, and the female subgenital plate. The Black Hills region of eastern Wyoming and western South Dakota, plus the Sand Hills region of northwestern Nebraska, mark the eastern edge of this widespread western Nearctic species in the USA (Fig. 41), and well distant from the closest distribution point of Prostoia completa (Fig. 41) and Prostoia ozarkensis sp. n. (Fig. 42) (Huntsman et al. 1999, DeWalt et al. 2013). Prostoia besametsa is typically found in greatest numbers in large streams and small rivers.