Mesonemoura bispina, Li, Weihai, Cui, Jianxin & Yang, Ding, 2017

Li, Weihai, Cui, Jianxin & Yang, Ding, 2017, Three new species of Mesonemoura (Plecoptera: Nemouridae) from China, Zootaxa 4272 (2), pp. 276-284 : 276-278

Mesonemoura bispina sp. nov.

( Figs. 1 , 4 , 5 )

Diagnosis. This species is characterized by the tergum IX being produced into a pair of large lobe-shaped, symmetrical paramedial protuberances ( Fig. 1 a) and by the median lobe of the paraproct forming a darkly sclerotized band ending in a bifurcate hook-like apex ( Figs. 1 a–b, 1f).

Adult habitus. ( Figs. 5 a, 5b) Males forewing length 7.2–7.4 mm, females forewing length 7.8–8.0 mm. General color dark brown. Head and pronotum dark brown to black; antennae dark brown, palpi brown. Thorax dark brown; legs: femora pale brown with diffused median brown band before dark brown distal third; tibiae basally brownish to brown darkened to distal portion, tarsi dark brown ( Fig. 4 a); wing membranes subhyaline, veins dark brown. Abdomen dark brown. Body coloration nearly black in older specimens.

Male terminalia. Tergum IX sclerotized, with wide shallow median indentation at anterior margin and two large paramedial lobe-shaped protuberances separated medially by a semicircular mid-posterior notch, protruding portion being covered by many tiny spines, the projecting area elevated and parallel-sided in lateral view ( Figs. 1 a, 1c). Sternum IX medially with hypoproct, basally wide and subquadrate, medially distinctly tapering toward tubular tip, anterior margin with claviform vesicle ( Fig. 1 b). Tergum X darkly sclerotized, with typical narrow median longitudinal below epiproct ( Fig. 1 a). Cercus slightly sclerotized, much longer than wide ( Figs. 1 a–1c). Epiproct has strongly sclerotized thin lateral bands at basal main portion, apical flagellum longer than dorsal sclerite, nearly parallel-sided except slightly tapering at the apex ( Figs. 1 a, 1c–1e). Paraproct with three well defined lobes: outer lobe mostly sclerotized with a dark lateral band, extended apically to a rounded tip, outer margin being surrounded by the inner part of spine-like median lobe; median lobe forms darkly sclerotized band, basally contacting the quadrate area of inner lobe, medially extended outward across outer lobe forming a bifurcate hook due to a smaller subapical spine; sclerotized inner lobe large and plate like, apex spine-like ( Fig. 1 f).

Female terminalia ( Figs. 1 g, 4b–4c). Sternum 7 with slightly sclerotized wide but short pregenital plate, plate covering anterior third of dark subgenital plate. Sternum 8 with heavily sclerotized subgenital plate, consisting of a pair of symmetrical subquadrate lateral sclerites separated by a wide posteromedial notch, the posterior margin of subgenital plate waved and somewhat cap-shaped, anterior portion extended backward under pregenital plate in paired erect horns. Vaginal lobe brownish and slightly sclerotized, with two well delimited large triangular sclerites, lateral and posterior margins sinuous and extended surrounding the subgenital plate, anterior extreme with lightly colored lateral caps. Inner genital sclerites via cuticular in ventral view with stout bowl-shaped anterior sclerite under sternum 7, nearly touching the anterior extension of the subgenital plate.

Sternum 9 sclerotized and brownish, with two triangular anterior extensions separated by an anterior indentation of the similar size as posterior notch of the subgenital plate.

Type Material. Holotype: Holotype male ( HIST), CHINA: Qinghai Province, Qinghai, Datong Hui and Tu Autonomous County, Baoku Nature Reserve, Daban Mountain , Chahan River , 2,880–3,100 m a.s.l., N 37°16.20' E 101°30.28', 15.VIII.2015, leg. Weihai Li . Paratypes: 3 males and 2 females (HIST), 2 males ( CAU), same data as holotype.

Distribution. This species is presently known from the type locality in Datong Hui and Tu Autonomous County of Qinghai Province. Daban Mountain is located on the southern piedmont portion of the Qilian Mountain Range. This species was collected with Amphinemura dabanshana Li, Du & Yang ( Li et al. 2017) in a similar habitat of the Chahan River, with two specimens found on riparian vegetation ( Fig. 5 c).

Etymology. The epithet refers to the bifurcate apex of the outer lobe of paraproct.

Remarks. The new species is most similar to M. lii Zhu, Yang and Yang, 2003 from Tibet in the general shape of the protuberances of tergum IX, but it may be easily separated from the latter by the bispined apex of outer paraproctal lobe in male and by the triangular vaginal lobe and the trapezoidal subgenital plate of the female.

The new species is also similar to two species known from southwestern Sichuan Province, M. sichuanensis Du and Ji, 2015 and M. spiroflagellata ( Wu, 1973) in the general shape of paraproct, but these two species have different mid-posterior protuberances of tergum IX.

Figures

FIGURE 1. Mesonemoura bispina sp. n. a – f, male. a. Terminalia, dorsal view; b. Terminalia, ventral view; c. Terminalia, lateral view; d. Epiproct, dorsal view. e. Epiproct, lateral view; f. Paraproct, caudal view; g. Female terminalia, ventral view.

FIGURE 4. Mesonemoura bispina sp. n. a. Legs, lateral view; b. Female terminalia, ventral view; c. Female terminalia, lateral view.

FIGURE 5. Mesonemoura bispina sp. n. a. Male adult, dorsal view. b. Female adult, dorsal view; c. Type locality, Chahan River.