Megalestes micans Needham, 1930

Yu, Xin & Xue, Junli, 2020, A review of the damselfly genus Megalestes Selys, 1862 (Insecta: Odonata Zygoptera: Synlestidae) using integrative taxonomic methods, Zootaxa 4851 (2), pp. 245-270 : 262

Megalestes micans Needham, 1930

( Figs. 3 k–l; 4k–l; 5i, m, w–x, ab; 6i–j)

Megalestes micans Needham, 1930: 230–231 [Sichuan]; Asahina 1985b: 8–10; Karube 2014: 73, fig. 1 [Sapa, Lao Cai, Vietnam]; Phan & To 2018: 1–6, figs. 1–3, 10–11, 19–21 [Hoang Lien National Park, Lao Cai, Vietnam].

Megalestes chengi Chao, 1947: 15–25 , figs. 2, 4, 6, 8, 10–11, 14, 16–17, 21; Chao 1965: 190–191; Asahina 1985b: 9–12. Syn. nov.

Megalestes discus Wilson, 2004: 424–427 , figs. 4–8, [Mangshan, Hunan, China]; Wilson & Xu 2007: 102–103, “Nanling, Guangdong,” key to species. Syn. nov.

Megalestes raychoudhurii Lahiri, 1987: 54–56 , figs. 131–132, 298–299, 519 [Meghalaya, India]. Syn. nov.

Megalestes irma [nec. Fraser, 1926]: Gyeltshen et al., 2017: 588–594, fig. 4e–f [ Bhutan].

This is the most widespread species of Megalestes , occurring throughout South China (Fujian, Guangdong, Guangxi, Guizhou, Henan, Hunan, Jiangxi, Sichuan, Yunnan, and Zhejiang) extending to Vietnam, Bhutan, and India. It is also the only species distributed on both sides of the Himalayas. The diagnostic character for this mid-sized species is the base of the basal tooth on the paraproct bulged, covered in dense setae ( Fig. 6 i-j). This species is closely related to M. riccii , and this was confirmed by molecular analysis ( Fig. 7 ).

In the description of M. chengi, Chao (1947) only compared his material with M. heros , a totally different species. Later, Chao (1965) stated that the differences between M. chengi and M. micans included the middle portion of the middle lobe of the pronotum green, not yellow (feature 2), and the base of the basal tooth of the paraproct slightly, but not greatly, bulged (feature 15). However, all these characters occur in intraspecies variation (Discussion section). Although both Chao (1965) and Asahina (1985b) have emphasized that M. chengi was very similar to M. micans , neither author confirmed that they are really the same species. We examined eight of the type specimens of M. chengi deposited in IZAS and IEAS including the holotype and found no evident morphological differences with M. micans . The molecular analyses also suggested that these two are the same species ( Fig. 7 ). Therefore, based on both morphological and molecular evidence ( Fig. 8 ), we confirm that M. chengi is a junior synonym of M. micans .

As we have previously discussed, diagnostic characters of M. discus cannot separate it from M. micans . Wilson & Xu (2007) mentioned that M. discus have “inferior appendages without a basal pair of stout spines or robust teeth,” which is incorrect, and “occipital margin with/without transverse yellow spot” (feature 1) supports our opinion that this character is not stable. We examined the diagnostic character photos of the paratype of discus (1 m #, Mangshan (near Babaoshan), Shikengkong, S Hunan, China, 26-VI-2000, K.D.P. Wilson leg.), which were kindly sent by K. D. P. Wilson, and found that all the characters are consistent with M. micans . No further information on M. raychoudhurii has been published after its original description. According to the features of caudal appendages and genital ligula in the original description and figures, there is no difference between M. raychoudhurii and M. micans . We believe that both discus and M. raychoudhurii are junior synonyms of M. micans .

Figures

FIGURE 3. Caudal appendages of males (dorsal view). a) australis; b) irma, paratype; c) distans, from Yaan, Sichuan; d) distans from Dashahe, Guizhou; e) heros; f) omeiensis, paratype; g) kurahashii; h) major; i) haui; j) “palaceus”; k) micans, bd: basal disk; l) “chengi”; m) riccii; n) “maai”; o) “tuska,” from Damingshan, Guangxi; p) “tuska,” from Jinxiu, Guangxi. (Scale bar = 0.5 mm).

FIGURE 6. Line drawing of male paraprocts (lateral view). a) australis; b) distans; c) gyalsey; d) kurahashii; e) major; f) haui; g) heros; h) omeiensis; i) micans; j) micans; k) riccii; l) irma.

FIGURE 7. Phylogenetic reconstruction from ITS data modified based on BI and ML trees, with both posterior probabilities (right) and bootstrap values (left) shown.

FIGURE 8. Molecular and morphology-based species delimitation of Megalestes. M: morphological character method; lg: genital ligula; app: caudal appendages, including cerci and paraprocts; GD: genetic distance; TC: traditional classification.