Trithemis legrandi Dijkstra, Kipping & Mézière, 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 : 652-656

Trithemis legrandi Dijkstra, Kipping & Mézière sp. nov. – Robust Dropwing

(Type Photo 56, Photos 2, 72, Fig. 33)

Taxonomy

Dijkstra (2007) diagnosed the basitincta -group of Trithemis (see below) and its similar species T. basitincta Ris, 1912 and T. bifida Pinhey, 1970 . However, males from Makokou in north-eastern Gabon identified as T. bifida by Jean Legrand in MNHN pertain to neither species, and similar individuals occur with both in south-eastern Gabon. Although available COI evidence is limited, the morphological distinction is sufficient to describe this species, based also on material from extreme south-western Cameroon. Damm et al. (2010) found a small difference with T. bifida in ND1, 16S and ITS; the two species together forming the sister-group of T. basitincta .

Material studied

Holotype ♂. Cameroon, South Province, 26 km E of Campo, Campo-Ma’an National Park (buffer zone), Bitandé River 1 km E of Nkoélon , rocky rainforest river ( Photo 72) and adjacent roadsides, 70–100 m a.s.l. (2.3940 ° N 10.0540 ° E), 15 -vi- 2008, leg. K.-D.B. Dijkstra, J. Kipping & K.Schütte, RMNH . Further material. CAMEROON (South Province): 2 ♀, as holotype, CJKL . 1 ♀, locality as holotype, 13 -vi- 2008, leg. K.-D.B. Dijkstra, J. Kipping & K. Schütte, RMNH . GABON (Haut-Ogooué Province): 1 ♂ ( RMNH.INS.508171 ), 1 ♀ ( RMNH.INS.508175 ), 38 km SE of Franceville, Franceville- Kessala Road, 3 rd stream E of Onkoua , gravelly stream in rainforest, 411 m a.s.l. (1.8551 ° S 13.8620 ° E), 09-i- 2010, leg. K.-D.B. Dijkstra, N. Mézière & C. Vanappelghem, RMNH . 1 ♂ 4 ♀, Concession Rougier, plot L 21 A on road to Franceville, 10 km after Moanda, Moyabi , sandy stream (1 m wide, 20– 50 cm deep), 377–398 m a.s.l. (1.7390 ° S 13.2977 ° E), 14–28 -x- 2010, leg. N. Mézière, RMNH . 2 ♂ 1 ♀, Concession Rougier, Moanda, sandy stream ( Photo 2) (3–4 m, 50 cm deep), 411 m a.s.l. (1.7051 ° S 13.3560 ° E), 26 -iv- 2009, leg. C. Vanappelghem & N. Mézière, RMNH . 1 ♂ 1 ♀, Moanda-Mounana road, Mbéréssé bridge, Nguiassono , sandy stream (2 m wide, 30 cm deep) with rapids and rocks, 420 m a.s.l. (1.4953 ° S 13.1800° E), 08-i- 2011, leg. N. Mézière, RMNH . 1 ♀, Franceville-Okondja road, 2 km before Okila , muddy and gravelly stream in forest (4 m wide, <50 cm deep), 364 m as.l. (1.0790 ° S 13.5669 ° E), 23 -ix- 2010, leg. N. Mézière, RMNH . 1 ♀ ( RMNH.INS.508897 ), same locality, 14 -x- 2013, leg. N. Mézière, RMNH . 1 ♂, Franceville-Okondja road, 1 km after Ondzei , muddy river (silted from laterite of road) bordered by dammed ponds, 351 m a.s.l. (0.7317 ° S 13.5970 ° E), 13 -iii- 2011, leg N. Mézière, RMNH . 1 ♂, Bongoville-Léconi road , swamp close to Boubou Riv- er, 421 m a.s.l. (1.6116 ° S 13.9116 ° E), 30 -x- 2010, leg. N. Mézière, RMNH . GABON (Ogooué-Ivindo Province): 1 ♂, Okondja-Makokou road, 5 km SE of Bakouaka , sandy forest stream, 531 m a.s.l. (0.1298 ° N 13.6772 ° E), 23 - ix- 2014, leg. J. Kipping, CJKL . GABON (Estuaire Province): 1 ♂ ( RMNH.INS.508734 ), Kougouleu-Medouneu road, Monts de Cristal, Assegone-Essala , mountain stream with rapids and small falls, 2–4 m wide, 50 cm deep (0.5596 ° N 10.2362 ° E), 28 -xii- 2012, leg. N. Mézière & J. Lekogo, RMNH .

Genetics

Two unique haplotypes (n = 4) are very similar to six of T. bifida (n = 11) and the two species are potentially inseparable.

Male morphological diagnosis

Belongs to the basitincta -group by the combination of (a) Fw discoidal field of 3 rows at base; (b) 4–6 cell-doublings in radial planate and thus two rows of cells there; (c) hamule with long sickle-shaped hook; and (d) the genital lobe directed away from the hamule ( Fig. 33). Nearest to the sympatric T.basitincta and T. bifida by (e) the fairly large size, Hw 31.8–33.5 mm (n = 4); (f) 13 ½– 16 ½ Ax in Fw; (g) the large and dark patch at Hw base that fills the cubital space to beyond Cux and extends into the anal field, thus appearing triangular and nearest to T. basitincta as Fig. 6 s in Dijkstra (2007), although sometimes also present in the subcostal space proximal to Ax 1; (h)the parallel-sided anterior lamina with a broad and deeply-notched apex; and (i) the notably slender and sabre-like hamules ( Fig. 33). Only separated reliably by (1) the apical peaks of the anterior lamina that in lateral view are not dark and pointedly rounded, but have pale flat-topped swellings, which in caudal or rostal view may appear to close the top of the cleft between them. The swelling is greater and the cleft completely closed in the sympatric T. aconita Lieftinck, 1969 and T. congolica Pinhey, 1970 , while T.tropicana Fraser, 1953 has a fairly flat but neither swollen nor cleft anterior lamina ( Fig. 33). Also is (2) shorter-bodied, Hw being 79–82 % of full length rather than 73–78 %; and (3) as males darken with age, the pale markings remain visible last ventrally on S 4–7, while any visible dorsal markings lie on the lateral carina and are shorter than half the segments’ length. The dorsal markings that are visible last in T. bifida lie closer to the dorsal than lat- eral carinae and extend over almost the full segment length. The markings are intermediate in T. basitincta , with the rather short final markings lying about halfway the dorsal and lateral carinae. That species, however, can be separated by the presence of short bristles rather than long hairs at the base of the anterior lamina ( Fig. 33). Trithemis legrandi also often has large and distinct lateral yellow spots on the labium, postclypeus and frons even in very dark specimens, e.g., those virtually lacking pale abdominal markings.

Etymology

Named in honour of Dr Jean Legrand, collector of the first material of this species, and successor to Elliot Pinhey as the leading specialist of African Odonata of his time (masculine genitive noun).

Range and ecology

Sandy, gravelly and rocky streams and small rivers in rainforest between 50 and 500 m a.s.l. in Gabon and southern Cameroon. Males fly rapidly over water but rarely perch by the streams.