Sinacroneuria acuticornis Uchida, 2017

Li, Weihai, Murányi, Dávid, Orci, Kirill Márk, Uchida, Shigekazu & Wang, Rongfeng, 2017, A new species of Sinacroneuria (Plecoptera: Perlidae) from Guangxi Zhuang Autonomous Region, southcentral China based on male adult, larva and drumming signals, and validation of the Japanese species of the genus, Zootaxa 4299 (1), pp. 95-108 : 102-106

Sinacroneuria acuticornis Uchida , sp. n.

( Figs. 38–44 )

Nishineuria cornuta Uchida, 1990 — Uchida 1990: 126. (manuscript name; original description of the male and larva). Acroneuriini incerta sedis — Shimizu et al. 2005: 265. (key, and illustrations on the male and larva).

Type materials. Holotype male ( LBM), Japan: Honshu, Ishikawa Prefecture, Yoshinodani-mura, Chȗgȗ, Hakusan Nature Conservation Center, 1980. VIII.31–IX.2, leg. P. Zwick . Paratypes: same locality and date: 1 male and 2 females ( CPZ) ; Nara Prefecture, Tenkawa-mura, Ten-kawa River , 610 m, 1982. X.9: 1 female ( LBM) .

Adult. General body color yellow with brown marks. Triocellate, with a central brown mark among ocelli. Antennae brown. Median area of thorax brown. Wings weakly smoked except anterior margins. Tibia brown but proximal and distal ends yellow. Abdomen and cerci yellow.

Male. Terga 1–6 and sterna 2–8 without modification. Terga 7–10 depressed posteromedial; depressions increasingly enlarged on posterior segments ( Figs. 38–39 ). Tergum 9 with short bristles and sensilla basiconica on depression; they are dense laterally, sparse medially. Sternum 9 hammer, small, oval, well sclerotized ( Figs. 40– 41 ). Membranes in sides of hammer hairy, convex anteriorly, concave posteriorly. Tergum 10 with a pair of bristle patches on sides of depression; bristles also short; center of depression, where vestige of epiproct is incorporated, further depressed. Paraproct with a short pointed hook. Aedeagus ( Figs. 42–44 ): consisting of three telescoped regions typical of Perlidae , but tube short and inconspicuous. Envelope with fine golden spinules which are simple (proximally) or comb-shaped (distally) on dorsal side ( Fig. 43 ); spinules on ventral side arranged on scales, each of which bears several spinules. Fold between envelope and tube with a pair of accessory glands dorsolaterally. Tube dorsally with a pair of large horn-shaped sclerites, slightly curved laterad (Y-arms); stem a broad, flat sclerite. Basal margin of tube with sparse hairs laterally ( Fig. 44 ). Sac dorsally with a sclerotized bar, ventroapically with a patch of fine golden spinules.

Female. Sternum 8 slightly but widely produced caudad; posterior margin slightly concave medially; dorsal side posteriorly sclerotized.

Larva. Generally similar to the above species, color pattern as in Shimizu et al. (2005: fig. 14.4).

Distribution and ecology. Sinacroneuria acuticornis is restricted to Honshu Island, Japan, being the only currently known Palaearctic species of the genus. It is known from Ishikawa, Shizouka ( Shimizu et al. 2005) and Nara prefectures. It can be considered as a potamal species, occurring in low densities and having a late summer emergence period.

Etymology. The name acuticornis (from the Latin words acutus, meaning acute, and corni, meaning horn) refers to the acute sclerites of the aedeagus. Used as a possessive pronoun, gender neutral.

Remarks. The male of this new species is unique in having medially reduced but not fully divided sensilla basiconica patch of tergum 9. A divided patch is known only for S. orientalis and S. obscura ; all other known males of Sinacroneuria have the patch fused and a laterally reduced sensilla basiconica patch on tergum 9. In addition, both the stem and Y-arms of aedeagal sclerite are exceptionally large and stout on the Japanese species. Females are known only for three other Sinacroneuria species and are difficult to distinguish; relying on color patterns, as also for the larva.

Figures

FIGURES 38 – 44. Sinacroneuria acuticornis Uchida, sp. n., holotype male. — 38: terminalia, dorsal view; 39: terminalia, dorsolateral view; 40: terminalia, ventral view; 41: sternum 9, lateral view; 42: aedeagus, dorsal view; 43: aedeagus, lateral view, with details of spines; 44: aedeagus, ventral view—scale 1 is 1 mm, for all figures but scale 2 is 0.05 mm for the details of Figs. 43 – 44.