Euthygomphus yunnanensis Zhou &amp; Wu 1992
Creators: name: Kosterin, Oleg E.
Publisher: name: Zenodo
Year: 2016
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Odonata
Gomphidae
Euthygomphus
Euthygomphus yunnanensis

description: <i>Euthygomphus yunnanensis</i> (Zhou &amp; Wu, 1992) Fig. 4–6, 7 a–b Previous reports from Cambodia: <i>Burmagomphus</i> sp. (part)— Kosterin 2010: 36, 55: 2 teneral &amp;female; photographed (misidentified), Koh Kong Province, Thma Bang River upstream waterfall, 5 km SW Thma Bang village, 15 iv 2010) <i>Merogomphus parvus</i> (Krüger, 1899) —Kosterin 2012: 34, 49, 78, figs 24, 49: still erroneous reidentification of the above photographic record; 1&amp;female;, Koh Kong Province, 6.5 km SW Thma Bang village, 23 viii 2011). <i>Merogomphus parvus</i> (Krüger, 1899) —Kosterin et al. 2012: 162 (listed). <i>Merogomphus parvus</i> (Krüger, 1899) — Kosterin 2015: 28 –29, fig. 21b, table 4: 1 teneral &amp;male;, Pursat Province, O’Som village, 24 iii 2015). <b>Specimens studied.</b> 1&amp;female; (dry, in envelope), Cambodia, Koh Kong Province, ‘ Microgomphus River’ 6.5 km SW Thma Bang village, 11°38'42–47'' N, 103°23'43–51'' E, 343–346 m a.s.l., 23 viii 2011; 1&amp;male; (collected teneral, hardened in captivity overnight, dry in envelope), the same locality, 2 vi 2014; 1&amp;female; (teneral, almost uncoloured, preserved in alcohol), Cambodia, Koh Kong Province, Thma Bang River 5 km SW Thma Bang village, 11°39'31'' N, 103°24'14'' E, 366 m a.s.l., 15 iv 2010; 1&amp;male; (collected teneral, hardened in captivity overnight, preserved in alcohol), Cambodia, Pursat Province, a river at O’Som village, 12°04'40–45'' N 103°12' 21–35'', 524–531 m a.s.l., 24 iii 2015; 1&amp;male; 1&amp;female;, Cambodia, Mondulkiri Province, downstream of Buu Sraa Waterfall, ‘ Loringae brook’ upstream its waterfall, 12°33'58''–34'19'' N 107°24'43'' –25'02'' E, 432–515 m a.s.l., 10 vi 2014 (dry in envelopes); 1&amp;female;, Cambodia, Mondulkiri Province, just downstream of Buu Sraa Waterfall, the main river right bank, 12°34'09'' N 107°25'07'' E, 456 m a.s.l., 4 viii 2016 (acetoned, dry in envelope); 1&amp;male;, Cambodia, Stung Treng Province, Thala Barivat District, a brook in open low deciduous dipterocarp forest, 13°48'02'' N 105°51'50'' E, 84 m a.s.l., 27 vii 2016 (acetoned, dry in envelope); 1&amp;female;, Cambodia, Stung Treng Province, Thala Barivat District and Commune, 0.5 km E of Srae Ruessei village, a brook similar to the above, 13°36'04''' N 105°55' 50' E, 67 m a.s.l., 28 vii 2016 (acetoned, dry in envelope); all collected by O. Kosterin, in the author’s collection. <b>Remarks.</b> The main diagnostic feature of this species is the penis (vesica spermalis) structure. Its distal segment (V4) in lateral view looks narrow, with a small ventrobasal expansion (Fig. 4 a,c,h–i), as illustrated before (Asahina 1986, Zhang &amp; Wu 1991) (Fig. 3 e,m–n). Unfortunately, neither author illustrated the ventral view of the penis of this species. The actual structure of the distal segment (V4) is as follows. Its ventral (outer) surface is almost flat, only slightly lengthwise concave (more in proximal part) (Fig. 4 f–g,k); its dorsal (inner) surface has two semicircular keels in its basal part (Fig. 4 j). In ventral view its shape resembles a duck’s beak or a hippopotamus’s muzzle (Fig. 4 f–g, k) (while the whole penis looks like a duck’s head and neck, Fig. 4 h): it slightly expands at the base and strongly expands at the apex. The apical margin of the ventral surface is somewhat rounded, while that of the dorsal surface is almost rectangular, with the membranaceous distal ejaculation pores between them (Fig. 4 f–g, k). If preserved in alcohol, the two short membranaceous ventroapical processes on the medial segment (V3) are well seen (Fig. 4 g–k). No trace of cornua (claws). Other important characters are: - Simple male cerci, yellowish white with a brownish base (Fig. 5 k–m), very slightly arched in lateral view (Fig. 5 l), pointed to a small apical tooth directed back, below which the apex is rounded, with a black area of low irregular fine knobs (Fig. 5 m). (Note the cercus is blunt in the Sumatran male of <i>M. parvus</i>, see Lieftinck 1941 and Fig. 1 c). - Epiproct with the branches rather slender, arched down and slightly hooked apically in lateral view (Fig. 5 l), in ventral view outer sides of the branches convex (Fig. 5 m) and incision between the branches shallow, evenly roundish (Fig. 5 m). - Female vulvar scale triangular with blunt lobes and a narrowly pointed incision between them (Fig. 5 n). - Simple occiput with scarcely defined ridge, straight in males (Fig. 5 g); in females it varies from nearly straight in specimen from Koh Kong Province (Fig. 5 h) to having two slight waves in specimens from Mondulkiri and Stung Treng Provinces (Fig. 5 j); one of the Mondulkiri females has vestigial knobs and the other wellexpressed spines at its sides just near the eyes. The occiput coloration is variable, perhaps geographically. In the male (Fig. 5 e,g) and females (Fig. 5 f,i–j) from Mondulkiri Province (eastern Cambodia), most of the occiput is yellow. The male from Stung Treng Province (northern Cambodia) has the occiput black, while the female from there has a central yellow spot. The male from Pursat Province (southwestern Cambodia) has a small indistinct yellow spot in the occiput centre. In both male and female (Fig. 5 h) from Koh Kong Province (also southwestern Cambodia), the occiput is brownish black. The same variable coloration of the female occiput and presence of the knobs/spines is reported for Thai and Vietnamese specimens by Asahina (1986) as well (Fig. 3 r–t): of the two Thai females illustrated by him, one had the occiput almost entirely yellow and without knobs (Fig. 3 p,r), and in the other the yellowish colour was nearly disappearing and there were vestigial knobs (Fig. 3 q,s); in the female from South Vietnam the knobs looked like minute spines (Fig. 3 t). - On metepisternum (Fig. 5 c–d), dorsal stripes broadly confluent to collar stripes in a hockey-stick-like manner. Collar stripes narrowly interrupted at the middle. - Antealar spot present invariably. The antehumeral stripes (well expressed in the holotype, see Fig. 3 d) are absent in mature Cambodian specimens (Fig. 5 a–d, 6a), even in two males collected teneral and kept overnight. However, one of those specimens, the male from Pursat Province, had the antehumeral stripes in its teneral condition (Fig. 6 c); the teneral females from the Thma Bang River also had these stripes (Fig. 6 d). Among the five Thai specimens reported by Asahina (1986) the Mae Hong Son female had an interrupted antehumeral streak, others not (Fig. 3 k). Apparently, the antehumeral stripes are present in teneral specimens and disappear with acquisition of the full colouring. Most probably, the holotype (Liu 1991) was collected teneral, or perhaps the stripes may be retained in maturity in the northern part of the range (Yunnan). Interestingly, in about half of the hindwings available (7 of 15, right one missing in one of the Mondulkiri), the 2nd primary antenodal is 6th (Fig. 7 a–b); otherwise it is 5th (in both wings of both Stung Treng specimens, the left hindwing of one of the females from Mondulkiri and in the left hindwing of the Koh Kong Province female), and in one case 7th (the left hindwing of the Pursat Province male). On the forewing the 2nd principal antenodal is 5th (Fig. 7 a–b), with two exceptions: in the Pursat Province male it is 6th on the left forewing and in one of the Mondulkiri females it is 4th on the left forewing. An incomplete basal antenodal is present in the forewing (Fig. 5 a–b, 7b), with exception of the Stung Treng female and one of the Mondulkiri females, in which it is absent on both wings. Other characters are mostly shared with other species of the genus <i>Euthygomphus</i>. Measurements (mm): males: forewing 25–26, hindwing 24–25, abdomen without appendages 28–31, total length (with appendages) 39–44, hind femur 7.0–7.3, fore pterostigma 2.5–2.7, hind pterostigma 2.9–3.0: females: forewing 25–26, hindwing 24–25, abdomen without appendages 28–31, total length (with appendages) 39–44, hind femur 7.0–7.4, fore pterostigma 3.2–3.3, hind pterostigma 3.4–3.5. Antenodals: 13–16 on forewing, 9–11 on hindwing; postnodals: 9–11 on both wings.
description: Published as part of <i>Kosterin, Oleg E., 2016, Reconsideration of the genera Merogomphus Martin, 1904, and Anisogomphus Selys, 1857, including erection of a new genus, with a new species and discussion of additional specimens from Cambodia, pp. 51-76 in Zootaxa 4171 (1)</i> on pages 62-68, DOI: 10.11646/zootaxa.4171.1.2, http://zenodo.org/record/261686
description: {"references": ["Zhou, W. - B. &amp; Wu, H. (1992) New species and record of Gomphidae from China. Journal of the Zhejiang Forestry College, 9 (4), 392 - 401.", "Kosterin, O. E. (2010) A glance at the Odonata of the Cambodian coastal regions: end of dry season in 2010. International Dragonfly Fund Report, 29, 1 - 75.", "Kruger, L. (1899) Die Odonaten von Sumatra. II Theil. Familie Aeschniden. Stettiner Entomologische Zeitung, 59 (7 - 9), 267 - 331.", "Kosterin O. E. (2015) Dry season Odonata of the Cardamonean coast (Cambodia and Thailand) revisited. International Dragonfly Fund Report, 89, 1 - 36.", "Asahina, S. (1986) A list of the Odonata from Thailand. Part XIII. Gomphidae- 1. Cho Cho, 9 (2), 29 - 43.", "Lieftinck, M. A. (1941) Studies on Oriental Gomphidae (Odon.), with description of new or interesting larvae. Treubia, 18 (2), 233 - 253.", "Liu, Z. (1991) Description of two new species of the genus Anisogomphus from China (Odonata, Gomphidae). Contributions of Shanghai Institute of Entomology, 10, 129 - 134."]}