A study of Coeliccia cyanomelas Ris, 1912 (Odonata: Platycnemididiae)

Coeliccia cyanomelas is studied based on a large series of specimens from its whole distribution range. Intraspecies variations of color patterns on the thorax are discussed. Coeliccia sexmaculata Wang, 1994, Coeliccia mingxiensis Xu, 2006, and Coeliccia wilsoni Zhang & Huo, 2011 are all assigned as junior synonyms of Coeliccia cyanomelas. One ‘variety’ from Guizhou is reported and discussed briefly.

C. didyma (Selys, 1863) resembles C. cyanomelas in appearance, but is distributed further west (India, Peninsula Malaysia, and Thailand). Both Fraser (1933) and Asahina (1984) have mentioned that the first type specimen of C. didyma that Selys studied is from Tibet. Unfortunately, the abdomen end of this specimen is lost. Asahina (1984, p. 4) added that "This looks rather different bluish species resembled to C. cyanomelas Ris (Taiwan) with four pale spots on the front of pterothorax." He then cited Laidlaw's comment that Selys might have confused Tibet with Assam. Nobody knows why Asahina did not check the genital ligula of that specimen. The *Corresponding author. Email: lannysummer@163.com shape of the ligula in C. cyanomelas and C. didyma is completely different. We now can confirm that C. cyanomelas occurs in west Sichuan (Figure 1), an area used to be called Tibet (Yu & Bu, 2009). There are now no confirmed records of C. didyma from China. In any case, the didyma group (including C. didyma, C. cyanomelas, and maybe others) deserves a further study to test if the similar color pattern is phylogenetically meaningful.
The present study focused on the color variation of C. cyanomelas, synonymized three species, and reported a new 'variety'.

Remarks
According to our study, C. cyanomelas occurs in Anhui, Chongqing, Fujian, Gansu, Guangdong, Guangxi, Guizhou, Hainan, Henan, Hubei, Hunan, Jiangxi, Shaanxi, Sichuan, Taiwan, Yunnan, Zhejiang of China, and north Vietnam (Figure 1). Male color pattern of this species, especially on the thorax, shows large variations, which existed not only between but also within geographic populations. These variations may have led to a series of taxonomic mistakes (Yu, 2008). The  (Figure 2). SC has been used as an important diagnostic character in Wang (1994) and Xu (2006). However, it is not a creditable feature since the SC can either present or absent in individuals even within one population (Figure 3c, d). There is a similar situation for SS, which shows continuous variations from absent to quite large in Sichuan and Guangxi populations at least (Figure 3c, d). Few researchers previously have noted the variation of LE, although it is obvious. LE can be relative smooth like a straight line (Figures 2, 4a) or zigzag (Figure 3d-f) in different populations. Wang (1994) proposed C. sexmaculata mainly based on the presence of SC. However, we found this character to be quite common in populations of Henan, Gansu, Guangxi, Guizhou, and Sichuan (Figure 3d-h). Both cases (presence or absence of SC) can even appear in the same populations, e.g. Emeishan (Sichuan), Hechi (Guangxi) and Jinggangshan (Jiangxi) (Figure 3c, d). Another diagnostic character of C. sexmaculata is "the pale middle dorsal longitudinal stripe was continuous from S3 to S9" (Wang, 1994, p. 82). But the same character was also found in other populations, including Wenxian, Gansu. Furthermore, the first author XY has finally found the type specimens of C. sexmaculata from Shanghai Entomological Museum, Chinese Academy of Sciences (not the place Wang (1994) indicated). After checking the types, we confirmed that C. sexmaculata is a junior synonym of C. cyanomelas.  Xu (2006) proposed C. mingxiensis on the basis of a definite teneral male of Coeliccia species. According to his descriptions and figures, all characters of C. mingxiensis are identical to a teneral C. cyanomelas. Again, we have a large number of specimens covering the type locality of C. mingxiensis (Mingxi, located in Wuyi mountain, Fujian). After checking all these specimens (including some teneral ones) we believe that C. mingxiensis is just a junior synonym of C. cyanomelas. There is a long-standing confusion among Chinese workers about the teneral male color pattern of C. cyanomelas, which has even led to the irrelevant civil name "yellow stripe". Young males of C. cyanomelas always have an unusual but uniform yellow brown body color (Figure 3b, i), which becomes blue and decorated with a completely different pattern after maturing. Cuong, Thai, and Hong (2011) reported a new record of C. mingxiensis from Tam Dao National Park in north Vietnam. According to the photos of body and caudal appendages, the individuals they observed should all be teneral males of Coeliccia species (resemble cyanomelas), thus it is difficult to decide the exact species. If figures of genital ligula had been provided it would be helpful. Zhang & Huo (2011) published C. wilsoni on the basis of dry specimens collected in 2006, which had most probably had their blue body color decayed already (commonly in dry specimens of C. cyanomelas). According to wing vein and the 'fake' body color, Zhang thought this 'new species' is close to C. ryukyuensis, a completely different Japanese species. Generally, wing vein is not suitable for species level classification due to intraspecies variations caused by reasons such as fluctuating asymmetry (Hardersen, 2000). Zhang & Huo (2011) emphasized that the shape of genital ligula of C. wilsoni was different from C. cyanomelas. This was because they had not compared enough specimens from other populations. We have found continuous variations in the shape of genital ligula of C. cyanomelas (Figure 8). In terms of the color pattern of Coeliccia cyanomelas Ris, 1912 163  thorax and abdomen, as well as the shape of genital ligula, C. wilsoni should be the same species as C. cyanomelas. Furthermore, we have checked a series of specimens from the type locality (Nanzheng, Shaanxi) of C. wilsoni. Here we confirm that C. wilsoni should be a junior synonym of C. cyanomelas.

New variety
During fieldwork in Wengang, Libo, Guizhou we found an interesting little population of C. cyanomelas, of which the male color pattern is quite different from other populations (Figure 4g-i). The pale color on compound eyes is green anteriorly and blue posteriorly in life (Figures 2, 4 h) rather than wholly blue (Figures 3, 4a-f). Antehumeral stripes are small, similar size and shape to SS, pale blue with hint of green (Figure 4 g, h); those are definitely larger than SS and wholly blue in other populations (Figures 3c-h, 4a-f). Caudal appendages are wholly black (Figures 5 g, i, 7 g, i) rather than blue (Figures 5a-f, 7a-f). Head of genital ligula is triangular (Figure 8k, l) but shield-like in the sympatric general population as well as most other populations (Figure 8i, j). However, just as we have discussed above, the shape of genital ligula has obvious variations among populations, therefore we will not emphasize this character here. The same also happens to the shape of caudal appendages. For example, we still cannot find any distinct gaps in the shape variations of the male cercus, although the detailed structure of it is complicated (Figure 6). The more individuals are studied the more difficult is in determining diagnostic differences.
The Wengang population was restricted to a very limited habitat, viz. at the foot of a huge precipice about 1 km long. Males occurred in moderate density, but very few females were observed. No individuals from the sympatric general population (cf Figure 3f) were found within this range although they could be observed not far away. Preliminary molecular analysis (unpublished) showed that the Wengang population is not a distinct species. According to ICZN rules it cannot be a subspecies due to the sympatric distribution. We do not think it is a seasonal form either, since we are sure it will live simultaneously with the general population for quite a long time. Here we would like to treat this population as a Darwinian variety or incipient species which deserves further study.