Isoperla eximia Zapekina­Dulkeit 1975

Teslenko, Valentina A. & Zhiltzova, Lidiya A., 2006, Nymphs of the genus Isoperla Banks (Plecoptera, Perlodidae) from the Eastern Palaearctic Region, Zootaxa 1130, pp. 1-33 : 8-9

Isoperla eximia Zapekina­Dulkeit 1975

( Figs. 15–21)

Description. Association with imago were carried out on mature nymphs from which the color pattern of the head and adult rudiments have been seen though exuviae's skin. Length of mature male nymph 8.3–9.5 mm, female 9.5–10.2 mm; cerci of male nymph 4.0– 4.5 mm; female 4.5–4.7 mm. General body color contrasting ( Fig.15), sharp dark longitudinal stripes and spots alternated with light ones. Clothing hairs on body surface dark and numerous, on abdomen light and scarcely visible.

Head with transverse occipital spinule row complete; dark ( Fig.15) with two pale “bean­shaped” spots between compound eyes, extending from occiput to anterior ocellus; interocellar area with small pale spot; occiput with pale diamond­shaped spot medially; elongate spot in front of anterior ocellus forming T­shaped area on frontoclypeus; labrum brown with two small pale spots laterally. Lacinia bidentate ( Fig. 16 ), triangular, inner margin with 4–5 stout setae and a few light thin setae; top of galea reaches to subapical tooth base. Mandible as in other species ( Fig. 17 ).

Thorax. Pronotum ( Fig. 15) fringed with short setae, occasional long hairs interspersed at upper and lower angles; posterior and anterior pronotal margins darken, lateral margins light; median pronotal line light and thin surrounded by a brown, lyre­shaped area; two rows of light longitudinal stripes with twisting margins and two dark­brown stripes occupy lateral pronotal fields. Meso­ and metanota with dark longitudinal bands following those of pronotum ( Fig. 15), complex color pattern medially, lateral margins light. Legs pale brown ( Fig. 18 ), with silky swimming hairs along outer margin of femur and tibia.

Abdomen. Abdominal terga patterned with alterating light and dark, longitudinal pigment bands ( Fig. 15). Posterior margin of abdominal terga with thick setae and long, thin setae. Intercalary bristles present. Cerci ( Figs. 19–21 ) pale brown without silky swimming setae; four apical cercal segments ( Fig. 21 ) with whorl of short and stout setae, and one long, ventral seta approximately one half length of the corresponding segment.

Material examined: Russia. Buryatiya: Margasan R., Zun­Murino R. Basin, 21.VII 1979, L. Zhiltzova, 3 nymphs; Baikal Lake, Babcha R., 28.VII 1979, L. Zhiltzova, 3 nymphs; Amur Region, Karapcha R., middle part, Khingan State Reserve, 2.X 1989, I. Ignatenko, 3 nymphs; Khabarovsky Region, Anyuy R., upstream, 30.VII 1996, T. Tiunova, 17 nymphs; Amgun R., 17. VI 1994, T. Tiunova, 7 nymphs; Petin Creek, Nemptu R. Basin, 21 VI 1998, V.Teslenko, 3 nymphs; Primorsky Region, Margaritovka R., 14.VI 1998, V. Teslenko, 1 nymph; Frolovka R., Partizanskaya R. Basin, 25.VI. 1984, V. Teslenko, 1 nymph; Sakhalin Isl.. Yuktolin R., 9.VIII 2001, T. Tiunova, 1 nymph; Kuril Isls. Iturup Isl., Dobroye Nachalo Bay, Bolshoy Creek, 15.IX 1999, V.Teslenko, 2 nymphs; China: Yuhualin Area, Antu Country, Jilin Prov., Chanbai Mnts., Erdaobaine R., 1770 m above sea level, 30.IV 1994, Eu. Makarchenko, 1 nymph.

Distribution. Russia: Sayan Mnts., Buryatiya, Baikal Lake Basin, Amur Region, Khabarovsky and Primorsky Regions, Sakhalin Island, Southern Kuril Islands; China; Mongolia.

Figures

FIGURES 16 – 21. Isoperla eximia: 16. Right maxilla, ventral. 17. Right mandible, ventral. 18. Right leg, dorsal. 19 – 21. Basal, medial, and apical sections of right cerci, lateral. Scale (mm): 18 = 0.51; 16, 17, 19 – 21 = 0.4.