Isoperla pseudornata Zhiltzova 1988

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 : 27-30

Isoperla pseudornata Zhiltzova 1988

( Figs.68–74)

Description. Association with adults was established by rearing nymphs from the Barabashevka and Zanadvorovka Rivers. Length of mature male nymph 8.7–9.3 mm, female 10.2–11.1 mm; length of male cerci 3.5–4.0 mm, female 5.0– 5.5 mm. General body color yellowish­brown, head and thorax pale ventrally, abdominal sternites pale brown to the tip. Clothing hairs dark and numerous.

Head with occiput setal row interrupted medially ( Fig. 68); brown, M­shaped pigment band across middle, interocellar area with pale triangular spot, open posteriorly, this triangle connected to pale tentorial pits by transverse pale stripes; occiput pale brown with indistinct, small triangular spot medially and two lateral oval spots; anterior of frontoclypeus with dark, transverse band and with two small pale spots; labrum yellow. Lacinia bidentate ( Fig. 69 ), subapical tooth slightly hooked, inner margin with 5–6 stout setae and short, thin pale setae below subapical tooth. Galea short, barely reaching subapical tooth base. Mandible ( Fig. 70 ) similar to other species considered here.

Pronotum ( Fig. 68) evenly fringed with pale, short setae, occasional longer setae interspersed at posteriolateral corner; pale mesal patch with indistinct margins; lateral fields and anterior and posterior margins dark; lateral pronotal margins light. Meso­ and metanotum ( Fig. 68) with pale, triangular, mesal spot that is widened anteriorly, meeting darker lateral field in a complicated pattern; bases of wing pads forming darkish sublateral, longitudinal bands; lateral margins and tips light. Legs ( Fig. 71 ) yellowish, with a dense fringe of silky swimming hairs along outer margins of femora, tibiae, and tarsi.

Abdominal terga ( Fig. 68) with mesal longitudinal row of light rounded spots, median line of abdomen slightly darken, row of light spots contrasting with sublateral, brown, longitudinal stripes, which widen the anterior margin of each tergum; lateral tergal margins pale; posterior terga margins with fringe of long brown setae; numerous dark intercalary bristles present. Cerci ( Fig. 72–74 ) brownish, covered with thin clothing hairs; apical half with sparse dorsal fringe of silky hairs, length of hairs do not exceed the length of the corresponding cercal segment; apical whorl in apical third of cerci with one dorsal and one ventral setae longer than others, their maximum length exceeds half the corresponding segment length.

Material examined: Russia. Primorsky Region, Zanadvorovka R., 26.V 1998, V. Teslenko, (reared), 1 nymph; Barabashevka R., 19.VI 2003, V. Teslenko, (reared), 47 nymphs; Bolshaya Ussurka R., 8.VI 2004, V. Teslenko, 1 nymph.

Distribution. Russia: Primorsky Region.

Figures

FIGURES 69 – 74. Isoperla pseudornata: 69. Right maxilla, ventral. 70. Right mandible, ventral. 71. Right leg, dorsal. 72 – 74. Basal, middle, and apical sections of right cercus, lateral. Scale (mm): 71 = 0.51; 69, 70, 72 – 74 = 0.4.