Arcynopteryx amurensis Zhiltzova et Levanidova, 1978

Teslenko, Valentina A., 2012, A taxonomic revision of the genus Arcynopteryx Klapálek, 1904 (Plecoptera, Perlodidae), Zootaxa 3329, pp. 1-18 : 5-8

Arcynopteryx amurensis Zhiltzova et Levanidova, 1978 .

( Figs 13–21 )

Zhiltzova & Levanidova 1978: 11−13, figs 13−15; Zhiltzova & Zapekina-Dulkeit, 1986: 182, figs 4, 9; Teslenko & Zhiltzova, 2009: 26, figs 129−131.

Diagnosis. The submental gills are very small or almost completely reduced in both sexes. A. amurensis can be distinguished by the shape of the hemitergal lobe, which is elongated, fingerlike, directed forward and upward, and narrowed to the tip ( Figs 14−17 ). A knob is absent. The cowl of the epiproct is shallow; the lever arm is stout, short and slightly curved ( Fig. 17 ). The lateral sclerotized bands resemble a small folded leaf, with the pointed tip directed upward and downward; the stylet of the epiproct is short, without a loop, and the base is oval, wide and well sclerotized ( Fig. 17 ). The top of the stylet of the epiproct in A. amurensis is directed upward and backward, similar to A. polaris and A. sajanensis . The aedeagus is large, membranous, sac-shaped, with two small fingerlike rounded lobes dorsolaterally; one transverse swelling presents ventrally; the apex is weakly widened, with two large rounded swellings, and bears fine, erect, clear spinules dorsolateraly ( Figs 14 & 15 ). The female can be separated from females of other species by the shape of the lobes on the posterior margin of the subgenital plate, which are short, widely placed, and slightly transverse; the rear edge of each lobe is straight; the lobes are slightly sloping, and the medial angle of each lobe is slightly elongated ( Fig. 18 ). The egg is large; collar with several sharp longitudinal carinae, continued to the shoulder; the margin of the shoulder is rough ( Fig. 20 ); the chorion is covered with hexagonal FCIs ( Figs. 19, 21 ); the FCI walls are tuberous, raised with thick furrows; the floors contain 7–13 tubercles ( Fig. 21 ).

Adult habitus. The general body pattern is brown, with dark spots on the head and thorax. The pigment patterns of the male and the female differ in certain respects, especially in the color of the head and pronotum. On the head of the female ( Fig. 13 ), the M-line, frontal callosities, interocellar area and medial part of the occiput are pale, with very diffuse outlines. On the head of the male, the general pattern is also pale and then grades into brownish; a dark spot is clearly distinguishable between the M-line and the median ocellus; dark patches are located around the compound eyes and occiput laterally; darkish patches are present in front of the median ocellus and along the anterolateral edges of the clypeus. The palpi and submentum are light brown, and the submental gills are not developed; only short triangular projections are visible in their places. On the pronotum of the male, a pale medial band is well pronounced, expanding anteriorly and posteriorly; on the pronotum of the female, the medial band is brownish, somewhat lighter than the lateral fields ( Fig. 13 ). The pronotum is slightly transverse, with rounded corners. The mesanotum of the male bears a pale stripe, expanding to the anterior and posterior margins. The female has a pale stripe on the prescutum of the mesonotum only. The wings are shortened, the venation somewhat changed: the apical branches of the veins are very short, with a network of crossveins in the RS and sometimes in the M, Su1 and Cu2. The female has brown legs, the male brown-yellow legs. The abdomen of both the male and the female is brown dorsally and pale ventrally. The cerci are longer than the abdomen, brown, covered with small brown setae and long strong brown hairs. Each cercal segment bears a narrow pale ring basally.

Male. Body length 16.0−19.0 mm, the length of shortened forewing 3.5–6.0 mm. The abdominal sterna are pale with brown lateral margins; sternum 9 is completely brown, scoop-shaped, extended backward and curved upward. Tergum 9 is lighter than the other abdominal terga, with a pale membranous stripe along the median line, expanding anteriorly; the posterior margin with submedial, transversely elongated and rounded swellings, densely covered by small stout setae and fine colorless hairs posterolaterally ( Fig. 14 ). Tergum 10 is divided into two hemiterga ( Fig. 14 ); the posteromedial edge of each hemitergal lobe is elongated, finger-like, curved and directed forward and upward, narrowed to the tip, dark with a light, slightly curved tip, covered by small, stout setae dorsally ( Figs 14−17 ); a knob is absent. The cowl is membranous, folded, resembles a shallow pouch between and under the hemitergal lobes, is attached around the sclerites of the internal basal anchor ( Fig. 17 ). The cowl opens dorsally in a slit. The dorsolateral edges of the cowl are large, supported by darkly sclerotized paragenital plates. In a lateral view, the arrow-like sclerites of the internal basal anchor are black, fragile, and hidden under tergum 9 ( Figs 14 & 17 ). The lever arm is stout, hollowed, and relatively short and slightly curved ( Fig. 17 ). Two sclerotized lateral bands and the stylet of the epiproct are fastened ventrally to the lever arm directly. The lateral sclerotized bands resemble a small folded leaf with the tip directed upward and downward; the base of each lateral band is wider than the top ( Fig. 17 ). The stylet of the epiproct is short, without a loop, visible as a strong bristle directed upward and backward or obliquely backward and downward; the base of the stylet is oval, wide and well sclerotized ( Fig. 17 ). The everted membranous aedeagus is large, sac-shaped, with two small finger-like rounded lobes dorsolaterally, directed forward, covered by small spines; one transverse swelling presents ventrally; the apex is weakly widened, with two large rounded swellings, and bears fine, erect, clear spinules dorsolateraly ( Figs 14 & 15 ).

Female. Body length 18.4−21.0 mm; wings are shortened, the length of forewing 6.8−18.5 mm. The subgenital plate is indistinctly detached from the lateral parts of sternum 8; the posterior margin of the subgenital plate bears two short, widely placed, slightly transverse lobes, the rear edge of each lobe is straight ( Fig. 18 ); the lobes are slightly sloping, and the medial angle of each lobe is slightly elongated. Sternum 9 bears two dark spots mesolaterally ( Fig. 18 ). Tergum 10 is triangular posteriorly and deeply depressed medially.

Egg is ovular ( Fig. 19 ), circular in cross-section and large 572-643 X 365-396µm. Anchor mushroom-shaped with short and strong pedicel ( Figs 19 & 20 ) and two or three rows of globular bodies close to the margin of the anchor plate. The margin of the anchor covers the collar completely ( Fig. 19 ). The collar is stalked, its rim flanged and irregularly incised. The sides of the collar bear sharp longitudinal carinae continued to the shoulder; the margin of the shoulder is rough ( Fig. 20 ). The chorion is covered with hexagonal FCIs ( Figs 19, 21 ); the FCI walls are tuberous, raised with thick furrows; the floors contain 7–13 tubercles ( Fig. 21 ). Row of micropyles is subequatorial; orifices small with indistinct lips are surrounded by pentagon rosettes ( Fig. 21 ).

Material examined. Holotype, male. Russia. Khabarovskyi Region, Silinka River, Amur River Basin, 19.07.1974. Paralectotypes: 1 female, the same place; coll. T. Kuznetzova. Magadan Region, 1 male, Olen’ stream, Sibit-Tyellach settlement, Aborigen station, 4.07.1977; 2 females, Ozernyi stream, the same place, 4. 0 7.1977.

Distribution. Russia, Far East (South of the Magadan Region, Khabarovskyi Region).

Figures

FIGURES 13 – 18. Arcynopteryx amurensis: 13. Head and pronotum of female. 14. Male abdominal tip with aedeagus, dorsal. 15. Same lateral. 16. Male left hemitergal lobe, dorsal. 17. Cowl: sclerites of the internal basal anchor, lever arm, paragenital plate, hemitergal lobe, stylet of the epiproct, and two lateral sclerotized bands, lateral. 18. Female abdominal tip, ventral. Scale (mm): 16, 17 = 1.0. Figures 14, 15, 18 after Zhiltzova & Levanidova 1978.

FIGURES 19 – 21. Arcynopteryx amurensis, egg: 19. Habitus: anchor, chorion structure, row of micropyles, lateral. 20. Collar and pedicel, lateral. 21. Chorion structure and micropylar orifice, mounds, and pentagon rosettes, dorsal view.