Sweltsa bilobata, Mo & Ye & Wang & Li, 2020

Mo, Raorao, Ye, Jianping, Wang, Guoquan & Li, Weihai, 2020, The first record of the family Chloroperlidae (Plecoptera) from the Guangxi Zhuang Autonomous Region of southern China, with description of a new species of Sweltsa Ricker, 1943, Zootaxa 4853 (2), pp. 275-282 : 276-281

publication ID	https://doi.org/ 10.11646/zootaxa.4853.2.8
publication LSID	lsid:zoobank.org:pub:EFC3ECB6-BE34-463E-9979-132A1392FF60
DOI	https://doi.org/10.5281/zenodo.4519888
persistent identifier	https://treatment.plazi.org/id/03C187A9-5606-7E7F-15B5-9916C9CD76FB
treatment provided by	Plazi
scientific name	Sweltsa bilobata
status	sp. nov.

Treatment

Sweltsa bilobata View in CoL sp. nov.

( Figs. 1-6 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5 View FIGURE 6 )

Adult habitus ( Figs. 1a, 1b View FIGURE 1 , 3a, 3b View FIGURE 3 ). General color greenish, becoming pale in ethanol. Head with a large, rectangular median dark area; compound eyes dark, ocelli with dark rings; antennae pale but distal flagella brown ( Figs. 1a View FIGURE 1 , 2a View FIGURE 2 ). Pronotum with brown symmetrical medial pattern. Wing membrane transparent; legs pale. Abdominal terga 1-7 with median brown triangular stripe, tergum 8 with median brown elliptical stripe. Cerci pale with long setae.

Male ( Figs. 1a View FIGURE 1 , 2 View FIGURE 2 a-2e, 3a, 4a–4h, 6a, 6b). Body length 8.1-8.3 mm (from head excluding antennae to tip of forewing); forewing length 7.0- 7.2 mm; hindwing length 5.8-6.0 mm. Lateral hair brush typical, present at abdominal segments 6-9. Tergum 9 sclerotized except medial portion membranous, transverse ridge strongly sclerotized and band-shaped, the ridge in lateral aspect forming triangular process ( Figs. 2b, 2 View FIGURE 2 d-2e, 3a, 4a, 4c-4d). Sternum 9 with broad trapezoidal subgenital plate, posterior margin truncate ( Figs. 2c View FIGURE 2 , 4b View FIGURE 4 ). Tergum 10 with a pair of distinctly sclerotized transverse lateral bands, the medial portion between the bands greatly enlarged in the shield-like darkly sclerotized basal anchor, the anchor slightly wider than long, and with typical membranous groove and paragential plates between hemiterga, basal bar concave ventrally and abruptly up-curved dorsad medially, thus L-shaped in lateral view ( Figs. 2b, 2 View FIGURE 2 d-2e, 3a, 4a, 4c,4d). Epiproct claviform, parallel-sided for its most length, but slightly constricted medially, subapically tapering to a sharp tip in dorsal view; in lateral view, ventroapical half moderately enlarged and flat, dorsal subapical portion with a indistinct notch and the tip rounded ( Figs. 2b, 2 View FIGURE 2 d-2e, 3a, 4a, 4c, 4d, 6a, 6b). Aedeagus membranous, trapezoidal in ventral aspect, with a pair of finger-like apical lobes and a flat semicircular dorsoapical lobe ( Figs. 2c View FIGURE 2 , 4 View FIGURE 4 a-4c, 4e-4h).

Female ( Figs. 1b View FIGURE 1 , 3b View FIGURE 3 , 5 View FIGURE 5 a-5d). Body length ca. 11.2 mm (from head excluding antennae to tip of forewing); forewing length ca. 9.3 mm; hindwing length ca. 8.0 mm. Habitus generally similar to male except only female abdominal terga 1-7 with median brown subtriangular stripe ( Figs. 1b View FIGURE 1 , 3b View FIGURE 3 ). The posterior margin of sternum 8 forming a large trapezoidal subgenital plate, reaching near posterior margin of sternum 9 and expanding in lateral view seems scalloped, with a small triangular posteromedial notch.

Type Material. Holotype male ( HIST), CHINA: Guangxi Zhuang Autonomous Region, Guilin City , Xing’an County, Maoershan National Natural Reserve , Jiuniutang , E 110°25’1”, N 25°52’16’’, 1961-2000 m, 2020.VI.22, Mo R. R., Yang Q.C. et al GoogleMaps . Paratypes, 1 male and 1 female ( HIST), same data and date as holotype GoogleMaps .

Etymology. The name refers to a pair of finger-like apical lobes of the aedeagus. Latin “bi-” means two, double, and “lobus” means lobes.

Distribution. China (Guangxi Zhuang Autonomous Region).

Remarks. The new species is similar to the Indian species, S. assam Zwick, 1971 in sharing the similar head pattern, tergum 9, the dorsal shape of the epiproct and general shape of female subgenital plate. However, S. bilobata may be easily separated from S. assam by the following features: pronotum with larger brown medial pattern, dorsal aspect of epiproct nearly straight in lateral view. In S. assam , the pronotum bears a narrow pale brown medial pattern; apical half of the epiproct has a noticeable subapical indentation and seemingly downcurved in lateral view (figs. a & d in Zwick 1971).

In addition, the head pattern, tergum 9 and the general shape of epiproct of the new species is also similar to S. longistyla ( Wu, 1938) from China. However, in S. longistyla , the medial pattern of pronotum is narrower; the epiproct is slender and stiletto-shaped, gradually tapering to apex with a blunter apical point, and ventroapical half is not enlarged; basal anchor is small and cup-like; the female subgenital plate is smaller and triangular with apex larger rounded medial notch (figs. 14-27 in Li et al. 2014), not as in S. bilobata , the medial pattern of pronotum is wider; epiproct is claviform, mostly parallel-sided except for medial constriction, and only subapically tapering toward tip with sharper apex in dorsal view; ventroapical half is obviously enlarged in lateral view; basal anchor is larger and shield-like. Additionally, usually the females of most Sweltsa species have notched subgenital plates. The female subgenital plate of new species is broader and trapezoidal with a small triangular posteromedial notch, which is helpful separating females of the two species.