Isoperla asiatica Raušer 1968

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 : 5-8

Isoperla asiatica Raušer 1968

( Figs. 8–14)

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 skins. Length of mature male nymph 10.2–10.5 mm, female 11.0– 12.3 mm; cerci of male nymph 5.0– 5.7; female 5.0– 6.2 mm. General body color pale with extensive brown pattern. Clothing hairs dark and thick.

Head with occipital transverse spinule row interrupted medially; brown ( Fig. 8), narrow, pigmented band between antennal bases extended backward to lateral ocelli, connecting them to anterior ocellus; interocellar area pale; two rectangular, pale areas mesad of eyes; occiput yellowish with indistinct brownish area medially. Frontoclypeus slightly brownish along lateral margins; labrum yellowish, slightly darker anteriorly. Lacinia ( Fig. 9 ) bidentate and quadrate in shape, with 10 large dark setae below the subapical tooth, several thinner setae at its mesobasal margin. Maxillary palp long, its fourth segment longer than others; top of galea reaches to subapical tooth base. Mandible ( Fig. 10 ) with six unserrated teeth and two rows of setae: first setal row extends from the base of the first tooth; the second setal row extends from the base of the fourth tooth.

Thorax. Pronotum oval ( Fig. 8); anterior and posterior margins darken medially; fringed with short, thick setae; central large, pale spot surrounded by dark pigment; lateral margins pale. Meso­ and metanotum ( Fig. 8) with complicated patterns of light and dark spots; base of wing pads darkened, their lateral margins pale. Legs yellowish ( Fig. 11 ) covered with pale clothing hairs; femura, tibiae, and tarsi with fringed of silky swimming hairs dorsally; femur covered with stout, brown setae, more abundant on posterior margin; stout, brown setae present on inner and outer tibia margins.

Abdominal terga ( Fig. 8) with wide, medial band of pale spots, bordered laterally by dark stripes and a row of pale spots at the margins. A faint, brownish median stripe may also be present. Posterior tergal margin with fringe of setae, intercalary bristles present. Cerci brownish ( Figs. 12–14 ), covered with clothing hairs; with both dorsal and ventral fringes of long, silky hairs in middle and apical segments. Distal ring of apical segments with whorl of short setae, each with one dorsal and one ventral long seta.

Material examined: Russia. Primorsky Region, Komissarovka R., lower Reshetinka R., 27. V 1998,. Tiunova, 5 nymphs; Khor R., IV 1961, I. Levanidova, 23 nymphs; Khabarovsky Region, Nemptu R., Muchen R. Basin, 30.VI 1959, I. Levanidova, 9 nymphs.

Distribution. Russia: Altai Mnts., Sayan Mnts., Transbaikal Region, Amur Region, Khabarovsky and Primorsky Regions, Sakhalin Island; Mongolia.

Figures

FIGURES 9 – 14. Isoperla asiatica: 9. Right maxilla, ventral. 10. Right mandible, ventral. 11. Right leg, dorsal. 12 – 14. Basal, medial, and apical sections of right cerci, lateral. Scale (mm): 11 = 0.51; 9, 10, 12 – 14 = 0.4.