Nemoura cucurbitata, Mo & Wang & Yang & Li, 2020

Mo, Raorao, Wang, Guoquan, Yang, Ding & Li, Weihai, 2020, Nemoura cucurbitata (Plecoptera: Nemouridae), a new stonefly species from Guangxi, China, Zootaxa 4731 (1), pp. 145-150 : 145-148

Nemoura cucurbitata sp. nov.

( Figs. 1–3 )

Adult habitus. Head and mouthparts black; antennae and palpi brown; compound eyes black. Pronotum dark brown, rectangular, corners nearly right-angled with cuticular rugosities. Legs uniformly brown; wings brownish, subhyaline with dark veins. Abdominal segments brown but terminalia darker with hairs pale brown.

Male ( Figs. 1–3 ). Forewing length ca. 5.4 mm. Hindwing length ca. 4.6 mm. Tergum 9 ( Figs. 1 b–1c) distinctly sclerotized but median area weakly sclerotized, middle of distal margin nearly extended to anterior margin of tergum 10, forming a round membranous projection, with a shallow mid-anterior incision and with three long spine extending to anterior margin of tergum 10 at mid-posterior portion. Sternum 9 ( Fig. 1d ) with claviform vesicle, length ca. 3X maximum width, slightly constricted basally; hypoproct broad and rectangular, gradually tapering subapically toward short, nipple-like apex. Tergum 10 ( Figs. 1 b–1c) mostly sclerotized, with a triangular sclerite plate and narrow longitudinal concavity beneath epiproct; anterior and mesolateral part bears several tiny black spines, two stout black spines located on basal half of left long heavily sclerotized band and membranous area of right lateral part, respectively. Cercus distinctly sclerotized, longer than wide and gradually tapered toward tip but abruptly tapered subapically forming a stout spine at apex ( Figs. 1 b–1d, 3c–3d). Epiproct ( Figs. 1 b–1c, 2): gourd-shaped, curved backward, the apical half distinctly up-curved, near 2X longer than width in the middle of the length, with a long, pointed apex; constricted posteriorly from midlength, becoming wider laterally. Dorsal sclerite loop-shaped but interrupted medially at apex, membranous with a pair of heavily sclerotized lateral sclerites dorsolaterally; becoming narrow around heavily sclerotized lateral knobs. Basal cushion larger than dorsal one, trapezoidal, bears a large triangular sclerotized sclerite which is extending to lateral knobs. Basal sclerites large, darkly sclerotized, narrowed to posterior margin of the epiproct. Ventral sclerite heavily sclerotized, broad at basal half, with lateral knobs at basolateral corners, two pairs of pointed apical prongs in ridges and a pair of pointed apical sclerites, becoming narrower toward middle part and inserting into the fold of dorsal sclerite. Ventral sclerite apically developed in a pair of rounded anteriorly and triangular posteriorly, forming a ring in dorsal view; ring interrupted dorsomedially with rounded edges and slightly covered dorsal sclerite anteriorly, and surrounded apical sclerites. Paraproct ( Figs. 1 b–1d, 3a–3b) divided into two lobes: outer lobe, subtriangular, strongly sclerotized along outer margin forming a black, acute hook curved upward at apex; inner lobe short and narrow, broad at base, slightly sclerotized, apical half spindly with sharp tip.

Female. Unknown.

Type material. Holotype: 1 male ( HIST), China: Guangxi Zhuang Autonomous Region, Guilin City , Xing’an County, Tongrencun , Maoershan National Natural Reserve , 1873.0 m, 25.905º N, 110.440º E, 2017.VII.30, Raorao Mo , Yeyun Zhao.

Etymology. The name refers to the gourd-shaped epiproct. The Latin “ cucurbitata ” means gourd.

Distribution. China (Guangxi Zhuang Autonomous Region).

Remarks. The new species belongs to the N. ovocercia complex of Baumann (1975) sharing an apical stout spine on the enlarged cerci. The unique gourd-shape epiproct distinguishes the new species from species of the complex, and apparently from all other known species of Nemoura . The outer paraproct lobe of N. cucurbitata bears a slender and strongly curved inward spine that is similar to the Vietnamese N. clavaloba Sivec & Stark, 2010 , N. tenuiloba Sivec & Stark, 2010 , and the Thai N. raptoraloba Sivec & Stark, 2010 , but N. cucurbitata is easily separated from the above species by the long and pointed apical sclerite of the epiproct.

Figures

FIGURE 1. Nemoura cucurbitata sp. nov. (male). a. Head and pronotum, dorsal view. b. Terminalia, dorsal view. c. Terminalia, dorsal view. d. Terminalia, ventral view.

FIGURE 2. Nemoura cucurbitata sp. nov. (male). a. Epiproct before cleared, dorsal view. b. Epiproct after cleared, dorsal view. c. Epiproct after cleared, oblique lateral view. d. Epiproct after cleared, dorsal view. e. Epiproct after cleared, ventral view. f. Epiproct after cleared, lateral view. g. Epiproct after cleared, oblique lateral view.

FIGURE 3. Nemoura cucurbitata sp. nov. (male). a. Left paraproct, ventral view. b. Top of outer lobe of left paraproct, caudal view. c. Tip of left cercus, caudal view. d. Left cercus, lateral view.