Orthetrum aberrans, Yu, 2025

Yu, Xin, 2025, A new species Orthetrum aberrans sp. nov. (Odonata: Libellulidae) from China, Zootaxa 5642 (1), pp. 75-88 : 80-85

Orthetrum aberrans sp. nov. ( Figs. 4–7 )

Holotype: ♂, ID ccr0178 , China, Chongqing, Wushan County, (30.751 N, 109.883 E, 1800 m a.s. l.), 12 July 2023, Xin Yu leg. Paratypes: 1 ♂, ID ccr0181 , China, Chongqing, Wushan County, 12 July 2023, Xin Yu leg ; 1 ♂, ID ccr0179 , China, Chongqing, Nanchuan County, 3 July 2023, Xin Yu leg ; 1 ♂, ID ccr0193 , China, Shanxi, Lishan , 7 August 2022, Junhao Qiu leg. All type specimens deposited in the College of Life Sciences, Chongqing Normal University, Chongqing, China .

Etymology. The name emphasises the unusual appearance of the new species.

Description of holotype ( Figs. 4–5 ). Body brown with black and yellow markings.

Head. Eyes greyish-green in life. Labium pale yellow. Face ( Fig. 4 ): mandible bases, labrum, anteclypeus, postclypeus and frons pale yellow. Vertex black, antennae black.

Thorax yellowish-brown with black pattern ( Fig. 5 ). Prothorax black with yellow middle stripe on dorsum and brown marks on sides of middle lobe; synthorax yellowish-brown with broad dark brown stripes along humeral suture and metapleural suture, and broad yellow marks on mesepimeron and metepimeron. Legs black except coxae brown.

Wings ( Fig. 5 ) hyaline, venation black. Arculus at 2nd antenodal. Antenodals 14 in both FW; 11 in both HW; postnodals 12 in both FW, 14 (left)–13 (right) in HW. One cubito-anal vein in all wings. Triangles crossed with 1 (left)–2 (right) in FW; 1 in both HW. Pterostigma black, overlying one and a half cells in all wings.

Abdomen black with yellow markings ( Fig. 5 ). S1–2 with middorsal broad stripes and large markings laterally. S3 strongly pruinose dorsally with markings laterally. S4–7 with a pair of long triangular middle dorsal spots and little crescent spots laterally, base of S4 also pruinose. S8 with a pair of small middle dorsal crescent spots on the base and small spots laterally. S9–10 wholly black. Caudal appendages simple and robust. Cerci black, twice as long as S10. Epiproct black, as long as S10 ( Fig. 8 ).

Secondary genitalia ( Fig. 9 ). Black. Anterior lamina long, pointed ventrally, divaricate at tip; anterior hamule reduced; posterior hamule robust, oblique shovel shaped, with a short strong tooth on ventral margin.

Measurements (mm): Total length 49.5; abdomen + appendages 31.9; hind wing 38.3.

Variation in paratypes. ( Figs. 6–7 )

Measurements (mm): Total length 49.1–51.5; HW 38.9–41.1; abdomen + appendages 33.1–35.2.

Antenodals 14–15 in FW; 10–12 in HW; postnodals 10–13 in FW, 12–14 in HW. Pterostigma overlying 2.5–3 cells. The yellow markings on body of specimen ccr0181 is obviously more distinct than others implying that it is younger. The scope of pruinosity on abdomen dorsum from restricting to S3 (ccr0181) to covering the basal half of S3–4 (ccr0193). Anterior lamina pointed ventrally as the holotype ( Fig. 9 d ) as in ccr0179 ( Fig. 9 e ) but straight bent backwards in ccr0181 and ccr0193 ( Fig. 9 c, f ).

Description of female based on photographs. Body yellow with black markings ( Figs. 10–11 ).

Head. Eyes greyish-green in life. Labium yellow. Face: mandible bases, labrum, anteclypeus, postclypeus and frons yellow. Vertex black, antennae black.

Thorax. Prothorax black with yellow middle stripe on dorsum and yellow markings on middle lobe laterally; synthorax yellowish-brown dorsally, yellow laterally with black stripes along humeral suture, metapleural suture, and interpleural suture. Legs black except coxae brown.

Wings hyaline, venation black. Arculus at 2nd antenodal. Antenodals 15 in both FW, 11 (left)–10 (right) in HW; postnodals 11 in both FW, 11 (left)–12 (right) in HW. One cubito-anal vein in all wings. Triangles crossed with 1 in both FW and both HW. Pterostigma black, overlying two cells in all wings.

Abdomen black with yellow markings. S1–2 with large middle markings dorsally and markings laterally. S3–S8 with a pair of long triangular middle markings and crescent edge spots dorsally, large markings laterally; S3 and base of S4 moderately pruinosed dorsally. S9–10 wholly black. Cerci yellow dorsally, black laterally, a little longer than S10.

Diagnosis. The male of O. aberrans most resembles the male of O. albistylum , but differs in the yellow markings and the pruinose pattern, and also the blackish cerci. The pale markings on abdomen of younger male of O. albistylum are large and pale brown in colour ( Fig. 12 ) whereas they are relatively small and yellow in O. aberrans ( Fig. 5 ). The pruinosity on mature males of O. albistylum covers S3–6, with S7–10 wholly black ( Fig. 13 ). But the pruinosity covers S3–4, with only S9–10 wholly black in O. aberrans ( Fig. 7 ). According to photos from an observer, one aged male of O. aberrans is pruinose extending to S6, therefore it is even more similar to O. albistylum . However, the pruinosity on S5–6 of this male is restricted to the margin and very light, with the yellow markings underneath visible. On the other hand, the female is similar to O. cancellatum ( Fig. 14 ), but differs in the relative smaller yellow markings on abdomen, the finely pruinosed S3–4, the wholly blackish S9–10, and the distinct white dorsal colour on the cerci ( Fig. 11 ). The female is also similar to O. triangulare in appearance but differs in the relative pale and narrow black stripes on the synthorax, the relative smaller yellow markings on abdomen which are all rectangular in the latter, the finely pruinosed S3–4, and the blackish S9–10 which extended to S8–S 10 in the latter. The shape of the male secondary genitalia can separate O. aberrans from both O. albistylum and O. cancellatum easily depending on the generally shorter of posterior hamule and the smaller end tooth ( Fig. 9 c–f ). In the other two species the posterior hamule is generally longer vertically and the end tooth is rather longer ( Fig. 9 a–b ). Note that in terms of the shape of posterior hamule, O. albistylum and O. cancellatum are very similar.

Distribution and habitat

Orthetrum aberrans has been reported from China including Beijing, Chongqing, Guizhou, Henan, Hubei, Liaoning, Shanxi, Sichuan, and Tianjin, at an altitude scope from 600 m to 2100 m. Its distribution could be roughly characterised as restricted to Northwest China but far from coastal areas of Southeast China. Although each locality may house populations, those were relatively large and stable in localities of Chongqing, Shanxi, and Sichuan. Orthetrum aberrans usually occurs in mountains with still but clear waters ( Fig. 15 ). It usually lives together with other congeners such as O. albistylum , O. triangulare etc., and interacted (fighting between males or even trying to chase and copulate with females of other species) with them intensively. However, I did find a pure population of O. aberrans in Chongqing with rather big individual numbers where this species was the sole Orthetrum species. As in other Orthetrum species, males of O. aberrans often patrol over the water surface, fighting frequently with both intraspecific and interspecific rivals, whereas females are difficult to see. During flight, the white coloured waist of the male, caused by the pruinosity, is very apparent in sunlight and can be used to easily separate it from other species ( Fig. 4 ).

Figures

FIGURE 4. The holotype in life, flying.

FIGURE 5. The holotype in life, at rest.

FIGURE 6. Paratype ccr0179 in life, at rest in frontal view.

FIGURE 7. Paratype ccr0179 in life, at rest in lateral view.

FIGURE 8. Male caudal appendages of Orthetrum aberrans (holotype) in dorsal (a) and lateral view (b).

FIGURE 9. Male secondary genitalia of Orthetrum spp. (a), O. albistylum (b), O. cancellatum (c), O. aberrans, ccr0181 (d), O. aberrans, ccr0178 (e), O. aberrans, ccr0179 (f), O. aberrans, ccr0193.

FIGURE 10. Female of Orthetrum aberrans in life, lateral view, photographed by Yuting Liu.

FIGURE 11. The same female of Orthetrum aberrans in dorsal view, photographed by Yuting Liu.

FIGURE 12. A younger male of Orthetrum albistylum, in life.

FIGURE 13. A mature male of Orthetrum albistylum, in life.

FIGURE 14. Female of Orthetrum cancellatum, in life, photographed by Hongguang Jin.

FIGURE 15. Type locality of Orthetrum aberrans from Wushan, Chongqing.