Rhopalopsole azun Stark & Sivec, 2012

Stark, Bill P., Sivec, Ignac & Shimizu, Takao, 2012, Notes On Rhopalopsole Klapálek (Plecoptera: Leuctridae), With Descriptions Of Three New Species From Vietnam, Illiesia 8 (13), pp. 134-140 : 135-136

Rhopalopsole azun Stark & Sivec sp. n.

( Figs. 1-4 )

Material examined. Holotype ♂, Vietnam, Gia Lai, An Khe District, Tram Lap, Azun River , 2 km NW on trail from forestry building, 14 ° 27’ N, 108 ° 33’ E, 23 June 1996, ROM 961084 , D.C. Currie, J. Swann ( ROM) . Paratype: Vietnam, Gia Lai, An Khe District , Tram Lap , small stream 0.5 km NW on trail from forestry building to Azun River, 900 m, 14 ° 27’ N, 108 ° 33’ E, 22 June 1996, ROM 961081 , D.C. Currie, J. Swann, 1♀ ( ROM) .

Male. General color in alcohol brown. Head and legs brown, without distinctive pattern. Wings uniformly brown with slightly darker veins. Forewing length 5.5 mm. Vesicle typical of the genus, rounded apically and attached to anterior margin of sternum 9 by narrow pedicel ( Fig. 2 ). Posterior margin of tergum 9 thickened slightly for a short section at midlength ( Fig. 1 ). Tergum 10 with a cordate shaped mesal sclerite offset from other sclerites by narrow membranous strips. Posterolateral margins of tergum 10 bearing prominent thorn-like processes; each process wide basally and scalloped on the posterior margin to form a long, narrow, sclerotized spine ( Figs. 1-3 ). Epiproct thick with rounded apex ( Figs. 1, 3 ). Cerci moderately long, subcylindrical, curved upward slightly in lateral aspect and bearing a small spine on the inner dorsoapical margin ( Figs. 1-3 ). Paraprocts fused into a caudally projecting process decurved at the tip and bearing numerous fine surface wrinkles; apex notched ( Figs. 1-3 ).

Putative female. General habitus similar to male. Forewing length 6.0 mm. Posteromedian margin of sternum 7 projecting slightly over base of sternum 8; sternum 7 sclerotized over much of surface, but with a small, posteromedian, square unpigmented zone ( Fig. 4 ). Sternum 8 with median transverse sclerite deeply incised on posteromedian margin. Sternum 9 sclerotized over most of surface, but with a small anteromedian unsclerotized lobe.

Larva. Unknown.

Etymology. The species name, used as a noun in apposition, is based on the Azun River type locality.

Diagnosis. The males of three species reported from Vietnam ( R. alobata Harrison & Stark 2008 ; R. sipang Sivec & Harper 2008 in Sivec et al. 2008; R. tamdao Sivec & Harper 2008 in Sivec et al. 2008) also have unforked, spine-like posterolateral processes on tergum 10. The former species, R. alobata , lacks a vesicle on male sternum 9, and R. sipang has much shorter posterolateral processes and a mesal spinule patch on tergum 9. The new species, an apparent member of the “magnicerca group” of Sivec et al. (2008), is similar to R. tamdao , and the two are distinguished by subtle characters of epiproct shape. The epiproct of R. tamdao is distinctly narrowed to an acute apex in dorsal aspect, whereas in R. azun this structure is scarcely narrowed in dorsal aspect and also appears thicker in lateral aspect ( Figs. 1, 3 ). An additional distinction occurs on the posterior margin of tergum 9. Rhopalopsole tamdao has a thickened band of minute knobs extending across much of the dorsal margin of tergum 9, narrowly connected mesally and not projecting caudally (see Fig. 5.1 in Sivec et al. 2008). In R. azun the thickened band is restricted to a narrow mesal zone ( Fig. 1 ). Rhopalopsole minima , described below, also shares many features with R. tamdao and R. azun but it differs from both species in having a pair of widely separated, thickened bands on the posterior margin of tergum 9 ( Fig. 5 ).

The female is associated on the basis of proximity of collection sites and may represent a separate species. The plate on sternum 7 is similar to that of R. tamdao , but the small transparent area on the posteromedian margin in that species is triangular in shape, and the sclerite on sternum 8 is divided (see Fig. 5.5 in Sivec et al. 2008).

Figures

Figs. 1-4. Rhopalopsole azun structures. 1. Male terminalia, dorsal. 2. Male terminalia, ventral. 3. Male terminalia, lateral. 4. Female terminalia, ventral.

Figs. 5-7. Rhopalopsole minima structures. 5. Male terminalia, dorsal. 6. Male terminalia, ventral. 7. Male terminalia, lateral.