Isocapnia guentheri ( Joost, 1970 )

Isocapnia guentheri ( Joost, 1970) View in CoL

( Figs. 4–6 View FIGURE 4 )

Capnia guentheri Joost, 1970: 38 View in CoL .

Isocapnia guentheri View in CoL : Zhiltzova 1972: 122; Zhiltzova 2003: 404; Zenger & Baumann 2004: 81; Teslenko & Bazova 2009: 1061; Teslenko & Zhiltzova 2009: 182; Judson & Nelson 2012: 20 View Cited Treatment ; Chen & Du 2017: 20.

Female ( Figs. 4–6 View FIGURE 4 ). Forewing length 6.9 mm (n=1). Body generally dark brown. Head slightly wider than pronotum; compound eyes black, three ocelli each with obscure dark margins ( Fig. 4a View FIGURE 4 ). Precoxal bridge fused with basisternum; furcasternum fused with basisternum and furcasternal arms ( Fig. 4b View FIGURE 4 ). Wings macropterous, subhyaline with brown venation; forewings with two costal cross veins before end of Sc ( Fig. 5). Sternum 8 medially membranous, subgenital plate deeply incised, and the sclerotized portion flush with the preceding membrane, lateral sclerites subtriangular with rounded angles ( Fig. 6c View FIGURE 6 ).

Material examined. 1 female ( HIST), China: Heilongjiang Province, the Greater Khingan Mountains area, Huzhong District, Xiangyang South Road , Dabaishan Hotel , 522 m, 51.6001º N, 124.3540º E, 2023. VIII. 10. leg. Weihai Li, Yao Zhang. GoogleMaps

Distribution. Eastern Palaearctic species. China (Heilongjiang Province); Mongolia; Russian Far East (from Chukchi Peninsula to Primorskii Territory and Sakhalin Island).

Remarks. This species was originally described from Mongolia ( Joost, 1970) and has also been documented throughout the Russian Far East ( Zenger & Baumann 2004). This is the first record of this species, and the fourth species of this genus recorded from China ( Yang & Du 2024). Sternum 8 simply and straightly truncate but exhibits a typical blunt V-shaped pattern ( Fig. 6a View FIGURE 6 ). There are some slight variations in the female subgenital plate. Sternum 8 with membranous pale area at medial portion anteriorly. Subgenital plate is reduced, forming only a semicircular median sclerite on the posterior margin of sternum 8, accompanied by a pair of lateral sclerites. Sternum 9 with two sclerotized spots on each lateral portion (comparing Figs. 6c–d View FIGURE 6 with Fig. 6b View FIGURE 6 ). The subgenital plate of this female are generally in close agreement with the illustrations in Teslenko (2009). And there is a minor difference with the original illustrations ( Joost 1970). However, the general shape in outline is identical and hence considered here as intraspecific variation.