Review of Phanoperla (Plecoptera, Perlidae) from China

Abstract Three Chinese species of the genus Phanoperla are reviewed. A new species, P.chenisp. nov., is proposed from Guangdong, southern China, and compared with related taxa. Neoperlopsbinodosa Wu, 1973 is confirmed from Hainan Province of China on the basis of re-examination of types from the island, but it is transferred to the genus Phanoperla and is placed as a synonym of P.pallipennis (Banks, 1938). A note on the distribution of the genus Phanoperla is also given.


Introduction
The perlid genus Phanoperla (subfamily Perlinae) was erected by Banks (1938) and is mainly distributed in the Oriental Region, with 52 species worldwide (DeWalt et al. 2021). In China, the first description of a Phanoperla species was based on specimens from Hainan Province by Banks (1938). After nearly a century, Li and Qin (2016) described P. hainana Li & Qin, 2016, the second Chinese species of the genus, also from Hainan. And recently, Phanoperla huanghuye Chen, 2020 was shown to be a member of Neoperlops (Mo et al. 2020). During a collecting tour in the Nanling Mountains in September 2020, additional important material was collected from Chebaling National Natural Reserve of northern Guangdong Province, China, and it is described as new: P. cheni sp. nov. In addition, Neoperlops binodosa Wu, 1973 is herein considered a member of the genus Phanoperla and placed in the synonymy of P. pallipennis (Banks, 1938). In the present paper, a review of Chinese Phanoperla and a distribution map of the genus Phanoperla are presented.

Materials and methods
The holotype of Phanoperla cheni sp. nov. was collected using a sweep net and is deposited in the Henan Institute of Science and Technology, Xinxiang (HIST). Types of Neoperlops binodosa Wu, 1973 are deposited in the National Zoological Museum of China, Institute of Zoology, Chinese Academy of Sciences, Beijing (IZCAS). The studied materials are stored in 75% ethanol. The holotype of Phanoperla cheni sp. nov. was examined with the aid of an Olympus SZ61 dissecting microscope, and color photographs were made with Keyence VHX-S650E and Leica M420 microscopes. The color photographs of Neoperlops binodosa Wu, 1973 were made with a Leica C camera with a lens of an Olympus SZX7 microscope in the IZCAS. Terminalia were removed from the abdomen and soaked in 10% NaOH. The aedeagus was everted using the cold maceration technique of Zwick (1983). Morphological terminology primarily follows that of Zwick (1982). The map (Fig. 7) was prepared using a base map downloaded from the standard map service of the online government service platform of the Ministry of Natural Resources, People's Republic of China (http://bzdt.ch.mnr.gov.cn/; map number GS(2016)2938).
Aedeagus (Figs 3,4). Aedeagal envelope membranous with a large ventral patch of spinules. Aedeagal tube short, S-shaped in lateral aspect and dorsally expanded at apex: dorsal sclerite slender, band-shaped; basal surface with two ventrolateral groups of tiny spines; apical half fully covered with stout spines. Aedeagal sac as long as tube, curved ventrad, mostly covered with brown spines, but base bare: a pair of lateral black spine patches located in ventral surface of median half; apical half with a scarf-shaped band of larger black spines; apical part tubular, fully armed with tiny golden-brown spines.  Etymology. The patronym honors the collector of the holotype; a noun (name) in genitive case.
Distribution. China (Guangdong Province). The new species is known only from the Chebaling National Natural Reserve of Guangdong, which is in the Nanling Mountains. The Reserve has a subtropical monsoon climate, with heat and abundant rainfall throughout the year.
Remarks. The male genitalia and aedeagal tube of the new species is similar to that of P. wieng Sivec & Stark, 2010 from Phrae Province of Thailand. However, in that  fig. 39-41). In addition, the aedeagal sac of P. wieng bears a dorsomedian hump and a pair of dorsobasal lobes, which are lacking in the straight aedeagal sac of the new species. Both species bear a similar spine arrangement of the aedeagal sac, but in the new species, a pair of small patches of black spines are present on the ventrolateral surface of the median half of the aedeagal sac, while the spine patches are lacking in P. wieng. The new species is also similar to P. vietnamensis Zwick, 1986 in its male terminalia, but their aedeagi are obviously different (compare Zwick 1986: figs 2, 3 with Figs 3, 4). In addition, the new species lacks two irregular rows of sensilla on tergum 9.

Distribution. China (Hainan Province).
Remarks. This species is a member of the Phanoperla pallipennis species group (Zwick 1982) and was described on the basis of the male holotype from Mount Limushan, which is located in Qiongzhong County, central Hainan Province (Li and Qin 2016). This species can be distinguished from all other Chinese species of Phanoperla by the unique head pattern and different aedeagus.
Diagnosis and remarks. Neoperlops binodosa Wu, 1973 was transferred to Neoperla by Du et al. (1999), but its status is still questionable because of the unknown male aedeagus (Du et al. 1999;Yang and Li 2018). We transfer N. binodosa to Phanoperla and synonymize it with P. pallipennis (Banks, 1938) on the basis of the identical male terminalia and main aedeagal armatures (compare Zwick 1982: fig. 10a, d with Fig. 5). The subgenital plate of female specimens agrees well with the original description and figures by Wu (1973), being scarcely produced and without an apical notch (Fig. 6), which differs from the female paratypes of P. pallipennis. Therefore, we propose that female specimens in IZCAS may be not conspecific with male specimens and may even not belong to the genus Phanoperla. The female subgenital plate of Phanoperla is usually slightly produced and typically bilobed, with a sausage-like or balloon-like spermatheca (Sivec et al. 1988; Cao and Bae 2009). Consequently, we boldly postulate that   Banks, 1938. this female is Neoperla sp., because of the barely produced subgenital plate and a coiled spermatheca which is common in Neoperla. Unfortunately, the female specimens in the IZCAS are badly damaged and should be confirmed by new studies.

Concluding remarks
The genus Phanoperla currently consists of 52 valid species and is restricted to the Oriental Region (Fig. 7), mostly occurring in the Indonesian archipelago and Thailand (DeWalt et al. 2021). The wide distribution of Phanoperla in the Oriental Region, which covers nearly two-thirds of the region, suggests that more species will be found there, even in areas where the genus is unreported, such as the western of part the Himalayan region, Bangladesh, Myanmar, Laos, and southwest and south China.
The major references dealing with Chinese Phanoperla are Banks (1938) and Li and Qin (2016); these include only with two species: P. hainana Li & Qin, 2016 and P. pallipennis (Banks, 1938), both occurring in Hainan Province of southern China. Neoperlops huanghuye (Chen, 2020), from Fujian Province, was placed in Phanoperla in a previous study but was re-evaluated to belong to Neoperlops on the basis of the male and female terminalia, aedeagus, and eggs (Mo et al. 2020). In this study, the third Phanoperla species from China, P. cheni sp. nov., is described from Guangdong Province, which faces Hainan across the South China Sea. And Neoperlops binodosa Wu, 1973, a synonym of P. pallipennis, was known from Hainan and Yunnan provinces (Wu 1973), but as the Yunnan paratype was not found and the allotype proved to belong to another species, presence in Yunnan must still be confirmed.