Isoperla lunigera ( KLAPÁLEK, 1923b )

Zwick, P & Surenkhorloo, P, 2005, The Mongolian Species Of Isoperlinae (Plecoptera: Perlodidae), Acta Zoologica Academiae Scientiarum Hungaricae 51 (3), pp. 253-276 : 256-259

Isoperla lunigera ( KLAPÁLEK, 1923b)

( Figs 1 , 2 , 5a )

Chloroperla lunigera KLAPÁLEK, 1923 , Ann. Soc. Ent. Belg. 63: 26.

Isoperla lunigera – ZWICK et al. 1971, Ent. Obozr. 50: 862.

Isoperla flavescens ZHILTZOVA et POTIKHA – PUREVDORJ et al., 2003, misidentification.

Material studied. MONGOLIA, Selenge aimak, Mandal sum: Khonin Nuga , Eroo River [49°05’N, 107°17’E], 2 mm, 14. VI.2002; 3 mm, 8 ff, 17./ 18.VI.2002; 2 mm, 6 ff, 16.VI.2003; 2 mm, 4 ff, 19.VI.2003; 4 ff, 21.VI.2003; 5 ff, 26.VI.2003; 1 f, 4.VII.2003; 40 ff, 2 mm, 6.VII.2003; 2 ff, 1.VIII.2003; 3 mm, 1 f 4.VIII.2003; Khonin Nuga, Khongi River , 1 f, 19. VI.2003; Eroo Hot Spring [49°05’N, 107°17’E], Ar-Ilchlekh River, tributary of Sharlan River , 1 f, 28. VI.2003; upper reaches of Bar-Chuluut River [48°58’638N, 106°57’013E], tributary of Eroo River , 2 larvae, 21. VIII.2001 (in coll ZWICK) (all leg. P. SURENKHORLOO). We also studied additional specimens from the Russian Far East, in our collections .

I. lunigera has a characteristic contrastive head pattern ( Fig. 1a ). The species was redescribed by ZWICK et al. (1971), after comparing some fresh material from of anchor in broken lines the Amur region and Primorje in the Russian Far East with the female holotype (from Irkutsk, in Mus. St. Petersburg) .

Size. Front wing length, mm 10.3–11.0 mm, ff 11.2–11.7 mm.

Male. We reprint the figure of the distinctive, large, symmetrical penial sclerite ( Fig. 2 ) for comparison with I. altaica and I. eximia .

Female. The strongly pigmented brace-like subgenital plate ( Fig. 1b ) is characteristic. There are earlier descriptions and figures, respectively ( ZWICK et al. 1971, ZHILTZOVA & ZAPEKINA-DULKEIT 1986). Dissections revealed a wide funnel-shaped entry into the female copulatory pouch which houses a small dark heart-shaped sclerite. The oviducts attach anteriorly. Dorsally, the pouch carries a bag-like extension apparently receiving the large male sclerites during copulation. The long duct of the oval seminal receptacle is attached at the front of this extension and carries more than 10 accessory glands.

Egg ( Fig. 1e, f ). Smaller than the eggs of other Mongolian Isoperla species, only 250×170 µm, collar included. Chorion very thin, about 4 µm thick, seemingly structureless. However, at magnification 650, very fine shallow punctuation appears. Collar simple and short; its base is forming a rounded projection into the egg. On the outside, the collar has several horseshoe-shaped impressions separated by minute longitudinal crests. Anchor fungi-form with massive stalk. Micropyles not observed.

Larva ( Fig. 5a ). One of the larvae from Bar-Chuluut River contained some of the characteristic eggs; its pattern is quite similar to the larva ascribed to I. altaica by ZAPEKINA-DULKEIT (1955).

Diagnostic characters and affinities. Head pattern, penial sclerite and the brace-like pigmented female subgenital plate are distinctive. The female subgenital plate has some resemblance with Kaszabia spinulosa whose plate is, however, much longer ( RAUŠER 1968, ZHILTZOVA & ZAPEKINA-DULKEIT 1986). Glands on the seminal receptacle and its duct are a synapomorphy of Systellognatha ( ZWICK 2000) but the heart-shaped sclerite in the genital pouch of the present species is unusual.

Notes. The present species was recorded from Mongolia as Isoperla flavescens ZHILTZOVA et POTIKHA ( PUREVDORJ et al. 2003), in error; I. flavescens is not known from Mongolia. For affinities of I. lunigera , see under I. eximia .

Figures

Fig. 1. Isoperla lunigera (KLAPÁLEK). a = head and pronotum, b = female sternite 8, c = dissected sternites 8 and 9 in dorsal view, showing genital pouch, receptacle, andaccessory glands; d = detail of genital pouch and receptacle, e = egg, f = detail of collar indicating chorion thickness and inner parts

Fig. 2. Isoperla lunigera (KLAPÁLEK). a–c = penis sclerite in lateral, oblique lateral, and caudal views, respectively (from ZWICK et al. 1971)

Fig. 5. Larvae of Isoperla spp. a =I.lunigera (KLAPÁLEK), b–d = I.altaica ŠÁMAL, with details of labium and labial segment