Rauserodes epiproctalis (Zwick, 1997)

Rauserella epiproctalis: Zwick, 1997, Ephemeroptera & Plecoptera, Biology-Ecology-Systematics: 489–496.

Rauserodes epiproctalis: Zwick, 1999, Aquatic Insects, 21 (3):168.

Male: Micropterous, forewing length ca. 3 mm, hindwing length 3 mm, body length 14 mm. General color reddish brown to brown (Fig. 12). Head mostly yellowish to light brown, laterally frontoclypeus brown and median occiput with several dark brown spots. Antennae and palpi dark brown. Pronotum disc dark brown, with a yellowish medial longitudinal stripe, with several dispersed yellow spots near its lateral margin (Fig. 13). Legs yellowish to brown; wings smoky gray, bearing fine hairs on the surface, pores on veins and area around anal veins larger than the others; veins brown and thick (Fig. 14). Abdomen brown or dark brown, slightly sclerotized, bearing yellowish long hairs; terga 1–6 with a large triangle dark spot medially; terga 1–9 with proximal dark spots and small, round lateral sclerites (Figs. 12, 15, 16).

Tergum 7–9 without median dark spots (Fig. 15). Tergum 8 with a patch of developed median basiconica sensilla (Fig. 15). Tergum 9 posteriorly membranous, bearing sensilla basiconica of two types, separate or connected by irregular sclerites on the anterior or posterior of the membranous area (Fig. 17). Tergum 10 with a pair of dark lateral spots, and a dark longitudinal median band, sometimes lacking not; posterior margin heavily sclerotized, curved upward and fully covered with sensilla basiconica (Fig. 18). Paraprocts triangle, inner margin membranous and bearing fine spines, sclerotized apically and basally (Fig. 19).

The membranous epiproct divided into two lobes: the basal lobe swollen, dorsally with a pair of short process near tergum 10, and a pair of fingerlike process extended from the apex; apical lobe short, approximately rhombic in shape, blunt apically (Fig. 20). Aedeagus (Fig. 21) a membranous tube with narrow base, with a subterminal ring-like swelling which is roughened by cuticular asperities on its outer face; apex heart-shaped and smooth, as described by Zwick (1997).

Female: Macropterous, forewing length 21 mm, hindwing length 18 mm, body length 19 mm. Coloration of head, thorax dark brown to black (Fig. 22). Area between hind ocelli and median occiput with a yellow spot; occiput with lateral rugosities; palpi light brown. Pronotum disc dark brown, rugosities present laterally, and a yellowish longitudinal band among the centerline (Fig. 23). Legs brown. Wings smoky gray and translucence; veins dark brown (Fig. 24). Some individuals have more cross veins between subcosta and radius veins of forewing, or additional branches of the anal veins of hindwing (Fig. 25). Abdomen brown; subgenital plate short and sclerotized, variable; median posterior margin heavily sclerotized and bilobate (Fig. 26).

Egg: See Zwick (1997). No mature eggs were present in the below material.

Nymph: Unknown.

Material examined: 10 ♂♂, 4 ♀♀ (ICYZU), China, Qinghai Province, Haibei Tibetan Autonomous Prefecture, Menyuan Hui Autonomous County, Liuhuanggou, 3720 m, 101°21'16"E, 37°46'22"N (UTM: 47 N 707365 4183215), 2019-VIII-14, leg. Wang Lu-Yu, Chen Zhen-Ning ; 4♂♂, 2 ♀♀ (CAF), Liuhuanggou, 101°18'8"E, 37°41'56"N (UTM: 47 N 702967 4174901), 2019-VII-29, leg. Kong Xiang-Bo, Fang Jia-Xing, He Yun-Chuan .

Distribution: China (Qinghai Province).

Remarks. This species apparently inhabits pristine cool valley streams and nymphs occur under mats of instream vegetation and under rocks (Fig. 27).