Research Article |
Corresponding author: Xiaoli Tong ( xtong@scau.edu.cn ) Academic editor: Ben Price
© 2021 Xianfu Li, Yanping Luo, Jian Jiang, Lili Wang, Xiaoli Tong.
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:
Li X, Luo Y, Jiang J, Wang L, Tong X (2021) Description of a new species of the genus Ameletus Eaton, 1885 (Ephemeroptera, Ameletidae) from Yunnan, China. ZooKeys 1021: 37-51. https://doi.org/10.3897/zookeys.1021.59927
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A new species with primitive characteristics, Ameletus daliensis Tong, sp. nov., is described, based on the morphology of imago, larva and egg with molecular data of the mitochondrial COI from Mount Cangshan, Dali, China. The new species is closely related to one of the most primitive mayflies, Ameletus primitivus Traver, 1939, by sharing persistent mouthparts in the alate stage, but it can be distinguished from the latter by the morphological differences of the mouthpart remains, wings and genitals in the imaginal stage. Both morphological and molecular evidence support that A. daliensis Tong, sp. nov. is a new member of the genus Ameletus. The discovery of the new species could help understand the origin and evolution of the genus Ameletus.
COI, integrative taxonomy, Kimura 2-parameter, Mayfly, southwest China
Ameletus Eaton, the largest genus of the family Ameletidae, is distributed in the Nearctic, Palearctic and Oriental Regions. The vast majority of the species of the genus are typical cold-water species and usually inhabit cold streams at mid-high latitude areas. Currently, Ameletus species are most diverse in the Nearctic Region with thirty-five species (
The specimens in this study were collected from Mount Cangshan, Dali City, Yunnan Province, China (Fig.
The larvae were collected with a D-frame net from two small streams (Heilong and Mocan) in Mt. Cangshan, some of the larvae were then directly placed into vials containing 90% ethanol in the field, the mature larvae with black wing pads were selected for transportation to artificial rearing cages in situ (Figs
Total genomic DNA was extracted from the legs of larva using the TIANamp Genomic DNA Kit (TIANGEN, Beijing, China) according to the manufacture’s protocol. The cytochrome c oxidase subunit I (COI) gene was amplified by the universal primers LCO1490-JJ/HCO2198-JJ to obtain a 658 bp fragment corresponding to the DNA barcoding region (
Holotype:
male mature larva (in ethanol, deposited in BMDU), China, Yunnan Province, Dali City, Mt. Cangshan, Mocan Stream (2020 m a.s.l.), 15.v.2020, coll. Xianfu Li. Paratypes (in ethanol, one male imago reared from larva and one larva are deposited in BMDU, the remaining in
Larva has the following combination of characters: 1) body with contrasting colour pattern; 2) labrum ventrally bordered with row of dense feathered setae (rare bi-forked setae) along anterior margin; 3) inner margin of trochanter in hind leg bearing row of brush-like fine and dense setae; 4) abdominal tergites I–X each with pointed spines on posterior margin; sternites without any spines on posterior margin, except V–VIII with tiny spines laterally; sternite IX with deep V-shaped cleft in both sexes. Sub-imago. 1) labial and maxillary palpi present and clearly visible; 2) wings semi-transparent, all cross-veins bordered around by dark brown. Imago. 1) labial and maxillary palpi present, but vestigial; 2) forewing transparent, MP2 turns downwards to meet CuA, stigmatic area suffused with milky and divided by a longitudinal vein; hind wings hyaline with short costal projection near the base; 3) genital forceps dark brown, apices of lobes round and slightly bent inwardly, ventral plates absent.
Mature larva
(in ethanol) (Figs
Head. Flagellum of antenna with approximately 15–17 segments. Labrum (Fig.
Larva of Ameletus daliensis Tong, sp. nov. 4 labrum (dorsal view) 5 right mandible 6 right maxillae 7 apex of terminal segment of maxillary palp (showing hook) 8 comb-shaped setae of maxilla (showing first seta) 9 labium 10 claw 11 hypopharynx (left: ventral view; right: dorsal view) 12 femur of foreleg 13–19 gills I–VII.
Thorax. Dorsal surface of legs covered with many minute spine-like setae; apices of femora with crosswise row of distinct stout spine-like setae (Fig.
Abdomen. Tergites I–X each with pointed spines on posterior margin (Figs
Male imago (in alcohol). Length (mm): Body 13 (12.5‒14.0); forewings 12 (11.5‒12.5); cerci 19 (16.0‒22.0).
Head. Upper portion of compound eyes grey, lower portion dark grey (Figs
Abdomen:
Tergites I and X brown, tergites II–IX brown with two triangle-like white markings on anterior half (Fig.
Genitals:
Styliger white with brown markings laterally (Fig.
Female subimago
(in alcohol). Length (mm): Body 13.5; forewings 13.5; cerci 11. Compound eyes dark grey. Lateral view of head, the labial and maxillary palpi present and clearly visible (Fig.
Eggs. Generally long ellipsoid shape with length 180‒205 μm and width 100‒115 μm (Fig.
The specific epithet is named after the type locality, Dali City, Yunnan Province, China.
China (Yunnan).
Larvae of this new species prefer to live in pools or slow currents with boulder and cobble substrate in very clear small streams. At one representative location (Heilong Stream, Mt. Cangshan) in May, the average water temperature was 14.6 °C, pH was 6.9 and DO (mg/l) was 7.6. Mature larvae with black wing-pads could be collected from early May through to mid-July, which suggests that the emergence period of the alate stage occurs from early May to late July, from which we infer that A. daliensis Tong, sp. nov. is a univoltine species in Dali, Yunnan. Before emergence, the mature larvae crawled to stones protruding from the water, half submerged and moulted to sub-imago (Fig.
A total of 71 COI sequences of Ameletus, which represent all sequenced species of the genus, including 24 unidentified species and 33 valid species, with four sequences from Ametropus neavei, Baetisca lacustris, Metreletus balcanicus and Siphlonurus quebcensis used as outgroups, were obtained from GenBank and BOLD for calculating genetic distances by K2P. The results showed that the interspecific genetic distances between A. daliensis sp. nov. and other sequenced Ameletus species are ranging from 5.5%–26.3%, of which the lowest K2P distance of 5.5% (Tables
Species | Collection locality | Collection date | GenBank Accession | Sources |
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Ameletus daliensis sp. nov. | Yunnan | 15 May 2020 | MW147549 | This study |
Ameletus sp.1 MT-2014 | Sichuan | 28 May 2012 | KM207086.1 |
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Ameletus sp.1 MT-2014 | Sichuan | 28 May 2012 | KM244682.1 |
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Pairwise genetic distances (COI) between Ameletus daliensis Tong, sp. nov. and Ameletus sp.1 MT-2014 using the Kimura 2-parameter.
The larvae of the new species are similar to Ameletus formosus Kang & Yang from Taiwan with a V-shaped cleft on the posterior margin of abdominal sternite IX, but it differs from the latter by: (1) anterior margin of labrum having a row of dense feathered setae (rarely bi-forked setae); (2) gills I–II much wider (width/length ratio is 0.66–0.71) than those of A. formosus and each gill bearing a short costal rib and (3) V-shaped cleft on sternite IX is much deeper and more acute than that of A. formosus. In addition, the trochanter of the hind leg of the new species in larvae bears a row of brush-like fine and dense setae (Fig.
This work was supported by the National Natural Science Foundation of China (U1602262, 31872265). Special thanks to Dr. Tiunova for providing helpful identification suggestions and literature and thanks are also due to Ronglong Yang and Zhen Tian (Dali University) for help with fieldwork and the referees for their advice and constructive comments.