Mesonemoura spiroflagellata ( Wu 1973 )

Du, Yu-Zhou, Wang, Zhi-Jie & Zhou, Pei, 2007, Two new species of the genus Mesonemoura and redescription of M. spiroglagellate (Plecoptera: Nemouridae) from China, Zootaxa 1495, pp. 47-52 : 50-52

Mesonemoura spiroflagellata ( Wu 1973)

( Fig. 16–23 )

Adult habitus. Head dark brown, near equal in width to pronotum; wings subhyaline to brown; legs brown. Cervical gills single, short and oval, each one located lateral to cervical sclerite.

16 17 18 19 20 21 23 22 Redescription of Male. Forewing length 7.3–7.8 mm, hindwing length 5.8–6.2 mm. Tergum 9 slightly sclerotized, posteromedian margin deeply concave, concavity nearly reaching anterior margin of concavity bearing a few stout spines. Tergum 10 slightly sclerotized but with a darkly sclerotized strip below flagelliform projection of epiproct, forming a large concave area anterior to base of epiproct. Hypoproct tapering with a narrow apex, covering parts of inner lobes of paraprocts; vesicle length 3– 4 X width, but narrow at base. Cercus long, length 2.5X width. Paraprocts divided into 3 lobes; inner lobe triangular, lightly sclerotized but darkly sclerotized along midline of the lobe; median lobe partially sclerotized, forming a long sclerotized bar, ended with a strongly sclerotized hook without spines, membranous area broad at base with many hairs; outer lobe long, the base thin and sclerotized, curved around cerci. Epiproct a narrow rectangle, mostly sclerotized; dorsal sclerite hyaline and colorless, apical portion slightly enlarged ventrally and extending over ventral sclerite; lateral arms darkly sclerotized and dark brown; ventral sclerite slightly sclerotized, broad at base and becoming narrower toward apex, the apex extended distally forming a long and slender flagelliform, sclerotized structure; ventral sclerite without spines; the flagelliform projection inserted into abdominal tergum from posteromedian of tergum 9, with a single spiral, the length is about 2.5X the length of the epiproct.

Female. Forewing length 8.3–8.9 mm, hindwing length 8.1–8.6 mm. Sternum 7 produced at distal margin, extending slightly on to sternum 8 at midline, produced area lightly sclerotized and elevated; sternum 8 with a large sclerotized, emarginate, triangular plate.

Examined specimens. 3 m and 2 f, Huanglong, Sichuan province, 3080 m, 22 Aug. 1994, Leg. Du Yu- Zhou; 14 m and 5 f, Huanglong-channel, Sichuan province, 3100 m, 22 Aug. 1994, Leg. Du Yu-Zhou.

Remarks. After checking the types of M. spiroflagellata ( Wu 1973) deposited in the Collection of Institute of Zoology Chinese Academy of Sciences, we found that there were some discrepancies between the types and the illustrations drawn by Wu (1973), so we redescribe this species. In addition, comparing our specimen to Wu’s types, we found that the cercus of our specimen are much longer than the latter, in spite of this, we still consider that they are the same species with some geographic variation.

Figures

FIGURES 16 – 23. Mesonemoura spiroflagellata (Wu 1973). 16. Male terminalia, dorsal; 17. Male terminalia, ventral; 18. Male terminalia, lateral; 19. Male paraproct (left); 20. Male epiproct, dorsal; 21. Male epiproct, ventral; 22. Male epiproct, lateral; 23. Female terminalia, ventral.