Asiagomphus reinhardti Kosterin & Yokoi, 2016
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), Zootaxa 4462 (3), pp. 301-330 : 319-324
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|Asiagomphus reinhardti Kosterin & Yokoi, 2016|
Asiagomphus reinhardti: Kosterin & Yokoi (2016) pp. 35–42, figs. 1–4 [description of holotype male from Cambodia and paratype male from Laos]; Kosterin (2016), pp. 45–46, fig. 38 [photo of male, records from Vietnam].
Asiagomphus sp. 1: Yokoi & Souphanthong (2014), p. 15 [species list], p. 37 [scan of male], p. 57 fig. 62 (anal appendages in lateral view], p. 64 note 66 [specimen info], p. 84 [distribution map].
Material examined: 1 ♂ 1 ♀ [this female used for description], Bao Loc, Lam Dong Prov., (appr. 11.720 N, 107.730 E), central Vietnam, 17-V-2016, TK leg GoogleMaps ; 1 ♀, K’bang, Gia Lai Prov., (appr. 14.126 N, 108.629 E), central Vietnam, 19-VI-2016, TK leg. GoogleMaps ; 2 ♂♂ 1 ♀, same location and collector, 20-VI-2016 GoogleMaps ; 1 ♂, Bao Loc , Lam Dong Prov., 10-V-2017, TK leg.
Additional records based on field observations by TK: 2 ♂♂, Bao Loc , Lam Dong Prov., central Vietnam, 17-V-2016 ; 15 ind., K’bang, Gia Lai Prov., central Vietnam, 19-VI-2016 ; 7 ind., same details as previous, 20-VI- 2016; 5 ind., Bao Loc , Lam Dong Prov., central Vietnam, 12-V-2017 ; 4 ♂♂, K’bang, Gia Lai Prov., central Vietnam, 13-V-2017 .
Head. Lateral lobes of labium pale yellow, median lobe dark brown. Labrum black with two small pale yellow spots on either side of middle towards superior margin. Anteclypeus blackish brown. Postclypeus black. Base of mandibles yellow. Postfrons with broad yellow stripe, extending downward to cover the dorsal margin of the otherwise black antefrons. Posterior edge of postfrons black. Cranium black, lateral ocelli connected by a raised ridge, which does not continue posteriorly of ocelli. Lateral ocelli with slightly raised ridge along outer side, which has distinct single spike between ocelli and compound eye at distal end ( Fig. 9f View FIGURE 9 ). Spikes as high as widest width of ocelli. Occiput black, grooved lengthwise and slightly concave, occipital ridge with sparse and short black hairs and raised centrally into low triangular point. Antennae black, but top of first segment pale.
Thorax. Prothorax with anterior lobe yellow but black laterally, and median lobe with small yellow central paired spots and pair of square lateral spots, posterior lobe with small yellow central spot. Synthorax black with yellow markings as follows: Mesepisternum with dorsal stripe, straight, rather broad, merging with collar stripe to form two inverted “7” shapes. A small antehumeral spot and hint of antehumeral stripe towards ventral end of humeral suture. Black mesepimeron with straight broad lateral stripe. Metepisternum black with small yellow spot at postero-dorsal corner and another tiny and indistinct yellow mark in the middle near posterior margin. Metepimeron almost completely pale yellow, but black stripe over metapleural suture. Coxae and legs black.
Abdomen. Black with yellow markings as follows: S1 almost completely yellow, dorso-laterally black with black hairs; S2 yellow apart from blackish smudge at postero-ventral corner and black mark at postero-dorsal margin, covering about one-third of dorsum; S3 with triangular baso-lateral spot; S4–7 with short antero-dorsal half-ring, dorsally constricted on S4–6 and most prominent on S7; S8 with thin yellow line along dorso-lateral anterior margin, interrupted along dorsum; S9 with large yellow marking on posterior fourth dorsally; S10 with longitudinal yellow dorsal stripe over posterior half. S7–9 markedly widened.
Vulvar lamina. Somewhat longer than wide, deeply incised to about halfway, the posterior halves bend upward, apices bluntly triangular and somewhat divaricate.
Wings. Hyaline with black veins. Cubito-anal space with one crossvein, all triangles uncrossed, nodal index 14–17:16– 15 in FW, 13–11: 11–14 in HW. Pt brown, 4 mm, covering 5–5.5 cells in FW and 4.5–5 in HW.
Anal appendages. Cerci conical, sharply pointed apically, in lateral view straight, in dorsal view somewhat bent inward apically. Basally and laterally blackish, dorsally whitish but apex black. Epiproct pale yellow.
Measurements (in mm). Total length (incl. appendages) 58, HW 39.
Variation in females. One female from Gia Lai ( Fig. 12d View FIGURE 12 ) with lateral lobes of labium blackish brown, labrum all black. Spikes near compound eye seam reduced to small knob and protrusion of occipital ridge reduced to shallowly angular profile. Thorax with tiny antehumeral spot left, right antehumeral spot somewhat elongated, as indication of antehumeral line, metepisternum without central yellow spot, but right with small yellow mark behind spiracle. S1 with more black dorsally, black mark at postero-dorsal margin of S2 continuing anteriorly to form two black ‘fingers’ extending along yellow dorsal stripe almost to the anterior margin. Yellow longitudinal line over S10 starting at anterior margin and almost covering complete segment. Second Gia Lai female ( Fig. 12c View FIGURE 12 ) similarly with spikes reduced to tiny knob, but triangular spike on occipital ridge present. Labrum with more prominent pale yellow spots. Lateral marks on median lobe of prothorax more prominent. Thorax with narrow, but distinct, complete antehumeral stripe. Metepisternum with three separate large yellow markings on posterior half, one dorsally, one in the middle and one near spiracle. S2 without blackish mark ventrally and ‘fingers’ of dorsal posterior mark extending only to middle. S8 with a pair of yellow lateral spots towards posterior margin laterally. Yellow mark on S9 covering posterior third of segment and yellow longitudinal line over S10 covering complete segment. Cerci completely pale yellow and epiproct bright yellow. Wings in both specimens slightly smoky towards apices. Slight variation in venation. One specimen 14–17:17–13 / 14– 12:12–14, the other 15–18:18–13 / 12–12:11–13. Pt 4.5 mm in one specimen, covering 6 cells in HW.
Measurement (in mm): Total length (incl. appendages) 57–59, HW 37–38.
Differential diagnosis. Not all females of Asiagomphus species are known, but the female of A. reinhardti has several remarkable characteristics.2 Structurally the most prominent is the lack of the connection between the ridge that connects the lateral ocelli and the margin of the compound eyes. In most female Asiagomphus the ridge continues prominently behind the lateral ocelli and is often adorned with spikes. Other features that support the identification are the yellow lines along the anterior margin of S8 and the longitudinal mid-dorsal line over S10.
Variation in Vietnamese males. One male from Bao Loc with completely black labrum. The small swelling at the middle of the occiput is missing in three males and slight in one. None of the four Vietnamese males have either an antehumeral spot or antehumeral stripe, and three have completely black metepisternum, the fourth with a tiny yellow mark towards the postero-dorsal corner. In one male the postero-lateral spots on S8 are lacking and the yellow lines along the anterior margin minimal, in one male the postero-lateral spots are almost imperceptible ( Fig. 12a View FIGURE 12 ), and in the remaining two these spots are obvious. However, one male photographed, but not collected, has a prominent antehumeral stripe and an irregular line over the metepisternum ( Fig. 13e View FIGURE 13 ), and another has an antehumeral spot ( Fig. 13f View FIGURE 13 ).
Habitat and ecology. Near Bao Loc in Lam Dong Province, the species was found at a sandy-bottomed stream, at well over alt. 1,000 m in a partly opened primary forest area. The stream contained many rocks under forest cover, but was more sandy and shallow next to a cleared area, which was where males congregated and females were observed ovipositing. Near K’Bang in Gia Lai Province, the species was abundant at a small stream at approximately alt. 450 m with muddy and sandy bottom that ran through an area with larger cobbles and stones. The stream ran through a logged forested area and at this point crossed a track before continuing along a coffee plantation.
Discussion. Asiagomphus reinhardti was described by Kosterin & Yokoi (2016) based upon single males from Cambodia and Laos. The remarkable extension of the posterior margin of S10 and the shape of the anal appendages make this a unique species within the genus ( Kosterin & Yokoi 2016) and easy to identify.
It is remarkable that an Asiagomphus species with such distinctive features would have gone unnoticed in the Central Highland region of Vietnam until know, because for instance the Bao Loc area is relatively well-sampled. However, with its discovery by the author at two separate sites about 400 km distant from each other (reported in Kosterin 2016) this distinctive species is now known to occur over quite a large area covering the southeastern corner of Laos, eastern Cambodia and the Central Highlands from Vietnam.
The males from Cambodia and Laos differed in the extent of yellow patterning (for instance presence versus absence of the antehumeral stripes, or presence or absence of yellow spots on the metepisternum), with the Laotian male being generally darker than the Cambodian one. The Vietnamese material is even more diverse, including males that lack yellow spots on the labrum, lack antehumeral spots and have no yellow postero-lateral marks on S8, next to specimens with for instance complete antehumeral stripe.
The shape of the female occiput ( Fig. 9f View FIGURE 9 ) is also remarkable. This possibly unique feature may be connected to the remarkable shape of the male appendages and posterior margin of S10 to allow pairing.
The variation found in both the males and females of this species should serve as a warning when describing or identifying Asiagomphus specimens. The three female specimens already display quite a range in color patterns and structural characters (presence or absence of antehumeral stripe, extent of yellow on metepisternum, labrum with or without yellow marks, cerci varying from blackish in lateral view to completely pale yellow, presence or absence of prominent spikes on occiput and occipital ridge). Several species in the genus have been described based on single specimens that differed in some of these possibly variable characters. The presence or absence of longitudinal markings along the abdomen, or presence of half-rings, appears to be much more consistent. In many species, the thorax markings are also much more stable than in others.
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