Sphaeronemoura asymmetria, Li, Weihai, Yang, Juan & Yang, Ding, 2016

Li, Weihai, Yang, Juan & Yang, Ding, 2016, Two new species of Sphaeronemoura (Plecoptera: Nemouridae) from Oriental China, Zootaxa 4208 (3), pp. 293-300 : 294

Sphaeronemoura asymmetria sp. n.

( Figs. 1 & 3 )

Diagnosis. Male tergum VIII has a large, bilobed plate overhanging tergum IX, right side much larger. Male paraproct bears inner lobes longer than the nipple-like median lobes. Flagellum of male epiproct is double curved in lateral view, with acute apex. Male cercus is nearly parallel-sided in lateral view, tip stout and indented.

Description. Body length ca. 7.6 mm, forewing length ca. 9.4 mm, hindwing length ca. 8.2 mm. General color dark brown without pattern; antennae brown, apex missing. Pronotum brown with scattered rugosities. Legs dark brown with tarsi brown; wing membrane brownish, venation darker. Abdomen brown but with terminal segments dark brown. Pilosity generally short, with some long hairs on terminal segments.

Male terminalia ( Figs. 1 a–g, 3a–f): Hypoproct mostly brown with apex dark brown and wrinkled, about one third of the width of sternum IX, basally subquadrate, median portion abruptly tapering to tubular and upcurved tip; vesicle claviform, ca. 3X longer than wide, basal part slightly constrict, lateral margins distinctly sclerotized ( Figs. 1 b–c & 3b–c). Paraproct ( Figs. 1 b, 1g, 3b & 3f): inner lobe brown, basally triangular with acute spine-like apex, nearly as long as wide, much longer than median lobe. Median lobe with nipple-like projection, tip rounded, brown in color. Outer lobe heavily sclerotized, basally forming a strip curved around the cercal base, then extended to the apex of median lobe, apex spoon-shaped. Cerci ( Figs. 1 a–d & 3a–c) stout but basal portion narrow in dorsal view, generally parallel-sided in lateral view, slightly curved inward, apex medially indented, with a median scar-like segment reminant, and an apical nipple in lower aspect ( Figs. 1 b–1d). Tergum VII brownish, posterior margin produced medially, produced area tougue-shaped in lateral view ( Figs. 1 a, 1c, 3a & 3c). Tergum VIII brown, with very large, darker median plates nearly overhanging entire tergum IX; protruding lobes as wide as long but the right side much larger ( Figs. 1 a & 1c). Tergum IX mostly sclerotized, antecosta thickened, with a deep triangular posteromedial indentation under protruding lobes of tergum VIII. Tergum X well sclerotized with thickened antecosta, medial fifth part of the segment under epiproct completely membranous. Tergal projections located beneath the apex of epiproct, acute and erect in lateral view but slender transversal strip in dorsal view. Epiproct typical for the genus, nearly trapezoidal with apex constricted in dorsal view, apex indented medially ( Figs. 1 e–1f, 3c–e). Dorsal sclerite with well sclerotized trapezoid base divergent into thin lateral branches, sclerite terminating at midlength of epiproct, appearing triangular in lateral view, apex slightly curved downwards in lateral view. Ventral sclerite basal portion nearly paralell with dorsal sclerite before fusion with dorsal sclerite at midlength, apically slightly bilobed with paired darkly sclerotized, fish-like sclerites before base of flagellum, bearing several sharp teeth along the enlarged ventral ridge. Flagellum singlely curved in dorsal view but double curved in lateral view, and lightly pigmented beyond the second curve, medially grooved at basal half where is clearly seen in dorsolateral view.

Female: unknown.

Larva: unknown.

Type material: Holotype ( HIST) ♂: CHINA: Guizhou, Daozhen County, Dashahe, tributary of Furong River , N 28°07.49', E 107°58.92', 2006. VIII.24, leg. Chunfeng Jia.

Distribution. Southwest China (Guizhou).

Etymology. The specific name refers to the asymmetrical protruding lobes of tergum VIII.

Remarks. The new species is closely related to S. separata Li, Muranyi and Yang, 2014 from Henan, central China, but S. asymmetria is distinguished from the latter by the triangular inner lobe of paraproct bearing an acute apical tip. In Sphaeronemoura separata , the inner lobe of paraproct is finger-like with blunt apex.

The holotype may be a teratological specimen due to the asymmetrical protruding lobes of tergum VIII. Similar asymmetrical tergal structures have been reported in the nemourid genus Mesonemoura , such as M. tibetensis Zhu, Yang & Yang, 2003 , M. multispira ( Wu 1973) and recently described M. dilatata Du & Ji, 2014 and M. sinistracurva Du & Wang, 2014 . However, asymmetrical structures are not known for any species of Sphaeronemoura . Unfortunately, no additional specimens are available to confirm the uniqueness of the type.

Figures

FIGURE 1. Sphaeronemoura asymmetria sp. n. Male. a: terminalia, dorsal view; b: terminalia, ventral view; c: terminalia, lateral view; d: terminalia, laterodorsal view; e: epiproct, dorsal view; f: epiproct, lateral view; g: paraproct, caudal view.

FIGURE 3. Sphaeronemoura asymmetria sp. n. Male. a: terminalia, dorsal view; b: terminalia, ventral view; c: terminalia, lateral view; d: terminalia, anterodorsal view; e: epiproct, dorsal view; f: paraproct, caudolateral view.