Claassenia xucheni, Chen, 2019

Chen, Zhi-Teng, 2019, Description of a large new stonefly species Claassenia xucheni sp. nov. from China (Plecoptera: Perlidae), Acta Entomologica Musei Nationalis Pragae (Acta. Ent. Mus. Natl. Pragae) 59 (2), pp. 537-542 : 537-539

Claassenia xucheni sp. nov.

Type material. HOLOTYPE: ♁ (ICJUST): CHINA: CHONGQING CITY: Jiuchongshan National Forest Park, 31.89 N, 108.52 E, H: 1760 m, 18.vi.2019, light trap, Chen Xu leg. PARATYPES: 7 ♁♁ 2 ♀♀ (ICJUST), same locality and data as holotype.

Description. Male ( Figs 1–9 ). Body length (excluding antennae and cerci) 30.0–38.0 mm (n = 8), generally brown, with dark brown patterns.

Head ( Figs 1–3 ) wider than long, generally pale brown. Triocellate, each ocellus with dark inner margin; ocellar area with dark trapezoidal stigma. Compound eyes dark and round. Antenna dark brown and slender, slightly longer than abdomen. Maxillary and labial palps with apical segments shortest.

Pronotum ( Figs 1–3 ) nearly as wide as head, sub- -rectangular with obtuse corners. Pronotal disc mostly pale brown, margins dark, median suture dark but interrupted anteriorly; surface of pronotum scattered with irregular brown patterns. Meso- and metanota as wide as pronotum, mostly dark brown. Macropterous, wings pale brown, veins brown. Legs generally pale brown; apex of femur, base of tibia and tarsal segments dark.

Abdomen ( Figs 4–9 ) mostly pale; terga 2–8 with brown anterior margin and lateral surfaces. Tergum 9 laterally dark brown, each side with dark spot; median area of tergum 9 membranous with round patch of sensilla basiconica; spinal patch posterolaterally with two elliptical brown spots. Tergum 10 cleft into two parts, anterior margin of each part dark, sclerotized and apically touching triangular median sclerite; hemitergal lobes thick and finger-shaped, curved basally and sclerotized apically; posterior surface of hemitergal lobes with scattered, tiny sensilla basiconica; from lateral view, hemitergal lobes strongly upcurved, with uniform width except for tapered apices, ventroapical margins weakly sclerotized. Sterna 1–8 unmodified; sternum 9 with elliptical, rugose, hairy median sclerite, the sclerite with two anterior arms reaching lateral parts of tergum 9; posterior of hair patch with pale, elliptical hammer; posterior half of sternum 9 transformed into broad subgenital plate with C-shaped sclerite along caudal edge which medially touches hammer. Each end of C-shaped sclerite with small dark spot. Paraprocts long triangular and mostly brown, slightly upcurved but invisible from dorsal view. Everted aedeagus strongly curved forwards, completely membranous, without any conspicuous lobes or spines; apical half of aedeagus tongue-shaped, dorsally with several grooves. Cerci brown, very thick, subequal in length to abdomen.

Female ( Figs 10–14 ). Body length (excluding antennae and cerci) 40.0–41.0 mm (n = 2), general body color and pattern similar to males. Terga 9–10 brown, tergum 10 with triangular posterior projection. Sterna 2–5 each with pair of pale median spots. Posteromedial area of sternum 8 slightly sclerotized in one female paratype but unsclerotized in the other paratype; subgenital plate broad and slightly protruded posteromedially. Sternum 9 humped medially, with two brown lateral spots; median area of sternum 9 slightly sclerotized in one female paratype but unsclerotized in the other paratype; posterior margin of sternum 9 folded into two layers, posterior layer sclerotized and rugose. Sternum 10 mostly pale, posterolateral margins brown. Paraprocts long, triangular and mostly brown, slightly upcurved.

Extracted egg ( Fig. 14 ) acorn-shaped; chorion surface smooth and darkly sclerotized, without visible micropyles; collar and anchor degraded.

Etymology. The species is named after Mr. Chen Xu who collected and generously provided the specimens for study.

Biology. The holotype was caught by a light trap ( Figs 15–17 ), showing a positive phototaxis. The light trap was set near the unnamed river in the Jiuchongshan National Forest Park. The river was slow-flowing and green, and its substrate was limestone. Perennial plants constituted the dense forest on the mountains near the river, which provided perfect habitat for the emerged adults ( Fig. 15 ).

Distribution. China: Chongqing city ( Fig. 18 ).

Figures

Figs 1–9. Claassenia xucheni sp. nov., adult male. 1 – habitus, dorsal view; 2 – head and pronotum, dorsal view; 3 – head and thorax, ventral view; 4 – abdomen, dorsal view; 5 – terminalia and aedeagus, dorsal view; 6 – terminalia and aedeagus, lateral view; 7 – terminalia, ventral view; 8 – terminalia and aedeagus, ventral view; 9 – abdomen, ventral view.

Figs 10–14. Claassenia xucheni sp. nov., adult female. 10 – habitus, dorsal view; 11 – terminalia dorsal view; 12 – terminalia of one female paratype with median sclerites on sterna 8–9, ventral view; 13 – terminalia of the other female paratype without median sclerites on sterna 8–9, ventral view; 14 – egg taken from the female abdomen, lateral view.

Figs 15–17. Claassenia xucheni sp. nov. 15 – the type locality in the Jiuchongshan National Forest Park, China; 16 – light trap near the type locality; 17 – adult habitus on the light trap.

Fig. 18. Distribution of Claassenia species in China. Perlodes debilior Navás, 1934, a junior synonym of C. semibrachyptera described from the south part of Gansu Province is also indicated with a grey spot; another two synonyms, Perlodes brevipennis Navás, 1934 and Perlodes simplicior Navás, 1934, were described from the same locality as the types of C. semibrachyptera.