Bayadera hyalina Selys, 1879

Phan, Quoc Toan, Kompier, Tom, Karube, Haruki & Hayashi, Fumio, 2018, A synopsis of the Euphaeidae (Odonata: Zygoptera) of Vietnam, with descriptions of two new species of Euphaea, Zootaxa 4375 (2), pp. 151-190 : 161-162

Bayadera hyalina Selys, 1879 (supposition)

( Fig. 7a–h )

Bayadera hyalina: Selys (1879) , p. 27; Needham (1909), p. 191; Laidlaw (1917), p. 31; Fraser (1928), pp. 52–53, Fig. 5 ; Fraser (1934), p. 81; Lahiri (1975), p. 255; Davies & Tobin (1984), pp. 22–23; Lahiri (1987), pp. 37–38, Figs 81–82, 117–118; Donnelly (1994), p. 86; Hämäläinen & Pinratana (1999), p.8; Hämäläinen (2017), p. 9; Zhang (2017), 45 (species list).

Materials examined. [ Vietnam] 1♂, Tu Le , Yen Bai Prov., 25.V.2015, T. Kompier leg. (TKC) ; 1♂ 1♀, Tu Le , Yen Bai Prov., 30.VI.2015, T. Kompier leg. (TKC) ; 1♂, Tu Le , Yen Bai Prov., 11.V.2014, T. Kompier leg. (TKC) ; 1♂, Tu Le , Yen Bai Prov., 11.VII.2015, T. Kompier leg. (TKC) ; 1♂, Tu Le , Yen Bai Prov., 16.IX.2015, Q.T. Phan leg. ( PQTC) ; 1♂, Lai Chau Prov., 17.IV.2014, T. Kompier leg. (TKC) ; 1♂, Hoang Lien Son , Lao Cai Prov., 23.VI.2015, T. Kompier leg. (TKC) ; 1♂, Lai Chau Prov., 28.V.2017, T. Kompier leg. (TKC) ; 3♂, Ch'Om, Tay Giang District, Quang Nam Prov., 18.IX.2016, V.Q. To leg. ( PQTC). [ China] 1♂ 1♀, Yangbijiang River , Yangbi County, Dali, Yunnan Prov., 12.VI.2013, H. Zhang leg. (KMP) ; 1♂, Xiangzhigou, Xinpuxiang Village, Guiyang City , Guizhou Prov., 28.VIII.2012, H. Zhang leg. (KMP). [ Laos] 3♂, N . Sekong, 5.VII.2011, T. Miyashita leg. ( KPM).

Other materials confirmed by field observations. [ Vietnam] Some individuals, Hoang Lien Son , Lao Cai Prov. , VII 2014, VI 2015, T. Kompier; Some individuals, Yen Bai Prov, . VI.2014, VI, VII, VIII, X 2015, VII 2016, T. Kompier; 6 exs, Cao Bang Prov., 18.VI.2015, T. Kompier; Some individuals, Bach Ma, Thua Thien-Hue Prov. , 5–8.VIII.2016, T. Kompier.

Notes. This species, preliminarily identified as Bayadera hyalina , is recorded from Vietnam and Laos for the first time. The identification of published or unpublished ‘ Bayadera hyalina ’ material collected outside the type locality of hyalina (Khasia Hills, Meghalaya, India), such as those from Thailand, Laos, Vietnam and China (Yunnan and Guizhou), remains uncertain until the material can be directly compared with topotypical Indian material.

Selys (1879) described Bayadera hyalina based on a single incomplete male from ‘Khasia Hills, Assam’ (in the present Meghalaya State, India); this holotype lacks abdominal segments S7–10 including appendages. Later, Fraser (1928, 1934) redescribed males and females based on several specimens from its type locality and noted and illustrated that the cerci have large spines near the base, but lack tubercles. However, Lahiri (1987) reported “presence of a small but prominent median tubercle on inner surface of superior anal appendages” in the specimens from Shillong, close to the type locality. Confusingly the position of the interior spine in cerci differs considerably in the rather crude illustrations presented by Fraser and Lahiri. The materials from Vietnam, Laos and China (Guizhou) used in this study have these characteristics and we identified these materials all as Bayadera hyalina , although we could not examine the holotype or materials from the type locality.

A similar species, Bayadera strigata Davies & Yang, 1996 , was described from Dali, Yunnan, southern China. Although we could not examine the type specimens of this species, we examined a pair of specimens obtained from its type locality, Dali, Yunnan. The structure of anal appendages of these specimens considered to be Bayadera strigata resembles that of B. hyalina from Vietnam, Laos, and China (Guizhou) with cerci having robust spines near the base, and 1–2 small tubercles in addition.

Thoracic pattern of the supposed Bayadera hyalina (sensu lato; including B. strigata ) varies geographically. Male prothorax is entirely black in central Vietnam, Laos and China (Guizhou), excluding two tiny spots on the margin of the posterior lobe of Chinese specimens, but prothorax has two yellow spots on the median lobes in northern Vietnam ( Fig. 7a, f ) and is even more prominently marked in Yunnan ( China) ( Fig. 7g –h ). Laotian specimens lack humeral stripe on male synthorax. This stripe is reduced to two oval spots at anterior margin of male synthorax in Guizhou ( China), and well defined as humeral stripes in northern Vietnam and Yunnan ( China) ( Fig. 7a, f–h ). Cerci of Laotian and Chinese specimens have two small tubercles besides the basal large spine, but those of Vietnamese specimens have only one typical tubercle ( Fig. 7b–d ). Thoracic pattern of the female from Yunnan ( China) is well defined with robust stripes ( Fig. 7h ), but it less clearly defined with only narrow stripes in the female from Vietnam ( Fig. 7f ). Wings of all specimens are hyaline, excluding two males from Yen Bai Province and many males from Guizhou, China, that have distinct apical darkening from the apical end of pterostigma to the wing border as shown in Figure 7e .

Donnelly (1994) recorded four males of Bayadera ( cf. hyalina ) from Doi Inthanon, Chiang Mai, Thailand, with a brief note that "this species is not longicauda, […,] the appendages have the superior with the sharp ventral basal spine and curvature resembling Fraser’s figure". Later, Hämäläinen & Pinratana (1999) and Hämäläinen (2017) identified the Thai specimens as Bayadera hyalina .

Distribution. Vietnam (Lai Chau, Lao Cai, Yen Bai, Cao Bang, Quang Nam, Thua Thien-Hue and Lam Dong [Hämäläinen in litt.] Provinces), China (Yunnan and Guizhou Provinces), Laos (Sekong Province), Thailand (Chiang Mai and Loei Provinces) ( Hämäläinen 2017), India (Meghalaya and West Bengal States) ( Fraser 1934, Lahiri 1987).

Figures

FIGURE 5. Bayadera continentalis. [5a–d] ♂ and ♀, Dong Van and [5e–h] ♂, Pia Oac. (5a) male head and thorax; (5b) appendages, dorsal view; (5c) appendages, lateral view; (5d) female head and thorax; (5e) male head and thorax; (5f) appendages, dorsal view; (5g) appendages, lateral view; (5h) wings.

FIGURE 7. Bayadera hyalina. [7a–f] ♂ and ♀, Yen Bai and [7g–h] ♂ and ♀, Yunnan. (7a) male head and thorax; (7b) appendages, dorsal view, (7c) appendages, lateral view; (7d) appendages, ventral view; (7e) male wings; (7f) female head and thorax; (7g) male head and thorax; (7h) female head and thorax.