Anisogomphus yingsaki, Makbun, 2017

Makbun, Noppadon, 2017, Anisogomphus yingsaki (Odonata: Gomphidae) sp. nov., a new gomphid species from Thailand, Zootaxa 4306 (3), pp. 437-443 : 438-442

Anisogomphus yingsaki sp. nov.

( Figs. 1–16 )

Holotype: ♂, Thailand, Sakon Nakhon province, Ban Muang, Ban Na Kha , altitude 170–175 m, 22-vi-2016, N. Makbun leg.

Paratypes (from the same location as in holotype): 1♀, 22-vi-2016; 2♂♂, 23-vi-2016, N. Makbun leg. The holotype and one female paratype are deposited in the Thailand Natural History Museum ( THNHM), Pathum Thani, Thailand. The other specimens are retained in the author’s private collection.

Etymology. The species name, a noun in the genitive case, honours Mr. Yingsak Paweenpermsuk, a dragonfly enthusiast who happened to find this species, took their photographs and sent them to the author for the identification. After scrutinizing his photos closely, the author realised that it was new species. Apart from that, he kindly took the author and his colleague to the type locality for specimen collection.

Description of holotype ( Figs. 1 , 3–12 )

Head. Eyes green in life and becoming brown after preservation; face black with whitish yellow pattern ( Fig. 3 ); occiput whitish yellow with black anterior margin, posterior margin slightly raised with a row of setae across the subapical area; vertex whitish yellow with black margin, slightly depressed in the middle; a pair of blunt tubercles behind lateral ocelli; antennae black; dorsal surface of frons entirely whitish yellow; anterior part of frons black with whitish yellow margin; postclypeus whitish yellow with two black markings, its margin black and concave centrally; anteclypeus and genae black; labrum whitish yellow with black margin, deep concavity in middle; mandible black with basal whitish yellow marking; labium, lateral and median lobe of labium pale.

Thorax. Prothorax black with whitish yellow anterior margin, slightly expanded in middle; median lobe black with a pair of elongate yellowish lateral spots, the anterior one larger than the posterior one; posterior lobe whitish yellow with black margin, depressed centrally; synthorax black with whitish yellow markings ( Figs. 4–5 ); antehumeral stripes almost straight, broader in the middle, slightly tapering at both blunt ends; humeral stripe reduced to small triangular spot under antealar sinus; mesothoracic collar whitish yellow; mesepimeron with yellow lateral stripe, expanded anteriorly at its apex, near its anterior margin, covered about a half of its width; metepisternum with yellow band, connected with metinfraepisternum stripe; metepimeron yellow with black margin, except some basal and apical areas; metinfraepisternum black with large yellow spot.

Legs black except coxae which are wholly pale, inner area of profemur pale, posterior of profemur with pale spot and metafemur with basal 2/3 pale; metafemur with two rows of small spines at base, and large widely spaced ones at distal half, the distal end of which reaches as far as the middle of S1 ( Fig. 5 ).

Wings. Hyaline, basally tinted with brownish ( Fig. 6 ); primary antenodals first and fifth. Ax 12 (left), 13 (right) on Fw, 9 both on Hw, Px 10 both on Fw, 9 (left), 10 (right) on Hw; anal triangle 3-celled; triangles not crossed; one crossvein in cubital space in both wings; two crossveins between Arc and R1–R4 junction in FW; pterostigma brown, braced, covered 3.5 cells below.

Abdomen. Black with pale markings ( Fig. 1 ) as follows: S1 with dorsal and lateral spots; S2 dorsally with triangular spot and laterally with square spot covering auricle; S3 with basal pale yellow ring and small lateral spot; S4–6 with basal ring and middorsal stripe; S7 gradually swollen apically from the middle with basal ring connected to dumbbell -shaped lateral spot ( Fig. 10 ); S8 with two pale small lateral spots; S9 apically with small middorsal spot; postero-dorsal edge of S8–9 slightly projected when viewed laterally; S10 entirely black.

Anal appendages. Length of cerci the same as S10 but longer than epiproct; in lateral view cerci whitish yellow, acutely cone-shaped, slightly curved, tip paler, sharp, and slightly bent upward, its ventral margin at slightly posterior of the middle with a small tooth pointing downward. Cerci slightly convergent in dorsal view; epiproct internally whitish yellow with darker outer margin and apex, diverging and bent inward apically ( Figs. 11– 12 ).

Accessory genitalia. Anterior lamina pale semicircular shape covered with long hairs; posterior hamulus pale with slightly narrower obtuse apex, anterior side apically concave with small subapically tooth ( Fig. 7 ).

Vesica spermalis. Vesicle triangular in shape; second segment elongate tubular and inflated distally; median segment expanded forming an elliptic shape; distal segment triangular shaped with apical part modified to a short flagellum ( Figs. 8–9 ).

Measurements (mm): Hw 27, abdomen (including anal appendages) 38, total length (with head and appendages) 53.

Variation in paratype males. One of the two paratype males is smaller and the other same size as the holotype, Hw 27–28, abdomen (including anal appendages) 35.5–38, total length (with head and appendages) 49.5–53. Ax 12–13 on Fw, 9–10 on Hw, Px 8–10 on Fw, 8–9 on Hw. S7 marking of one of the paratypes variable, the posterior spot of dumbbell-shaped lateral spot not connected to the rest. Two male paratypes possess a blunt flagellum. This is likely to be a result from penile organ extraction procedure.

Paratype female ( Figs. 2 , 13–16 ). Similar to male, slightly stouter and shorter, black with yellow pattern, but differs as follows; occiput black; postclypeus pale bordered with black and broken in the middle; wing slightly tinted with yellow; antenodals 13 on Fw, 8 (right), 9 (left) on Hw; postnodals 9 (right), 10 (left) on Fw, 9 (right), 10 (left) on Hw; abdomen almost evenly cylindrical, without obvious expansion in distal segments; S3 with lateral spot and small middorsal spot; S4–5 with smaller lateral spots and without middorsal spot; S6 with basal ring and the smallest lateral spot; S8 with lateral spot near posterior margin; cerci pale, about the same length as S10, with gradually tapering, pointed tip ( Figs. 14–15 ); valvula vulvae simple and reaching beyond S9 ( Fig. 16 ).

Measurements (mm): Hw 29, abdomen (including caudal appendages) 35.5, total length (with head and appendages) 50.5.

Differential diagnosis. The genus Anisogomphus presently comprises of 16 species, of which two species, A. orites Laidlaw, 1922 and A. vulvalis Yousuf & Yunus, 1977 , are known only from female specimens and a third one, A. ceylonicus (Hagen in Selys, 1878) , is known from a crushed immature male, a female, and exuvia (Bedjanič & van der Poorten 2013). Members of this genus can be divided into two groups by the shape of male anal appendages ( Karube & Kompier 2016). The first group has simple rod-like cerci and the other has more complex cerci, which are joined or almost joined to each other. Anisogomphus yingsaki sp. nov. is in the first group, which includes species such as A. bivittatus (Selys, 1854) , A. ceylonicus , A. flavifacies Klots, 1947 , A. forresti ( Morton, 1928) , A. maacki (Selys, 1872) , and A. resortus Yang & Davies, 1993 .

Anisogomphus yingsaki sp. nov. is most similar to A. bivittatus from India and Nepal, A. flavifacies and A. resortus from China, with which it shares similar shape of anal appendages. However, it can be distinguished from them by a combination of the following characters: antehumeral stripes on mesepisternum almost straight and broader in the middle, S7 with basal ring connected to dumbbell -shaped lateral spot, vesica spermalis with apical part modified to a short flagellum, and female valvula vulvae simple and reaching beyond S9.

It should be noted that a short flagellum of vesica spermalis of A. yingsaki sp. nov. is unique amongst the members whose vesica spermalis were illustrated ( A. flavifacies , A. resortus , A. maacki , A. nitidus Yang & Davies, 1993 , A. tamdaoensis ( Karube, 2001) , A. neptunus Karube & Kompier, 2016 , A. yanagisawai , and A. anderi Lieftinck, 1948 ). Distal part of vesica spermalis of those members possess a blunt end but A. yingsaki sp. nov. is the first member in the genus that has a short flagellum, a condition not previously reported in this genus.

Notes on habitat and behaviour. While many Anisogomphus species are found near montane streams (e.g. Fraser 1934), A. yingsaki sp. nov. was found perching on grass near large river with a sandy bottom. These dragonflies often perched on leaf surfaces, 20–30 centimetres above the ground, on sunny days and disappeared when it was clouded. They would perch nearby or higher when threatened. Other interesting species found in this area include Macrogomphus matsukii Asahina, 1986 , Epophthalmia frontalis Selys, 1871 , and Nychogomphus sp.

Anisogomphus yingsaki sp. nov. adults were also found patrolling along the river as dusk fell (from 17.00 to 19.00) on June 21–23, 2016. My colleague and I observed both males and females (but mostly males) patrolling over the water surface and hovering for few minutes before patrolling again. After doing this for some time, some of them perched on nearby bushes. We also once witnessed a hovering male grasping a female and flying into the forest near the river. This crepuscular activity was observed also in M. matsukii in this area.

Distribution. Besides its type locality in Sakon Nakhon in the northeast Thailand, A. yingsaki sp. nov. has been recently photographed in Chiang Rai (A.J. Pierce, pers. comm.) and in Prachin Buri (J. Sim, pers. comm.) in the North and South-east, respectively. According to Mr. Yingsak Paweenpermsuk, the flight period is from May to August.

Figures

FIGURE 1 – 2. Anisogomphus yingsaki sp. nov., photographed in nature by Noppadon Makbun, 22 - vi- 2016, Ban Na Kha, Ban Muang, Sakon Nakhon province: (1) male; (2) female.

FIGURE 3 – 12. Anisogomphus yingsaki sp. nov., holotype male: (3) head in frontal view; (4) synthorax in dorsal view; (5) synthorax in lateral view; (6) left fore- and hindwing; (7) accessory genitalia in lateral view; (8) accessory genitalia in ventral view; (9) vesica spermalis in lateral view; (10) marking on S 7; (11) anal appendages in lateral view; (12) anal appendages in dorsal view.

FIGURE 13 – 16. Anisogomphus yingsaki sp. nov., paratype female: (13) head in frontal view; (14) anal appendages in lateral view; (15) anal appendages in ventral view; (16) valvula vulvae in ventral view.