Chlorogomphus (Orogomphus) danhkyi, Phan & Karube & Hung & Anh, 2021

Phan, Quoc Toan, Karube, Haruki, Hung, Nguyen Viet & Anh, Tran Dinh, 2021, Description of Chlorogomphus danhkyi sp. nov. from Vu Quang National Park, central Vietnam with notes on other congeners from the Park (Odonata Chlorogomphidae), Zootaxa 4985 (1), pp. 102-110 : 103-106

Chlorogomphus (Orogomphus) danhkyi sp. nov.

( Figures 1–15, 18, 19 )

Holotype: ♂, Khe Ro (15.0444 N, 107.9270 E, altitude 1480 m), Vu Quang National Park, Kim Quang Commune , Vu Quang District , Ha Tinh Province, 2.vi.2020, Q. T. Phan leg.

Paratypes: 6 ♂♂, 2 ♀♀ (a female specimen with both pairs of wings tip is broken), same data as the holotype.

Type deposition. Specimens have been deposited in the Zoological Collection of Duy Tan University , Da Nang City, Vietnam apart from two paratype males, which will be deposited in the Kanagawa Prefectural Museum of Natural History , Japan.

Etymology. Danhkyi, a noun in genitive case, derived from the name of the director of Vu Quang National Park, Mr. Nguyen Danh Ky, to honor his strong support for the authors field surveys in the national park.

Description of holotype. Head ( Figs 1, 2 , 18 ). Labium yellow with dense hairs apically; labrum and genae entirely black; anteclypeus dark yellow with two black spots laterally; yellow postclypeus with two black dots. Frons black, its anterior margin in dorsal view bisinuate, its medial margin produced anteriorly ( Figs 2, 3 ). Antefrons entirely black laterally with a large rugose circular depression ( Fig. 1 ). Postfrons black with a bisinuous yellowish area anteriorly ( Fig. 2 ). Antennae black, anterior part of the first and second segments yellow; raised vertex black, cordate ( Fig. 18 ); occiput black with long setae posteriorly.

Thorax ( Fig. 3 ). Prothorax entirely black. Synthorax black with yellow as follows: mesepisternum with a thin stripe above larger, slightly curved antehumeral stripe; metepisternum with a well-defined stripe covering spiracle; lower margin of metepimeron yellow. Mes- and metinfraepisternum with yellowish markings. Coxae partially yellow, legs black.

Wings ( Fig. 12 ) membrane amber, venation black. Ax/Px: 26/ 12 in left Fw; 23/ 14 in right Fw; 22/ 15 in left Hw; 20/ 14 in right Hw. Median space with 2 crossveins in Fw and 3 crossveins in Hw. Basal triangle in hind wing 3- celled. Triangle 2-celled and cubital space with 7 crossveins in all wings. Anal loop 12–13-celled. Pt black, 4.0 mm in length, covering 3.0–3.5 underlying cells.

Abdomen ( Fig. 12 ). S1–2 black with an oblique yellow extending posterodorsally from ventral half of S1 to latter half of S2; S2–3 with a ventral yellow line; S3–6 black with a small subapical dorsal spot; S7 slightly expanded, black with a large subapical yellow annulus; S8–10 entirely black.

Secondary genitalia ( Fig. 4 ) short and robust; anterior lamina slightly curved apically, narrower towards apex. Posterior hamule shorter than anterior lamina, tip curved anteriorly.

Vesica spermalis ( Figs 5, 6 ) typical the genus with two long projections at posterior corners of glans and the second segment broader, with stout spines.

Anal appendages ( Figs 14, 15 ) entirely black. Cerci subequal in length to S10 and shorter than epiproct. In dorsal view, cerci broadly arcuate medially, broad basally gradually narrowing apically, terminating in a posterodistally directed tip; in lateral view, cercus broad basally, with a small lateral tooth on outer margin just beyond distal half then narrowing apically with an enlarged tridentate process at terminal fifth, the middle tooth the longest an directed posteroventrally, the smaller subapical tooth directed ventrally; epiproct in dorsal view broad, deeply incised, widely divided medially, cleft V-shaped, tip of each lateral branch armed with a more or less dorsally curved tooth; in lateral view epiproct slender, broadening apically, ventroapical margin rounded, dorsoapically armed with dorsal tooth.

Measurement (in mm). Hindwing 46, abdomen (including appendages) 62.

Description of paratype female. Head. Frons smaller ( Fig. 7 ), not protruding in dorsal view ( Fig. 8 ) as in holotype ( Figs 1–2 ); yellow marking on postfrons linear and much narrower ( Fig. 7 ); vertex larger, oblong ( Fig. 19 ) and distance between eyes 1.5 mm.

Thorax similar to holotype but antehumeral and metepisternal stripes much wider; posterior margin of metepimeron with a small yellow spot ( Fig. 9 ).

Wings ( Fig. 13 ) hyaline, slightly amber or smokey. Ax/Px: 26/ 17 in left Fw; 25/ 17 in right Fw; 24/ 21 in left Hw; 24/ 20 in right Hw. Median space with 2 crossveins, triangles 3-celled, cubital space with 7 crossveins in all wings. Anal loop with 16-cells. Pt black, 4 mm in Fw, 5 mm in Hw, each covering 4 underlying cells.

Abdomen ( Figs 9 , 13 ). S1 black and largely yellow laterally; S2 almost entirely yellow, anterior dorsal part of S2; S3–7 black each with a small subapical dorsal spot; ventral margin of S3 yellow; S8–10 entirely black.

Cerci entirely black, as long as S10 and vulvar lamina as in Figs 10–11 . Ventral keels of S9 pyramid shaped ( Fig. 11 ).

Measurement (in mm). Hindwing 54, abdomen (including appendages) 63.

Variation in paratype males. Paratype males show little variation from the holotype except by measurement data: Hw 44–46 mm; abdomen (including appendages) 60–65 mm; and wing venation statistics (Ax/Px: 24–28/ 11– 12 in Fw, 20–22/ 14–15 in Hw; Anal loop 10–13-celled).

Variation in paratype female. Another paratype female differs from the described female as follow: Ax/Px 25–26/ 14 in Fw, 19–20/ 17–18 in Hw. Anal loop of Hws with 13–14 cells.

Differential Diagnosis. Chlorogomphus danhkyi belongs to the subgenus Orogomphus Selys, 1878 , together with other five other species: C. dyak (Laidlaw, 1911) and C. manau Dow & Ngiam, 2011 from Borneo; C. piaoacensis Karube, 2013 from North Vietnam; C. splendidus (Selys, 1878) from Philippines and C. yoshihiroi Karube, 1994 from West Malaysia ( Karube 1995, 2013). Within this subgenus, C. danhkyi and C. piaoacensis form a subgroup differing by short cercus with apex expanded bearing an incurved ventral projection in apical half ( Figs 14, 15 ). The male of C. danhkyi differs from its closest congener, C. piaoacensis by: (1) cerci with a short spine on the outer outline the cercus ( Fig. 14 ) (absent in C. piaoacensis — Fig. 16 ); and (2) tip of each lateral branch of epiproct in dorsal view acute ( Fig. 15 ) (blunt in C. piaoacensis — Fig. 17 ). Female of C. danhkyi differs from C. piaoacensis by shape of the raised vertex ( Fig. 19 ) and ventral keel of S9 pyramid ( Fig. 13 ) (vertex hemispherical and valvula trapezoid C. piaoacensis, Karube 2013 : Fig. 10b 2, 10k ).

The cercus of C. danhkyi is similar to C. (Sinorogomphus) vietnamensis Asahina, 1969 , but is comparatively shorter and the posteroventrally curved tooth shorter, about twice as long as the subapaical ventral tooth in lateral view ( Fig. 14 ) whereas the medially arcuate cercus of C. vietnamensis is comparatively longer, subequal in length to epiproct, its posteroventrally curved distal tooth acute and is about 4x as long as subapaical tooth ( Karube 2013: Fig. 16g ). The tip of paraproct in lateral view in C. danhkyi is unidentate but is bidentate in C. vietnamensis .

Habitat and ecology. Chlorogomphus danhkyi was found within high humidity at high altitude along a clear stream (4–8 m width) with large rocks and dense vegetation ( Figs 26, 27 ) close to the border between Vietnam and Laos ( Fig. 28 ). Males were seen usually coursing up and down the stream at about 0.5– 1 m above the water’s surface while the females seldom appeared at slower parts of the stream in order to oviposit before quickly flying away. At the type locality, we also collected C. nasutus and C. tunti and other odonates including Caliphaea thailandica Asahina, 1976 , Rhinocypha watsoni van Tol & Rozendaal, 1995 , Cryptophaea vietnamensis (van Tol & Rozendaal, 1995) , Euphaea saola Phan & Hayashi, 2017 , Agriomorpha fusca May, 1933 , Calicnemia miles (Laidlaw, 1917) , Coeliccia pyriformis Laidlaw, 1932 , Coeliccia scutellum Laidlaw, 1932 , Protosticta caroli van Tol, 2008 , Planaeschna sp. , Amphigomphus nakamurai Karube, 2001 , Macromia calliope Ris, 1916 and Idionyx carinata Fraser, 1926 .

Figures

FIGURES 1–11. Features of Chlorogomphus danhkyi sp. nov., holotype ♂ & paratype ♀. (1) head & thorax ♂; (2) head & thorax ♀; (3, 4), head ♂, frontal and dorsal view; (5, 6), head ♀, frontal and dorsal view; (7), accessory genitalia; (8, 9), vesica spermalis in lateral and ventral view; (10, 11), abdominal tip ♀, lateral and ventral view.

FIGURES 12–13. Habitus of Chlorogomphus danhkyi sp. nov. (12), holotype ♂ & (13), paratype ♀. Measurements in centim- eters.

FIGURES 14–19. Appendages and head of Chlorogomphus spp., ♂. (14, 15), appendages of C. danhkyi sp. nov.; (16, 17), appendages of C. piaoacensis; (18, 19), head of C. danhkyi sp. nov., holotype ♂ & paratype ♀, dorsal view.

FIGURES 26–28. Habitats and distribution of Chlorogomphus spp. (26, 27), Khe Ro; (28), distribution of C. danhkyi sp. nov. (yellow circle) and C. piaoacensis (red circle).