Mayfly Species Parameletus chelifer (Gray Drakes)

Source: Two new species of Parameletus Bengtsson, 1908 (Ephemeroptera: Siphlonuridae), and notes on other species from the Far East of Russia

Male imago. Dimensions: length (mm): body 12.8 – 15.0; fore wings 12.0 – 13.1; cerci 17.2 – 22.4. Total color of living imago dark brown. Head: upper portion of eyes light brown or light gray. Thorax: medioscutum and submedioscutum brown; sublateroscutum and posterior scutal protuberance dark brown (Fig. 23); mesosternum from dark brown to dark. Fore legs brown, middle and hind legs from light brown to yellowish. Length (mm) of foreleg segments: femora 2.7 – 3.1; tibia 2.4 – 2.7; tarsal segments 1.4 – 1.7, 1.5 – 1.9, 1.6 – 1.9, 1.3 – 1.6, 0.8 – 1.0. The ratio of length to the maximal width for fore wing — 2.40 (Fig. 20), hind wing — 1.47 (Fig. 21). Abdomen: terga 2 – 9 opaque with pair of elongated dark brown spots in middle part; lateral part of posterior margins darkened. Sterna brown, sterna 7 – 9 dark brown, opaque. Forceps brown, styliger plate dark brown. Middle part of posterior margin of styliger protuberant, wavy (Fig. 22). Penis lobes from dark brown up to black. External penis lobes wide with rounded apices; inner lobes straight, narrowed toward apex, with furcated top (Figs. 16 – 17). Ventral processes dark brown, pointed, reach ½ of length of external lobes (Figs. 17, 19). Cerci brown, with base darker.