The genus Planaeschna McLachlan, 1895 and its subgroupings in Vietnam, with descriptions of three new species (Odonata: Aeshnidae) Author Kompier, Tom Schoutenstraat 69, 2596 SK Den Haag, the Netherlands. Author Karube, Haruki Kanagawa Prefectural Museum of Natural History, Odawara, Japan. Author Futahashi, Ryo National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki, Japan. Author Phan, Quoc Toan 0000-0002-3154-6546 The Center for Entomology & Parasitology Research, College of Medicine & Pharmacy, Duy Tan University, 550000, Da Nang, Vietnam. pqtoan 84 @ gmail. com; https: // orcid. org / 0000 - 0002 - 3154 - 6546 pqtoan84@gmail.com text Zootaxa 2021 2021-08-30 5027 1 1 35 journal article 10.11646/zootaxa.5027.1.1 1175-5326 5448029 CCF10500-01A3-476C-A4BE-57161E164EBD 2. Planaeschna tomokunii Asahina, 1996 ( Fig. 4 ) Planaeschna tomokunii : Asahina (1996) pp. 70–72, Figs 4–6 (description of female holotype ); Sasamoto et al. (2013) pp. 590–593, Figs 11 –22 (first description of male, photos of female holotype ). Materials examined. 1 ♀ , Tam Dao NP , Vinh Phuc Prov. , Vietnam , 24-IX-2015 , TK leg.; 1 ♂ , same locality and collector, 4-VI-2016 ; 1 ♂ , same location and collector, 3-VII-2016 ; 2 ♂♂ , same location and collector, 16-VII- 2016 ; 1 ♂ 1 ♀ , same location and collector, 17-VII-2016 ; 1 ♂ , same location and collector, 27-VIII-2016 . Notes. Asahina (1996) described P. tomokunii based on a single female. Without detailed explanation, he considered P. tomokunii to be closely related to P. taiwana . The description of Planaeschna species based on a single female is problematic, because there is little interspecific structural variation in females. For the identification of Planaeschna , the combination of the morphology of the male anal appendages and the maculation pattern is effective, but in 1996 there were no Planaeschna known from Vietnam . Planaeschna tamdaoensis with a black and yellow face and plain-faced P. tomokunii were the first two species described. Planaeschna tomokunii remained enigmatic until Sasamoto et al. (2013) described the male based on specimens collected at the type locality, allowing the species to be correctly identified. So far, P. tomokunii may be a true endemic of the Tam Dao mountain range. Of all Planaeschna species known from Vietnam or China , none have the combination of slender cerci and dorsal pattern of S2 of male P. tomokunii . The dorsal and lateral pattern of S2 is somewhat like that of P. crux , but that species has clearly paddle-shaped cerci (see Fig. 11A–E ). The anal appendages of P. tomokunii are similar to those of P. samurai and P. viridis (compare Fig. 4F–G with Figs 3G–H and 6B–C ), but differ in detail. The cerci are more parallel-sided in dorsal view compared to P. samurai , with a slightly longer epiproct, and in lateral view not waved and curving downward as in P. viridis , but gently curving upwards. The dorsal and lateral pattern of S2 distinguishes it clearly from both P. samurai and P. viridis (compare Fig. 4D–E with Figs 3E–F and 6D ). Furthermore, the triangular spot on the metepisternum is confluent with the lateral stripe on the mesepimeron in P. samurai and P. viridis , but separated in P. tomokunii (compare Fig. 4A–C with Figs 3B, D and 6A ). Ecology. Planaeschna tomokunii is found around 1000 m asl. on the densely forested slopes of Tam Dao, where it apparently breeds in small brooks and seeps. Field observations were done of specimens hawking at dusk over a car track through the forest on the mountainside. In one instance, a male successfully grabbed a female over the track. It occurred together with P. tamdaoensis . Distribution. Endemic to Vietnam ( Vinh Phuc Prov. )