Boreus reductus Carpenter, 1933
Diagnosis: This species is dark brown and 1.9 to 2.4 mm long (males), and 2.8 to 3.1 mm (females). Specimens preserved in alcohol are 3.3 to 3.9 mm long (males), and 4.8 mm (females). The ratio of the maxillary-labial complex to rostrum is 0.9. There are no long setae on the pronotum. Male wings are abruptly narrowed at mid-length, with 16 to 19 forewing spines and three hindwing spines. Females have very short wing pads – the forewing pads do not overlap the hindwing pads. Male eighth tergum and sternum not fused. Male dorsal hood only about ¼ width of ninth segment, but bearing a tiny medial septum. Male ninth sternite sharply narrowed in apical half and apically rounded.
Distribution – Geographical: This species is found over much of the Great Basin and drier interior regions of western U.S.A. and Canada, from British Columbia south to Utah and Nevada.
Distribution – Temporal: Adults have been collected from 27 November until 22 March, with one isolated record from Nevada on 25 May.
Ecology: This species has been collected on the cold sagebrush desert some distance from any apparent water or mosses. Its host moss is still unknown.
Biology: Nothing is known of immature stages or life history.
Notes: There are several unique morphological features of this species. The females have very short wing scales. This is the only North American species in which males do not have laterally fused eighth tergites and sternites.
Carpenter, F.M. 1933. A new Boreus from British Columbia (Mecoptera). Canadian Entomologist. 65:94-95.
Penny, N.D. 1977. A systematic study of the Family Boreidae (Mecoptera). University of Kansas Science Bulletin, 51(5)141-217.