Ceriagrion obfuscans Dijkstra, Mézière & Kipping, 2015

Dijkstra, Klaas-Douwe B., Kipping, Jens & Mézière, Nicolas, 2015, Sixty new dragonfly and damselfly species from Africa (Odonata), Odonatologica 44 (4), pp. 447-678 : 515-518

Ceriagrion obfuscans Dijkstra, Mézière & Kipping sp. nov. – Darkening Citril

(Type Photo 17, Photos 18, 25–26, 39–40, 52, Fig. 11)

Taxonomy

Belongs to the genetically, morphologically and ecologically distinct varians -group of Ceriagrion , which aside from C. annulatum Fraser, 1955 and C.rubellocerinum Fraser, 1947 includes C. platystigma Fraser, 1941 that Dijkstra (2005 a) synonymised with C. varians (Martin, 1908) . The latter two are similar by (a) the never blackened head and only occasionally blackened S 3–7; (b) the apex of S 10 with fine and often almost indiscernible black denticles; and (c)the narrow cerci that are at most as wide as long, with at most their apical teeth touching ( Fig. 11). However, C. platystigma is distinguished by (1)the labrum and thorax being pale brown to deep red, rather than orange; (2) the red Pt and S 3–7 can become (at least partly) black; (3) the penis’ short apex that does not reach the bend of its stem in lateral view; and (4) the cerci being separated by a space that is somewhat wider than their width, with the apical teeth wide apart in dorsal view ( Fig. 11) [rejected synonymy]. The synonymy of C. sanguinostigma Fraser, 1955 with C. varians (Martin, 1908) was reconfirmed in MRAC. The new species is the most distinct one in the group and was treated as such by Dijkstra & Clausnitzer (2014), overlapping geographically with all other group species except possibly C.rubellocerinum .

Material studied

Holotype ♂. Congo-Kinshasa, Province Orientale, Lower Lomami, Iloko stream on Lieki-Lileke path , swampy blackwater stream, 390 m a.s.l. (0.6548 ° N 24.2685 ° E), 27 -v- 2010, leg. K.- D.B. Dijkstra, RMNH .

Further material. CONGO-KINSHASA (Province Equateur): 2 ♂ 4 ♀ ( RMNH.INS.502151 ), Lower Itimbiri, Loeka River (= Gwolo) mouth , tributary, forest and Itimbiri around mouth, 360 m a.s.l. (2.038 ° N 22.826 ° E), 16 -v- 2010, leg K.- D.B. Dijkstra, RMNH . 2 ♀, Lower Itimbiri, Lokeke and Liha streams on Engengele-Yamoenga road , swampy streams in farmbush, 375 m a.s.l. (2.11 ° N 22.69 ° E), 13 -v- 2010, leg K.- D.B. Dijkstra, RMNH . 1 ♀, Lower Itimbiri, Kona forest , swamp forest, 362 m a.s.l. (2.040 ° N 22.788 ° E), 12 -v- 2010, leg. K.- D.B. Dijkstra, RMNH . 1 ♀, Lower Itimbiri, Loeka Riv- er (= Gwolo), lower 3 km of blackwater tributary , 375 m a.s.l. (2.05 ° N 22.82 ° E), 11 -v- 2010, leg. K.- D.B. Dijkstra, RMNH . CONGO-KINSHASA (Province Orientale): 6 ♂ ( RMNH.INS.502141 ), 2 ♀, as holotype, RMNH . 1 ♂ 2 ♀, Lower Lomami, Lieki camp, river bank and adjacent forest and farmbush , 420 m a.s.l. (0.685 ° N 24.240 ° E), 28 -v–02-vi- 2010, leg. K.- D.B. Dijkstra, RMNH . 3 ♂ 2 ♀ ( RMNH.INS.502301 ), E of Isangi, Yandja River to Yandja Lac (= Etang Loholo) , farmbush, swamp forest and blackwater lake, 385 m a.s.l. (0.73 ° N 24.28 ° E), 06-v- 2010, leg. K.- D.B. Dijkstra, RMNH . 22 ♂ ( RMNH.INS.502198 , RMNH.INS.502278 , RMNH.INS.502300 ), 6 ♀ ( RMNH.INS.502286 ), 2 ♂ ♀, between Yangole and Yaeoli on Yaekela-Lilanda road , blackwater swamp forest, 376 m a.s.l. (0.8017 ° N 24.2978 ° E), 03– 05-v- 2010, leg. K.- D.B. Dijkstra, RMNH . 3 ♀ ( RMNH.INS.502188 , RMNH.INS.502196 ), Yaekela, flooded forest and farmbush ( Photo 39), 410 m a.s.l. (0.81 ° N 24. 28 ° E), 01–02-v- 2010, leg. K.-D.B. Dijkstra, RMNH . 1 ♂, Low- er Lomami, research transect at Ekukumu camp near Yabogesa , river bank and adjacent forest and farmbush, 350 m a.s.l. (0.6804 ° N 24.1903 ° E), 30 -v- - 2010, leg K.-D.B. Dijkstra, RMNH . GABON (Haut-Ogooué Province): 1 ♂ ( RMNH.INS.554374 ), Batéké Plateau, Léconi Valley, Eaux Claires, Camps des Pygmés , swamp and forest along a sandy river, 434 m a.s.l. (1.4549 ° S 14.1785 ° E), 16 -ix- 2012, leg. N. Mézière, RMNH . 1 ♂, Batéké Plateau, Léconi Valley, Eaux Claires , forest swamp, 440 m a.s.l. (1.4543 ° S 14.1747 ° E), 26 -i- - 2012, leg. N. Mézière, A. Günther, J. Kipping & H. Krahnstöver, RMNH . 1 ♂, Léconi road 5 km after Bongoville, Sablière d’Ekala , forest swamp, 393m a.s.l. (1.6068 ° S 13.9137 ° E), 07-xi- 2010, leg. N. Mézière, RMNH . 12 ♂, Batéké Plateau, 18 km NW of Léconi , sandy stream and swamp in dense gallery forest, 425 m a.s.l. (1.4472 ° S 14.1661 ° E), 29 -ix- 2013, ( Photo 25) leg. J. Kipping, CJKL . 3 ♂ 1 ♀, same locality, 20 -ix- 2014, leg. J. Kipping, CJKL .

Genetics Four unique haplotypes (n = 10) are very distinct but nearest to the rest of the varians -group. Male morphological diagnosis

Medium-sized damselfly (Hw 20.0–22.0 mm; n = 16) that belongs to the varians -group by (a) the blackish rhomboidal Pt with the anterior border shorter than the posterior; (b) the cerci that are wider than long and (almost) touch each other in dorsal view; and (c) the paraprocts without a heeled lower border in lateral view ( Fig. 11). However, unlike other group species, (1) the orange to red head, thorax and S 1–2 blacken with age; (2)the humeral and metapleural sutures lack dark dots in the fossae, although this character is obscured with the darkening of the body; (3) the penis has a notably long, broad and squarish apex and lacks small horn-like cones on each side of its base; (4) S 3–10 are always blackish, while at least S 8–10 always remain red in other species; (5) the cerci are round rather than pointed in lateral view; and (6) the paraprocts are just over twice as long as the cerci, rather than under ( Fig. 11).

Etymology

Latin “making dark” refers to the body that blackens with age and the gloomy habitat (present participle of obfusco used as adjective).

Range and ecology

Unlike most Ceriagrion species, the varians -group prefers rainforest shade. The new species favours deeply shaded standing water with thick detritus between 350 and 440 m a.s.l., often blackwater, probably mostly temporary (e.g., flooded by river water) and typically on sand, e.g., in Gabon known only from the Batéké Plateau ( Photo 26). It can be the most abundant odonate in dark flooded forest in the Congo Basin ( Photo 39). Conspicuously orange when fresh, adults darken and become increasingly inconspicuous with age.