Rhithrogena sibirica Brodsky 1930

Tiunova, Tatiana M., 2010, A new species of Rhithrogena Eaton, 1881 from the Far East of Russia with notes on this genus in this area (Ephemeroptera: Heptageniidae), Zootaxa 2639, pp. 1-18 : 13-16

Rhithrogena sibirica Brodsky 1930

( Figs. 60–77 )

Material examined. RUSSIA. Yakutiya: Lena River Basin, Dabai River, near Dabai Village, 2.VIII 1987, V Bogatov, 1 male imago; Aldan River Basin, Chulman River, upper Nerjungri City, 25.VII 2006, T Tiunova, 4 larvae; Magadanskaya Oblast’: Tauj River, middle part, 11.VII 2001, S Kocharina, 1 male imago; Tauj River Basin, Kava River, 9.VII. 2001, S Kocharina, 1 male imago; same place, 19.VII 2001, 1 male imago; same place, 30.VII 2001, 3 male imagines; Tauj River Basin, Chelomdzha River, 14.VII 2001, S Kocharina, 3 male imagines. Chitinskaya Oblast’: Selenga River Basin, Kaban’ya River, about 45 km upper mouth, 26.IV 2009, N Bazova, 1 larvae. Amurskaya Oblast’: Bureya River, near Novo-Burejsk Village, 25.VI 2004, T Tiunova, 1 male imago; Zeya River, near Krasnoyarovo village, 13.VI 2004, T Tiunova, 3 male imagines; same place, 24.VI 2004, 9 male imagines; Zeya River, near Zeya City, 20.VI 2004, T Tiunova, 30 male, 2 female imagines; Zeya Hydro-Electric Power Station Basin, Giljuj River, middle part, 19.VI 2004, T Tiunova, 9 male imagines; Zeya Hydro-Electric Power Station Basin, small stream 2 km below mountain Zolotaya Gora, 20.VI 2004, T Tiunova, 1 male imago. Khabarovskiy Kray: Amgun River Basin, Suluk River, about 10 km below Suluk Village, 16.VI 1994, T Tiunova, 9 larvae; Amgun River, near Dopsikan mountain, 24.VI 1994, T Tiunova, 23 male, 4 female imagines, 18 male, 6 female subimago, 5 larvae; Amgun River, near Postishevo Village, 28.VI 2004, T Tiunova, 4 male, 1 female imago, 1 male, 1 female subimago, 3 larvae; Ussuri River Basin, Chuken River, mouth, tributary of Chor River, 10.VI 1995, T Tiunova, 7 larvae; Sukpaj River, near Sukpaj Village, tributary of Chor River, 22.VI 1998, T Tiunova, 8 male imagines; Chor River, near Srednehorsky Village, 13.VI 1995, 4 male imagines; Chor River, 1.5 km below Gvasjugi Village, 14.VI 1995, T Tiunova, 30 male imagines; Chor River, near Kafe Village, 15.VI 1995, T Tiunova, 2 male, 2 female imagines (reared from larvae); Amur River, near Tsimmermanovka Village, 21.VI 2000, T Tiunova, 27 male, 3 female imagines; Mutii River, tributary Yaj River, below motor-car bridge, line Khabarovsk – De-Kastri, 30.VI 2005, T Tiunova, 5 male imagines; Bureya River Basin, Chegdomyn River, near Chegdomyn Village, 13.VII 2003, T Tiunova, 3 male imagines, 7 larvae; Nimakan River, mouth, 15.VII 2003, T Tiunova, 1 male imago; Niman River, 1.5 km upper mouth Nimakan River, 15.VII 2003, T Tiunova, 4 male imagines; Priokhot’e, Khetana River, 7 km upper mouth, tributary of Ul’ya River, 16.VIII 1985, V Zherikhin, 1 male imago; Kuhtuj River, about 10 km upper mouth, 10–12.VIII 1998, T Tiunova, 7 larvae; same place, 28–30.VI 1999, T Tiunova, 2 male, 3 female imagines, 5 larvae; Okhota River, about 6 km upper mouth, 1–5.VIII 1998, T Tiunova, 13 larvae; same place, 25–27.VI 1999, T Tiunova, 5 larvae; Okhota River, about 30 km upper mouth, 6–8.VIII 1998, T Tiunova, 4 male, 5 female imagines (reared from larvae); Lantar River, 2.5 km upper mouth, 28.VII 1999, T Tiunova, 1 male, 3 female imagines, 1 male, 1 female subimago; Uda River, about 5 km upper mouth, 13.VIII 2000, T Tiunova, 3 male imagines; Uda River, about 140 km upper mouth, 15– 20.VIII 2000, T Tiunova, 5 male imagines; Tatar strait Basin, Tumnin River, near mouth Tun’ River, 18– 19.VII 1997, T Tiunova, 2 male imagines; Tumnin River, near Gapanki mountain, 29–30.VI 1997, T Tiunova, 3 male, 2 female imagines; Aldan River Basin, Maya River, 1 km below Nel’kan village, 5–8.VIII 1999, T Tiunova, 1 male imago (reared from larvae), 6 male imagines. Primorskiy Kray: Armu River, upper part, tributary Bolshaya Ussurka River, 15.VI 1990, T Tiunova, 1 male imago; Bolshaya Ussurka River, 1,5 km upper mouth Daljnaya River, 23.VI 1990, T Tiunova, 1 male imago; Tuschnaya River, mouth, tributary Bikin River, 19.VI 1998, T Tiunova, 1 male imago.

Description. Male imago (in alcohol). Dimensions: length (mm): body 8.1–12.0; forewings 9.0–12.0; cerci 16.0–27.0. Thorax: pronotum brown, mesonotum dark brown; scutellum dark brown with a white cross-sectional strip; sublateroscutum white ( Fig. 60 ); metanotum and metasternum dark brown. Length (mm) of foreleg segments: femora 1.7–2.5; tibia 1.9–2.6; tarsal segments 0.2–0.3, 0.9–1.5, 0.9–1.4, 0.6–1.1, 0.4– 0.6. Wings hyaline, veins from dark brown to brown. Abdomen: terga 2–7 dark brown with the lateral area darker, translucent; terga 2 with a pair of large whitish spots at the distal margin; terga 3–8 with a pair of light spots at the distal margin and a pair of small specks in the middle area; terga 8–9 opaque. Sterna translucent, dark brown with a lighter base and small white specks that are poorly expressed. Forceps dark brown; middle area of styliger plate light brown ( Fig. 61 ). Penis lobes brownish, inner margin darker, strongly supported edge of the styliger plate; penis lobes long with widely placed top portions, with a middle portion expanded and with a long ( Figs. 62–63 ), sharp shoot at the base ( Fig. 63–64 ); titillators absent. Cerci: proximal third brown, distal portion from light brown to yellow.

Female imago. Dimensions: length (mm): 7.0–9.7; forewings 9.0–11.3; cerci 8.8–12.0. Thorax: pronotum brown with a light spot in the distal area; mesonotum brown; medioscutum and submedioscutum light brown; anteronotal protuberance dark brown, scutellum dark brown with a white top portion, lateroparapsidal suture light brown, lighter than the submedioscutum. Abdomen: terga and sterna colored as in males; sternum 7 dark brown; sterna 2–5 with a pair of oblique, light colored strokes in the distal area and a pair of small, light specks in the middle area. Cerci: brown at the base and yellowish at the tip.

Male subimago. Thorax: pronotum and mesonotum white; medioscutum and submedioscutum light brown; anteronotal protuberance and lateroparapsidal suture dark brown; scutellum, parascutellum and posterior scutal protuberance light brown. Forelegs brown, middle and hind legs yellow, tinged with brownish color; femora of all legs with a dark longitudinal spot in the middle area. Wings light brown, translucent.

Abdomen: terga 1–9 dark brown, opaque; terga 2–6 with a pair of light oval specks near the distal margin and a pair of small light round spots in the middle area; terga 7–8 with a pair of small light specks. Sterna 1–6 brown, 7–9 dark brown; sterna 2–7 with a pair of oblique light colored strokes in the distal area and a pair of light colored, round specks in the middle area. Cerci brown, uniformly colored.

Mature larva. Dimensions: length (mm): body 8.0–10.2, cerci 6.5–8.2. Head: forehead brown ( Fig. 65 ). Maxilla with 8 comb-shaped setae at the apical margin ( Fig. 68 ); labrum width approximately 4.4 times longer than the length ( Fig. 66 ). Thorax: pronotum brown with lighter anterior and posterior margins; mesonotum brown; at the base of the wing pads, there are two small curved strips. Legs brown; femurs of all legs may or may not have a dark, indistinct spot in the middle of the light central area; setae on the dorsal surface of forefemora of the identical form, extended with a rounded apex ( Fig. 73 ). Claws of fore- and middle legs with 2 subapical denticles ( Figs. 75–76 ). Length (mm) of leg segments are as follows. Foreleg: femur 1.3–1.9, tibia 1.4–1.7, tarsus 0.6–0.7; middle leg: femur 1.4–2.1, tibia 1.3–1.6, tarsus 0.4–0.5; hind leg: femur 1.7–2.6, tibia 1.1–1.9, tarsus 0.4–0.5. Abdomen: terga brown, usually uniformly; terga 3–6 with a pair of small dark stripes in the middle area; central portion of the posterior margin of terga 5 having long and pointed teeth of uniform size ( Fig. 77 ). Sterna brown; posteromedian emargination on sterna 9 poorly expressed ( Fig. 74 ). Gills white, often with the inner half of the tergalius being dark pink or grayish-brown; gill I large, with an even outer margin ( Fig. 69 ); gills III–IV with a rounded ledge on the posterior margin ( Figs. 70–71 ); gill VII broadened in the middle area ( Fig. 72 ). Cerci yellowish or whitish.

Distribution and biology. Rhithrogena sibirica is an East Palaearctic species that is distributed in East Siberia ( Kluge 1980), including southern Yakutiya (Tiunova et al. 2009), Magadanskaya Oblast’( Zasypkina 1980; Arefina et al. 2003), Kamchatka ( Levanidova 1972), Altai ( Brodsky 1930; Beketov 2005), the south of Russian Far East ( Tshernova et al. 1986; Kluge 1997; Tiunova 2007a, 2008, 2009, Tiunova & Potikha 2005) and Mongolia ( Bajkova & Varychanova 1978; Braasch 1979, 1986; Landa & Soldán 1983; Soldán et al. 2009).

Larvae of this species were found in stones, gravel and pebbles in rivers of different types.

Figures

FIGURES 60 – 64. Rhithrogena sibirica, male imago: 60. Mesonotum, dorsal. 61. Genitalia, ventral. 62. Penis, ventral. 63. Penis, dorsal. 64. Penis, lateral. Scale (mm): 60 = 1.0; 61 – 64 = 0.5.

FIGURES 65 – 77. Rhithrogena sibirica, larva: 65. Head, dorsal. 66. Labrum, dorsal. 67. Teeth of left mandible, dorsal. 68. Comb-shaped setae of the maxilla. 69. Gill I. 70. Gill III. 71. Gill IV. 72. Gill VII. 73. Setae on the dorsal surface of fore femora. 74. Abdominal sternum 9 (female). 75. Tarsal claw of fore leg. 76. Tarsal claw of middle leg. 77. Posterior margin of terga 5. Scale (mm): 65,69 = 1.0; 66,74 = 0.2; 67 – 68,75 – 76 = 0.01; 70 – 72 = 0.5; 73,77 = 0.05.