Asiagomphus acco Asahina 1996
Creators: name: Kompier, Tom
Publisher: name: Zenodo
Year: 2018
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Odonata
Gomphidae
Asiagomphus
Asiagomphus acco

description: Asiagomphus acco Asahina, 1996
(Figs. 1, 2, 3a–b, 5h, 6h, 13a–b)
Asiagomphus xanthenatus acco: Asahina (1996), pp. 22–24, figs. 2–9 [type, northern Vietnam]; Wilson (2005), p. 132, fig. 15 [records from Guangxi, China and discussion of specific status].
Asiagomphus acco: Do et al. (2011), pp. 8–10, fig. 8; von Ellenrieder et al. (2015), p. 5 [species list]; Karube (2014), p. 69 [species list]; Yokoi & Souphanthong (2014), p. 84 [distribution map], p. 37 (Plt. 14).
Material examined: 1 ♂, Tay Thien, Tam Dao NP, Vinh Phuc Prov, northern Vietnam, 18-V-2014, TK leg.; 1 ♀, Yen Bai Prov., northern Vietnam, 20-VI-2015, TK leg.; 1 ♂, Quang Nam Prov., central Vietnam, 21-VI-2016, TK leg.
Additional records based on field observations by TK: 1 ♂, Ba Be NP, Bac Kan Prov., northern Vietnam, 21-VII-2013; 6 ind., Tay Thien, Tam Dao NP, Vinh Phuc Prov., northern Vietnam, 18-V-2014; 1 ♂, Ba Vi NP, Ha Noi, northern Vietnam, 25-V-2014; 3 ind., Xuan Son NP, Phu Tho Prov., northern Vietnam, 31-V-2014; 2 ind., Xuan Son NP, Phu Tho Prov., northern Vietnam, 1-VI-2014; 4 ind., Xuan Son NP, Phu Tho Prov., northern Vietnam, 8-VI-2014; 2 ind., Tam Dao NP, Vinh Phuc Prov., northern Vietnam, 15-VI-2014; 1 ind., Cao Bang Prov., northern Vietnam, 23-VI-2014; 1 ind., Bac Kan Prov., northern Vietnam, 25-VI-2014; 1 ind., Bac Kan Prov., northern Vietnam, 26-VI-2014; 2 ind., Xuan Son NP, Phu Tho Prov., northern Vietnam, 4-VII-2014; 2 ind., Cao Bang Prov., northern Vietnam, 8-VII-2014; 1 ind., Cao Bang Prov., northern Vietnam, 9-VII-2014; 5 ind., Xuan Son NP, Phu Tho Prov., northern Vietnam, 18-IV-2015; 2 ind., Lang Son Prov., northern Vietnam, 2-V-2015; 1 ind., Ha Tinh Prov., central Vietnam, 9-V-2015; 1 ♀, Cuc Phuong NP, Ninh Binh Prov., northern Vietnam, 22-V-2015; 7 ind., Xuan Son NP, Phu Tho Prov., northern Vietnam, 30-V-2015; 1 ind., Cuc Phuong NP, Ninh Binh Prov., northern Vietnam, 16-VI-2015; 2 ind., Cao Bang Prov., northern Vietnam, 28-VI-2015; 1 ♂, Xuan Son NP, Phu Tho Prov., northern Vietnam, 29-VI-2015; 1 ♂, Tam Dao NP, Vinh Phuc Prov., northern Vietnam, 19-VII-2015; 1 ♂, Xuan Son NP, Phu Tho Prov., northern Vietnam, 23-IV-2016; 1 ♂, Thua Thien - Hue Prov., central Vietnam, 3- V-2016; 1 ♂, Xuan Son NP, Phu Tho Prov., northern Vietnam, 29-V-2016; 6 ind., Quang Nam Prov., central Vietnam, 21-VI-2016; 1 ♂, Thua Thien - Hue Prov., central Vietnam, 21-VI-2016; 10 ind., Xuan Son NP, Phu Tho Prov., northern Vietnam, 21-V-2017; 3 ind., Xuan Son NP, Phu Tho Prov., northern Vietnam, 27-V-2017; 5 ind., Quang Binh Prov., central Vietnam, 5-VI-2017; 1 ♂, Cuc Phuong NP, Ninh Binh Prov., northern Vietnam, 11-VI- 2017; 4 ind., Bac Kan Prov., northern Vietnam, 9-VII-2017; 2 ind., Cao Bang Prov., northern Vietnam, 16-VII- 2017.
Discussion. Males of Asiagomphus acco are easily identified by their thorax pattern with a dorsal stripe and a single lateral stripe (over the mesepimeron), but without antehumeral stripe or second lateral stripe over the metepisternum, and with all yellow metepimeron. S1–2 are largely yellow, but S3–8 are black, with sometimes a small antero-dorsal spot on S7. S9 has a large yellow postero-dorsal spot. The pattern is very consistent (Figs. 1, 2a–c). The combination of largely black abdomen and black metepisternum is enough to identify the male, but in addition the sub-basal ventral tooth to the cerci in combination with the distinct slender branches of the epiproct in lateral view, which are very straight both dorsally and ventrally (Fig. 6h), can be used for in-hand identification. The female has the same thorax pattern as the male, but has largely yellow S1–2, with only a black dorso-lateral spot on S1 and some black centrally on the dorsum of S2 at the posterior margin. S3–6 all have paired posterior dorsal spots, somewhat increasing in size from S3 to S6. S7–8 and S10 are black, or rarely S8 with a small dorsal yellow spot, and S9 has a relatively small postero-dorsal spot. The female too is quite consistently patterned (Figs. 1, 2d–f).
Asahina (1996) originally described Asiagomphus acco as a subspecies of A. xanthenatus. However, this was a strange taxonomic solution, as that species has clearly different cerci without a ventral sub-basal tooth and different epiproct (compare Figs. 5h, 6h with Figs. 5e, 6e). It is also completely differently patterned (compare Figs. 1, 2, 13a–b with Fig. 10d) and has different hamuli (compare Figs. 3a–b with Figs. 3e–f). I strongly support the view by Do et al. (2011) that A. acco should be considered a separate species in its own right.
Habitat and ecology. Asiagomphus acco is a spring species, locally common, appearing in the second half of April and flying to the end of July. Sampling bias has been towards northern Vietnam, but the species was observed as far south as Quang Nam Province in central Vietnam. It inhabits clear, shallow streams, generally under deep forest cover, and is very approachable, unlike many other species in the genus.
description: Published as part of Kompier, Tom, 2018, The genus Asiagomphus in Vietnam, with descriptions of three new species, and first descriptions of the male of Asiagomphus auricolor (Fraser, 1926) and of the female of Asiagomphus reinhardti Kosterin & Yokoi, 2016 (Odonata: Gomphidae), pp. 301-330 in Zootaxa 4462 (3) on pages 302-303, DOI: 10.11646/zootaxa.4462.3.1, http://zenodo.org/record/1441611