Isoperla oncocauda Huo & Du, 2018

Huo, Qing-Bo & Du, Yu-Zhou, 2018, A new species of the genus Isoperla (Plecoptera: Perlodidae) from TIANMU MOUNTAIN NATURE RESERVE, China, Zootaxa 4504 (2), pp. 276-284 : 277-282

publication ID	https://doi.org/ 10.11646/zootaxa.4504.2.8
publication LSID	lsid:zoobank.org:pub:9AC935DB-B027-421A-AB13-5E275F976BAD
DOI	https://doi.org/10.5281/zenodo.5952446
persistent identifier	https://treatment.plazi.org/id/03B57A17-851A-A447-A1EC-372E6606FF78
treatment provided by	Plazi
scientific name	Isoperla oncocauda Huo & Du
status	sp. nov.

Treatment

Isoperla oncocauda Huo & Du View in CoL , 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 View FIGURES 1–2 ). Antennae and palpi dark brown. Pronotum disc wider than long, black, lateral margins yellowbrown, rugosities present medially ( Figs. 1–2 View FIGURES 1–2 ). Legs yellow brown; wings hyaline, veins dark brown ( Figs. 3–4 View FIGURES 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 View FIGURES 5–6 ). Vesicle reduced, slightly projecting beyond anterior margin of sternum 9 ( Fig. 6 View FIGURES 5–6 ). Anteromedially, sternum 9 yellowish-brown, membranous; posterior margin truncate ( Figs. 6–10 View FIGURES 5–6 View FIGURES 7–8 View FIGURES 9–10 ). Aedeagus membranous without conspicuous sclerites ( Figs. 11–12 View FIGURES 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 View FIGURES 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 View FIGURES 15–16 View FIGURES 17–18 ).

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 GoogleMaps . Paratypes: 1♂, 2♀♀, similar coloration with the holotype; the same locality and data as holotype GoogleMaps .

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 View FIGURE 19 ). Adults were collected sitting on the rocks and from a nearby bridge.