A New Stonefly Species, Rhopalopsole tricuspis (Leuctridae: Plecoptera), and Three New Records of Stoneflies from the Qinling Mountains of Shaanxi, China

Plecopteran species (Leuctridae) were collected from the Qinling Mountains in southern Shaanxi Province, China. This mountain range is home to nine species of Leuctridae belonging to two genera, and the species identified in this work include one new species and three new records for the Qinling Mountains, all belonging to the genus Rhopalopsole. The new species is named R. tricuspis Qian and Du, sp. nov. A redescription of R. basinigra Yang and Yang 1995 is supplemented. A key is provided for the adult males of Leuctridae from the Qinling Mountains.

Specimens in this study were collected from the Qinling Mountains, located in southern Shaanxi Province, China. The Qinling Mountains are an ancient fold-fault; the land began rising as early as 400 million years ago and formed the present landscape pattern about 80 million years ago (Wang 2005). It has an average elevation of 2000 to 3000 meters, with its highest mountain, Mt. Taibai, reaching an elevation of 3767 meters (Ying 1994). The Qinling Mountains include five national nature reserves and the Crested Ibis Protection Observation Station, with a total area of 2180 km 2 (Zhang and Li 1997).
The mountains not only form the watershed between the Yangzi River and the Yellow River and create a natural boundary between the north and south of China-they also act as a boundary between the temperate and subtropical zones (Zhang et al. 1979). The Qinling Mountains are also an abundant biodiversity region, and were deemed to be a boundary between the Oriental and Palearctic Regions in China (Zhang et al. 1999). Thus, it is a key area to study Chinese insect fauna. In the present paper, one new species of Rhopalopsole is described, and revisions are made to some known species of leuctrids in the area. The materials studied are deposited in the Insect Collection of Yangzhou University, Jiangsu, and all specimens are preserved in 75% ethanol.  Yang and Yang, 1995 Adult habitus. Head dark brown, wider than prothorax, three ocelli, hind ocelli much closer to the eyes than to each other, antennae yellowish brown, palpi light brown. Prothorax light brown, quadrate, longer than wide, angles rounded and some brown stripes on it. Legs light brown. Wings hyaline, veins light brown.

Rhopalopsole basinigra
Male. Body length 6.0 mm, length of forewing 5 mm. Ventral lamella on tergum 9 rounded (Figure 2), a small fairly sclerotized semicircular ridge jutting out before the midposterior margin, with mid-posterior margin indented (Figure 1). Tergum 10 with a central sclerotized plate, two sclerotized stripes stretching downward to the posterior margin in the middle of the central plate; the posterior margin of plate more sclerotized, transverse sclerites triangular-semicircular with rounded angles (Figure 1). Posterolateral processes very long and narrow, reaching just beyond the mid-line of segment 10, thus crossing over the tip of the corresponding process from the other side (Figures 1 and 3). Epiproct stocky and upper curved, apex flattened, in dorsal view with a trilobed tip with rounded angles (Figures 1 and 4), a spine in the middle lobe located at a short distance to the tip ( Figure 5).
Remarks. Yang (1995) did not describe in detail R. basinigra. We checked the types of R. basinigra in the Insect Collection of Beijing Agricultural University. It has a ridge that juts out before the mid-posterior margin of tergum 9; with long lateral processes reaching beyond the mid-line of tergum 10; apex of epiproct flattened, with a trilobed tip and a downcast spine in the middle lobe at a short distance to the tip. Epiproct of some species like in Figure 4 having one parallelsided, though Figure 1 does not-they may have variations.
Male. Body length 5.0 mm, forewing length 5.5 mm. On tergum 9, the ventral lamella somewhat large and rounded (Figure 7), a sclerotized speckle before the mid-posterior margin, slightly indents at mid-posterior in dorsal view (Figure 6), two small spines jut out in ventral view (Figure 8). Tergum 10 with a small central plate and two lateral bulging lobes on each side of central plate, transverse sclerites triangular with rounded angles (Figure 6). Posterolateral processes extending upwards and triangular-like in lateral view (Figure 8). Epiproct thick, elongate and upper curved, terminating in a flattened, trilobed tip with rounded angles in dorsal view (Figures 6 and 9), an L-like projection and upper curved in lateral view (Figure 8). Subanal lobe upturned in lateral aspect (Figure 8) separated into a basal ventral lobe and two upper distal lobes, upper distal lobes more sclerotized and tip sharp ( Figures  6 and 7). Cerci short and distinctly upturned in lateral aspect, no spine (Figure 8).

Female. Unknown.
Etymology. The species name is derived from the shape of the epiproct in dorsal view.
Remarks. This new species seems similar to R. shaanxiensis group (Sivec et al. 2008). It seems similar to R. qinlinga Sivec and Harper 2008 in having two lateral bulging lobes on each side of central plate, epiproct thick and flattened in dorsal view. But it can be distinguished from R. qinlinga by the outline of tergum 9, epiproct distal ends and subanal lobe. In R. qinlinga, no ridge juts out before the mid-posterior margin of tergum 9, epiproct distal ends blunt rounded and no split, subanal lobes separated into a basal lobe and an upper distal lobes in ventral view, each with strong dark sclerotized stripes on it.