A New Remarkable Isoperla Species with Abdominal Processes from Hubei Province of Central China (Plecoptera: Perlodidae)

Zootaxa 4801 (3): 552–558 ISSN 1175-5326 (print edition) https://www.mapress.com/j/zt/ Article ZOOTAXA Copyright © 2020 Magnolia Press ISSN 1175-5334 (online edition) https://doi.org/10.11646/zootaxa.4801.3.7 http://zoobank.org/urn:lsid:zoobank.org:pub:2DC9800E-CC4D-4E66-B007-67A45AF8F8BB

A new remarkable Isoperla species with abdominal processes from Hubei Province of Central China (Plecoptera: Perlodidae)

QING-BO HUO1,2 & YU-ZHOU DU1,3,4* 1School of Horticulture and Plant Protection & Institute of Applied Entomology, Yangzhou University, Yangzhou 225009, China 2 [email protected]; https://orcid.org/0000-0001-9197-8503 3 [email protected]; https://orcid.org/0000-0002-4452-7125 4Joint International Research Laboratory of Agriculture and Agri-Product Safety, the Ministry of Education, Yangzhou University, Yangzhou 225009, China *Corresponding author

Abstract

A remarkable new species of Isoperla Banks, 1906, I. sextuberculata Huo & Du, sp. nov. from Hubei Province, Central China is described. The new species is distinguished by the unique paired abdominal processes on male terga 4, 7, and 8. The new species is compared to similar Isoperlinae congeners.

Key words: Isoperla, Kaszabia, new species, Isoperlinae, Plecoptera, China

Introduction

Isoperla Banks, 1906 is a genus with over 180 species known from the Holarctic Region (Banks 1906, Teslenko & Zhiltzova 2009, Judson & Nelson 2012, Sandberg & Kondratieff 2013, Szczytko & Kondratieff 2015, DeWalt et al. 2020). Only 14 species of Isoperla known from China, of which the type material of several species is either unavailable for study or briefly described with poor illustrations (Wu 1938, Yang & Yang 1996, Yang & Li 2018, Chen 2019). In this genus, most adult males do not have specialized tergal processes (Teslenko & Zhiltzova 2009, Judson & Nelson 2012, Szczytko & Kondratieff 2015), except for I. distincta Nelson, 1976, a species distributed in Smoky Mountain region of southeastern North America (Nelson 1976, Szczytko & Kondratieff 2015). Recently, we dis- covered another species of Isoperla from Shennongjia area, Hubei Province, Central China, of which also processed tergal processes and described it as new to science. The type locality, Shennongjia in Central China is a well-known biodiversity reserve with hundreds of wild animals and plants species (Ministry of Ecology and Environment of PRC 2020). Currently, more than fifteen species in five stonefly families (Chloroperlidae, Leuctridae, Nemouridae, Peltoperlidae and Perlidae) have been recorded from Hubei Province, and about half of them from Shennongjia (Du 1999, Yang et al. 2015). The discovery of this new species is also the first record of the family Perlodidae from Hubei Province.

Materials and methods

Specimens were collected by hand and are preserved in 75% ethanol. Abdominal segments of specimens were ex- amined and illustrated by KEYENCE VHX-5000. The holotype is deposited in the Insect Collection of Yangzhou University, Jiangsu Province, China.

552 Accepted by B. Kondratieff: 30 Apr. 2020; published: 19 Jun. 2020 Results

Isoperla sextuberculata Huo & Du, sp. nov.

General color yellowish to brown (Fig. 1). Head mostly yellowish except the areas between posterior ocelli to oc- ciput are darker brown. Triocellate, anterior ocellus smaller than posterior ones. Antennae and palpi dark brown. Pronotum disc yellowish laterally and dark brown medially; rugosities present medially (Fig. 2). Legs yellowish, tibia brown. Wings hyaline, veins dark brown (Fig. 1).

FIGURE 1. Isoperla sextuberculata sp. nov., male habitat.

FIGURE 2. Isoperla sextuberculata sp. nov., male, head and pronotum.

A REMARKABLE NEW ISOPERLA FROM CHINA Zootaxa 4801 (3) © 2020 Magnolia Press · 553 Male: Forewing length ca. 15 mm, hindwing length 13 mm, body length 13 mm. Abdomen brown and slightly sclerotized (Fig. 3). Terga 4–9 bearing a horizontal line of median erect hairs. A pair of hirsute processes presents on terga 4 (short and tuberculiform in shape), 7 and 8 (finger-like). Terga 5–6 with a pair of small lateral spots composed of darken setae (Figs. 3–4). Paraprocts short, triangular; membranous dorsally and slightly sclerotized ventrally, terminal upcurved and blunt (Fig. 5). Vesicle reduced as a dark spot on posterior margin of sternum 8, posterior margin with thicker median setae. Posterior margin of sternum 9 rounded (Fig. 6).

FIGURE 3. Isoperla sextuberculata sp. nov., male abdomen, dorsal view.

Female: Forewing length ca. 15 mm, hindwing length 13 mm, body length 15 mm. Body coloration similar to male. Subgenital plate broadly triangular, terminal bilobed with an obscure median notch (Fig. 7). Egg: Unknown. Nymph: Unknown. Type material: Holotype: ♂, China, Hubei Province, Shennongjia area, Guitouwan, 2150 m, 110°08.872′E, 31°28.439′N, 2011-V-25~28, leg. Li Ze-Jian (Insect Collection of Yangzhou University); Paratypes: 2 ♀♀, the same data and locality as the holotype (Insect Collection of Yangzhou University). Distribution: China, Hubei Province. Etymology: Name of the species refers to the six processes on male terga. Diagnosis: The abdominal processes of the new species are unlike any other known species of Asian Isoperla and species currently placed in Kaszabia Raušer, 1968 (Table 1). Unfortunately, it was not possible to examine the aedeagus of the single male, the holotype.

Discussion

The tergal processes of the adult male is not a unique feature in Isoperla and within the subfamily Isoperlinae. Similar processes occur in the Nearctic I. distincta and in the genus Kaszabia. Kaszabia includes two Asian species (DeWalt et al. 2020) that were originally placed in Isoperla, K. nigricauda (Navás, 1923) (Fig. 8A) known from Mongolia and Russia (Teslenko & Zhiltzova 2009, Judson & Nelson 2012) and K. digitata (Kawai, 1963) from Japan. Raušer (1968) and Zwick (1973, 2005) recognized K. spinulosa Raušer, 1968 as separate species (the holotype is a male), whereas Zhiltzova (1979), Teslenko & Zhiltzova (2009) and DeWalt et al. (2020) considered it as a synonym of K. nigricauda. Isoperla nigricauda was originally described from a female adult (Navás, 1923) and was recognized as occurring in China by Wu (1938) and Du (1999). Additionally, the specific validity of K. digitata has been questioned. Peter Zwick (personal communication) suspects that K. spinulosa is a junior subjective synonym of K. digitata. Unfortunately, the type material of I. digitata could not be located and may be lost (P. Zwick, personal communication). Maruyama & Hanada (2016) recently questioned the validity of Kaszabia, mentioning that another species of Isoperla (taxonomic status unclear) shares similar abdominal processes on male terga 5–7 (Fig. 8C).

FIGURE 6. Isoperla sextuberculata sp. nov., male abdomen, ventral view.

In summary, we are treating our new species as an Isoperla until a review of all existing material of those taxa with abdominal processes can be studied, including especially the completely everted aedeagi, mature eggs, and nymphs. We tentatively agree with Zwick & Surenkhorloo (2005) that species currently placed in Kaszabia prob- ably should be included in Isoperla.

FIGURE 8. Isoperlinae species with abdominal process. A: Kaszabia nigricauda; B: Isoperla distincta Nelson, 1976; C: Isop- erla sp. (A from Raušer 1968; B from Szczytko & Kondratieff 2015; C from Maruyama & Hanada 2016)

TABLE 1. A comparison between Isoperlinae species with abdominal process. Species Features of male abdominal process Distribution Position on terga Shapes Surface hair on process Isoperla distincta 5, 6 Tuberculiform Thick, apex only USA Isoperla sextuberculata 4, 7, 8 Tuberculiform/ Thick China fingerlike Isoperla sp. 5, 6, 7 fingerlike Unknown Japan Kaszabia digitata 3, 4 fingerlike Unknown Japan Kaszabia nigricauda 3, 4 fingerlike Sparse, apex only Mongolia, Russia

This project was supported by the National Natural Science Foundation of China (No. 31872266; 31071958). We express our gratitude to Drs. Peter Zwick (Schlitz, Germany) and Boris C. Kondratieff (Fort Collins, Colorado, U.S.A.) for providing suggestions that improved the manuscript. Dr. Sun Chang-Hai (Nanjing Agricultural Univer- sity) who generously shared the Japanese literature with us.

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