Zygonyx dionyx Dijkstra & Meziere, sp. nov.
Creators: name: Dijkstra, Klaas-Douwe B.
name: Kipping, Jens
name: Mézière, Nicolas
Publisher: name: Zenodo
Year: 2015
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Odonata
Libellulidae
Zygonyx
Zygonyx dionyx

description: Zygonyx dionyx Dijkstra & Mézière sp. nov. –
Eastern Double-hooked Cascader
(Type Photo 60, Photo 26, 56, Fig. 35)
Taxonomy
Part of the flavicosta -complex of Zygonyx Hagen, 1867 (see Z. annika sp. nov.). Genetics and the distinct morphology of its secondary genitalia suggest it is the eastern counterpart of the Upper Guinea endemic Z. geminuncus (Tree 10).
Material studied
Holotype ♂. RMNH.INS.508872, Gabon, Haut-Ogooué Province, Batéké Plateau, Léconi Valley, Eaux Claires, Camps des Pygmés, sandy river (4 m wide, 20–200 cm deep) in gallery forest bordered by swamp, 434 m a.s.l. (1.4549 ° S 14.1785 ° E), 29 -ix- 2013, leg. N. Mézière, J. Kipping & H. Krahnstöver, RMNH.
Further material. GABON (Haut-Ogooué Province): 1 ♂, locality as holotype, 16 -ix- 2012, leg. N. Mézière, RMNH. 1 ♂, Bongoville-Léconi road after Ekala, old village of Boubou, stream (2 m wide) with gravel bottom, 393 m a.s.l. (1.6114 ° S 13.9105 ° E), 17 -iv- 2011, leg. N. Mézière, RMNH. 1 ♂ (RMNH.INS.508075), Batéké Plateau, 18 km NW of Léconi, sandy stream in dense gallery forest, tributary to Léconi River, 425 m a.s.l. (1.447218 ° S 14.166175 ° E), 29 -ix- 2013, leg. J. Kipping, CJKL. 1 ♂, same locality, 30 -ix- - 2013, leg. J. Kipping, CJKL.
Genetics
Two unique haplotypes (n = 3) that are nearest to Z. annika and Z. geminuncus (Tree 10).
Male morphological diagnosis
Belongs to the flavicosta -complex by (a) the modest size, Hw 36.0– 38.5 mm (n = 3); (b) the moderately dense venation, with 11 ½– 12 ½ Ax in Fw; (c) the largely black hind legs; and (d) the pale subapical band on the dorsum of S 7 that stands out against largely dark S 5–6. Most similar to the probable sister-species Z. geminuncus with (e) the apex of the anterior lamina being constricted and incised to form a pair of triangular forward-curved hooks; and (f) the hamule with a low lobe and narrow base making its hook appear longer (Fig. 35). However, (1) the anterior lamina is not swollen and raised laterally of the apical hooks to eclipse them in lateral view; (2) the apical hooks of the the anterior lamina are relatively large; (3) the hamule has a less tapering base; and (4) the epiproct is longer with a narrower tip (Fig. 35).
Etymology
Greek “two claws” in parallel to Latin “twin claw” of western counterpart Z.geminuncus and matching the generic name (noun in apposition).
Range and ecology
Sandy and very clear tributaries of the Léconi River at about 400 to 435 m a.s.l. on the Batéké Plateau in south-eastern Gabon, which meander through dense gallery forest surrounded by open grasslands (Photos 26, 56). As for Z. geminuncus, these sites are much shadier than preferred by other Zygonyx species, including Z. flavicosta, and males hover very low over rapid sections at the few sun spots present.
description: Published as part of Dijkstra, Klaas-Douwe B., Kipping, Jens & Mézière, Nicolas, 2015, Sixty new dragonfly and damselfly species from Africa (Odonata), pp. 447-678 in Odonatologica 44 (4) on pages 669-671, DOI: 10.5281/zenodo.35388