Matrona taoi Phan & Hämäläinen, spec. nov.

(Figs. 1–7)

Material. Holotype 3: Vietnam, Phu Tho province, Tan Son district, Xuan Son National Park, Xom Coi, (21°06'56.6''N, 104°57'27.4''E), elevation 442 m, 15 xi 2010, Phan Quoc Toan leg. Holotype to be deposited in Vietnam National Museum of Nature (VNMN), Hanoi.

Paratypes: 1 3, 3 Ƥ, same locality as for holotype, 07 xii 2009, Phan Quoc Toan leg.; 2 3, 4 Ƥ, same locality as for holotype, 15 xi 2010, Phan Quoc Toan and Do Manh Cuong leg.). Paratypes are deposited in the authors’ collections; 2 3, 2 Ƥ in coll. Hämäläinen, the rest in coll. Phan.

Etymology. The species is named after Mr Nguyen Thien Tao (Biology Department, Vietnam National Museum of Nature) as a token of gratitude for his friendly support of the first author’s field work and research activity.

Diagnosis. A Matrona species with reddish-brown wings, lacking any milky coloured reticulation at the wing bases of the male; apical 1/3rd of male fore wing subhyaline. Posclypeus metallic green. Ventral side of the apical segments of abdomen a conspicuous pale olive yellow.

Description of male (Figs 1, 3). Head: Labium olive yellow, the lateral lobes black at tips. Labrum black with an olive yellow median band, narrowed in the middle; in older specimens the yellow colour reduced to two separate spots. Base of mandibles largely yellow. Anteclypeus black with an obscure yellow spot in the middle. Postclypeus shining metallic green. Frons and upper surface of head black with obscure metallic green sheen. Genae black. Antennae dark, with a yellowish stripe on pedicel. Prothorax dark metallic green. Synthorax dark metallic green. Pale yellow portions are restricted to the level anterior to stigma and around metepimeron (Fig. 3). Underside of synthorax largely pale yellow. Legs: Coxae pale yellow with black markings on pro- and mesothoracic legs. Femora black with flexor surface partly pale in younger specimens, more markedly so in meso- and metathoracic legs. Tibiae black; meso- and metathoracic tibiae moderately curved (Fig. 3). Wings (Fig. 5) largely brownish, the apical 1/3rd of fore wing subhyaline; in hind wing the apical part slightly more hyaline than base; this difference less marked than in fore wing. In hind wing lower half darker in middle section of wing. Venation dark violet red. Reticulation sparse for genus, best seen in number of intercalary veins and density of crossveins in the area defined by CuP and wing border (Fig. 7) and in wing tip. Only 1–3, partly reticulated, crossveins in median space. Cubital space with 17–20 crossveins in fore wing, 17–20 in hind wing (in holotype 20 crossveins in all wings). Quadrangle with 13–18 crossveins in fore wing, 14–20 in hind wing (in holotype 15–13 and 18–18, respectively). Antenodals (in first row) number 41–53 in fore wing and 36–48 in hind wing (in holotype 41–41 and 38–36, respectively). Arculus (Arc) situated at the level of the fifth antenodal. Pterostigma absent in both wings. Abdomen metallic bluish-green dorsally and laterally; the lower half of side of S10 yellow (Fig. 3). Ventral side of S1-S5 blackish brown, S6-7 obscurely pale yellow and S8-S10 conspicuous pale olive yellow (Figs 1, 3). Anal appendages of the typical shape for the genus: cercus wholly black, bearing a row of small spines laterally; paraproct more than half of the length of cercus, black at tip, yellow laterally and ventrally.

Measurements (mm): Hind wing 38–42 (in holotype 38); abdomen (incl. appendages) 54–61 (in holotype 54).

Description of female (Figs 2, 4): Head and thorax coloured as in male. Wings (Fig. 6) reddish-brown throughout, an obscure darker band in the apical third of hind wing, the darker colour extending basad along wing border. Venation reddish brown to pale brown. Reticulation as sparse as in male. Median space of fore wing with 1–3 crossveins; 2–4 crossveins in hind wing. Cubital space with 18–23 crossveins in fore wing, 18–23 in hind wing. Quadrangle with 12–20 crossveins in fore wing, 15–19 in hind wing. Antenodals (in the first row) number 45–54 in fore wing and 41–48 in hind wing. Pseudopterostigma yellowish cream, short, covering 6–9 underlying cells. Abdomen dark reddish brown, the apical segments obscurely pale laterally.

Measurements (mm): Hind wing 44–46; abdomen (incl. appendages) 53–57 mm.

Biology. The species was found on three streams located about 4–5 km from the Centre of Xuan Son Community. Two of the streams were open in places, 3–5 m and 5–10 m wide, respectively. Matrona taoi were collected along sections of these streams where riffles and quieter waters alternate and where the banks are densely vegetated. The third stream, a 1–7 m wide shaded branch of the narrower stream above, is in primary forest. Other calopterygids occurring on these streams were Matrona basilaris Selys, Neurobasis chinensis (Linnaeus), Ve s t al is gracilis (Rambur), Vestalaria miao (Wilson and Reels) and Noguchiphaea yoshikoae Asahina. For more details and photographs of these streams, and of their calopterygid, chlorocyphid and euphaeid fauna, see Phan & al. (2011).

Females were observed from 0800 h to 1700 h, but males were seen only around noon. The damselflies perched on tree branches and bushes at the water’s edge, 50 cm to 2–3 m above the surface. No territorial behaviour was documented. In sunshine the wings display a distinct reddish violet sparkle.