Isoperla oncocauda Huo & Du 2018, sp. nov.
Creators: name: Huo, Qing-Bo
name: Du, Yu-Zhou
Publisher: name: Zenodo
Year: 2018
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Plecoptera
Perlodidae
Isoperla
Isoperla oncocauda

description: Isoperla oncocauda Huo & Du, sp. nov.
Male: Forewing length ca. 11.0 mm, hindwing length 10.5 mm, body length 10.0 mm. Head mostly dark brown, anterior ocellus slightly smaller, posterior ocelli closer to compound eyes than to each other; area between posterior ocelli to compound eyes yellow brown (Figs. 1–2). Antennae and palpi dark brown. Pronotum disc wider than long, black, lateral margins yellowbrown, rugosities present medially (Figs. 1–2). Legs yellow brown; wings hyaline, veins dark brown (Figs. 3–4). Abdomen dark brown and slightly sclerotized. Posterior margin of tergum 10 darkly sclerotized, recessed medially and rearward, extending as a process, with wide lateral grooves on surface, and perpendicular to tergum 10 posteriorly. Paraprocts sclerotized, blunt apically (Figs. 5). Vesicle reduced, slightly projecting beyond anterior margin of sternum 9 (Fig. 6). Anteromedially, sternum 9 yellowish-brown, membranous; posterior margin truncate (Figs. 6–10). Aedeagus membranous without conspicuous sclerites (Figs. 11–12) [partially everted]. In lateral view with one large dorsal lobe bearing few rows of spinules, one anterolateral lobe and three posteroapical lobes. Ventral surface covered with dense scale-like spines increasing in size toward base. A triangular membranous notch near the middle of anterior margin; nail-shaped spines before the notch increasing in size posteriorly.
Female: Forewing length 13.0 mm, hindwing length 11.5mm, body length 10.5 mm. Body coloration similar to male (Figs. 13–14). Abdomen brown, weakly sclerotized. Posterior margin of tergum 10 darkly sclerotized and extending as a process similar to male. Subgenital plate with basal sclerites laterally, broadly triangular, covering almost all of sternum 9, truncate apically with an obscure median notch (Figs. 15–18).
Egg: Unknown.
Nymph: Unknown.
Type material: Holotype: ♂, China, Zhejiang Province, Lin’an City, Tianmu Mountain Nature Reserve, Wuliting, 861m, 30°20.228′N, 119°26.136′E, 2018-IV-22, leg. Huo Qing-Bo, Gao Peng. Paratypes: 1♂, 2♀♀, similar coloration with the holotype; the same locality and data as holotype.
Etymology: The scientific name indicates the sclerotized developed process on the tergum 10 of the adult.
Discussion: Of the 14 known Chinese Isoperla species, the new species is apparently most similar to I. yangi Wu, 1935 described from Jiangxi Province of southeastern China. Currently, the male of new species can be distinguished by the shape of the vesicle. In I. yangi, the vesicle is well-developed and ovoid in shape (Wu 1938), where as in I. oncocauda the vesicle is reduced and only slightly projecting beyond anterior margin of 9 th sternum. The female apparently can be distinguished from all known Chinese Isoperla females by the posterior margin of tergum 10 extending as a process. Of 14 Chinese species, the male aedeagi of only two northern Chinese species, I. eximia Zapekina-Dulkeit, 1975 and I. lunigera (Klapálek, 1923) have been illustrated in part (Teslenko & Zhiltzova 2009). In both of these species, the aedeagus possess distinctive aedeagal sclerites.
The shallow stream of the type locality flows among the large rocks (Fig. 19). Adults were collected sitting on the rocks and from a nearby bridge.
description: Published as part of Huo, Qing-Bo & Du, Yu-Zhou, 2018, A new species of the genus Isoperla (Plecoptera: Perlodidae) from TIANMU MOUNTAIN NATURE RESERVE, China, pp. 276-284 in Zootaxa 4504 (2) on pages 277-282, DOI: 10.11646/zootaxa.4504.2.8, http://zenodo.org/record/2606285