Research Article |
Corresponding author: Xian-Fu Li ( lixf@eastern-himalaya.cn ) Academic editor: Eduardo Dominguez
© 2023 Kun Yang, Xian-Fu Li, Xiao-Li Tong, Qing-Hua Cai.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Yang K, Li X-F, Tong X-L, Cai Q-H (2023) A new species of Siphlonurus Eaton, 1868 (Ephemeroptera, Siphlonuridae) from Yunnan, China. ZooKeys 1166: 121-139. https://doi.org/10.3897/zookeys.1166.102847
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Siphlonurus dongxi Li & Tong, sp. nov. from Shangri-La City, Yunnan Province, China, is described based on egg, nymph, and winged stages. The new species is closely related to S. davidi (Navás, 1932), and can be distinguished by the colour of the imago, the forking point of MP, the penis, posterolateral spines of tergum IX of imagoes, and first abdominal terga nymph, as well as the structure of the egg. The new species and S. davidi have the same morphological and structural characteristics, such as the long cubital area with many intercalaries, cross veins between C, Sc, RA, and RSa1 surrounded with distinct pigments, the strong curvature of vein CuP in the forewing, the broad expansion of the hindwing, the membranous penis lobes fused without teeth, supporting the proposition of a new species complex, the Siphlonurus davidi group. The structures of the penis and the egg of the new species could help understand the origin and evolution of the genus Siphlonurus.
Hengduan Mountains, Himalaya, Mayfly, Siphlonuridae
The genus Siphlonurus Eaton, 1868 (Ephemeroptera, Siphlonuridae) is characterized by many plesiomorphies (
Siphlonurus davidi presents some plesiomorphies, indicating a close relationship with the ancestor of the Siphlonurus lineage, such as the forking point of MP subequal to that of the fusion point of MA and RS, the cubital area longer and with more intercalaries between CuA and the posterior margin of the wing, and the hindwings approximately half the length of the forewings, longer than in other Siphlonurus species (
Siphlonurus nymphs were collected with a D-frame net from the floodplain habitats of the Dugang River in Shangri-La City, northwestern Yunnan, China. Following the guidelines from
All examined materials were deposited at the Museum of Biology, Institute of Eastern-Himalaya Biodiversity Research, Dali University, Dali, Yunnan, China (MBDU).
Holotype : male imago, with final nymphal instar exuvia (in ethanol), China, Yunnan Province, Shangri-La City, Jiantang Town, Dugang river, 27°47′50.4″N, 99°48′43.3″E, 3361 m a.s.l., 12.VI.2022, coll. Xian-Fu Li. Paratypes: 13 nymphs, 30 imagoes and 8 subimagoes reared from nymphs with same data as holotype. 5 nymphs from same location as holotype, but 1.VI.2021, coll. Yi-Hao Fang.
The new species is similar to S. davidi. It can be distinguished from S. davidi by the colour of the imago, the morphological structure of egg, the forking point of MP, the transversal sclerite of the penis with two dorsal elongations, the dorsal elongation of the penis basally expanded, the elongations of the ventral sclerite, the posterolateral spines of tergum IX of imagoes and the first abdominal terga of the nymph, as well as the structure of the egg.
Male imago (in ethanol). Body length 18.4–20.5 mm (excluding cerci), head width 3.3–3.5 mm, forewing length 17.3–18.6 mm, hindwing length 7.8–8.1 mm, antennae 1.4–1.6 mm. Ratio of hindwing: forewing length about 0.43.
Head
: compound eyes contiguous (Fig.
Thorax
: generally light yellow and dark brown, mesonotum anterior and legs basal with light yellowish stripes or rings (Figs
Abdomen
(Fig.
Genitalia. Penis relatively long (Fig.
Male subimago
(in ethanol) (Fig.
Female imago
(in ethanol). Colour pattern similar to male; body length 19.6–22.2 mm, head width 3.1–3.4 mm, caudal filaments 20.7–24.4 mm, forewing 18.5–21.3 mm, hindwing 9.0–9.4 mm (Fig.
Female subimago
(in alcohol). Similar to male subimago except the tarsal segments of foreleg with more spines and usual sexual differences (Figs
Winged stages of Siphlonurus dongxi Li & Tong, sp. nov. (living) are shown in Fig.
Eggs.
Oval with irregular flat areas (Fig.
The new species presents persistent mouthparts in winged stages; in ventral view of head, the labial and maxillary are present and clearly visible (Fig.
(in ethanol) light yellow with red and dark markings (Fig.
The specific epithet dongxi, is named after the Chinese abbreviation of the Institute of Eastern-Himalaya Biodiversity Research, Dali University (https://www.eastern-himalaya.com.cn/contents/16/923.html). We hope that the Institute of Eastern-Himalaya Biodiversity Research can become an important platform for biodiversity research in the world. At the same time, we hope to cooperate with scientists from all countries through the International Centre of Biodiversity and Primate Conservation (http://www.icbpc.org/index.html).
China (Yunnan).
Nymphs of this new species prefer to live in pools or slow current areas with aquatic plants close to the bank in clear, high-altitude, wide streams (Fig.
The identification key of three Asian Siphlonurus species, S. binotatus Eaton, 1892 (
Siphlonurus dongxi Li & Tong, sp. nov. is closely related to S. davidi, whose adults share the markings of the wings, the strong curvature of vein CuP, the broad expansion of the hind wing, the longer cubital area in the forewing, and the membranous penis lobes fused without teeth. Siphlonurus dongxi Li & Tong, sp. nov. and S. davidi differ from all other described Siphlonurus species in these characters (
There are significant differences within the Siphlonurus davidi group, such as the following characters:
These numerous and significant differences between S. dongxi Li & Tong, sp. nov. and S. davidi suggest that the existence of a species bridging the gap between them is possible.
Obviously, the new species shows characteristics that fall somewhere between S. davidi and other ones. The discovery of this new species bridges the gap between S. davidi and other Siphlonurus species, and could help reveal the origin and evolution of the genus Siphlonurus.
This work was supported by the Second Tibetan Plateau Scientific Expedition and Research Program (2019QZKK0402) and the National Natural Science Foundation of China (31960255). Thanks are due to Yi-Hao Fang (Dali University) for help with fieldwork. We are grateful to Michel Sartori (Museum of Zoology, Lausanne, Switzerland), an anonymous reviewer, and Davide Fornacca (Dali University) for their useful suggestions and corrections that improved the quality of the manuscript.
No conflict of interest was declared.
No ethical statement was reported.
The Second Tibetan Plateau Scientific Expedition and Research Program (2019QZKK0402) and the National Natural Science Foundation of China (31960255).
Kun Yang: Writing - Original Draft; Xian-Fu Li: Conceptualization, Methodology, Writing - Review & Editing; Xiao-Li Tong: Writing - Review & Editing; Qing-Hua Cai: Project administration, Funding acquisition.
Xian-Fu Li https://orcid.org/0000-0002-1258-1573
All of the data that support the findings of this study are available in the main text or Supplementary Information.