Sweltsa bilobata Mo & Ye & Wang & Li 2020, sp. nov.
Creators: name: Mo, Raorao
name: Ye, Jianping
name: Wang, Guoquan
name: Li, Weihai
Publisher: name: Zenodo
Year: 2020
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Plecoptera
Chloroperlidae
Sweltsa
Sweltsa bilobata

description: Sweltsa bilobata sp. nov.
(Figs. 1-6)
Adult habitus (Figs. 1a, 1b, 3a, 3b). 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, 2a). 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, 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 d-2e, 3a, 4a, 4c-4d). Sternum 9 with broad trapezoidal subgenital plate, posterior margin truncate (Figs. 2c, 4b). 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 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 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, 4 a-4c, 4e-4h).
Female (Figs. 1b, 3b, 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, 3b). 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. Paratypes, 1 male and 1 female (HIST), same data and date as holotype.
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.
description: Published as part of 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, pp. 275-282 in Zootaxa 4853 (2) on pages 276-281, DOI: 10.11646/zootaxa.4853.2.8, http://zenodo.org/record/4519852