Paragomphus darwalli Dijkstra, Mézière & Papazian, 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 : 592-596

Paragomphus darwalli Dijkstra, Mézière & Papazian sp. nov. – Darwall’s Hooktail

(Type Photo 39, Photos 51–52, Fig. 23)

Taxonomy

See general rationale for the dark forest Paragomphus species under P. c l a u s ­ nitzerorum sp. nov. Recalls P. tournieri Legrand, 1992 from western Africa, the only other largely black African Paragomphus species with parallel cerci, but genetically distant and morphologically distinct (Tree 6).

Material studied

Holotype ♂. RMNH.INS.502500 , Gabon, Haut-Ogooué Province, 34 km E of Franceville, Franceville-Léconi Road, NE of Bongoville , 417 m a.s.l. (1.6130 ° S 13.9055 ° E), 31 -xii- 2009, leg. K.-D.B. Dijkstra, RMNH .

Further material. ANGOLA (Cuanza Norte Province): 1 larva ( RMNH.INS.559485 *), 16 km WNW of Camabatela, Quitexe-Camabatela road, Seque stream near Bindo , partly forested sandy and muddy stream, 810 m a.s.l. (8.1634 ° S 15.2209 ° E), 29 -ix- 2013, leg. K.-D.B. Dijkstra, RMNH . GABON (Haut-Ogooué Province): 1 ♂ ( RMNH.INS.503361 *), Bakoumba Riv- er between Bakoumba-Ville and -Village , sandy river in rainforest, 544 m a.s.l. (1.8576 ° S 13.0148 ° E), 02-i- 2010, leg. N. Mézière, RMNH . 1 ♀ ( RMNH.INS.554437 *), Bakoumba road, Kounda, Mbéressé , sandy forest river, partly open and sunny (3 m wide, 50–100 cm deep), 484 m a.s.l. (1.5859 ° S 13.1563 ° E), 06-x- 2012, leg. N. Mézière, RMNH . 1 ♂ ( RMNH.INS.554542 ), 1 ♀ ( RMNH.INS.554538 ), Bongoville-Léconi road, Boubou River, Ekala , sandy forest stream (1–2 m wide, 5–10 cm deep), muddy edges, 427 m a.s.l. (1.6133 ° S 13.9125 ° E), 09-xii- 2012, leg. N. Mézière & J. Lekogo, 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), 20 -ix- 2009, leg. N. Mézière, RMNH . 1 ♂, same locality, 07-ii- 2010, leg. N. Mézière, RMNH . 1 ♂ ( RMNH.INS.508863 ), 2 ♀ ( RMNH.INS.508882 ), Batéké Plateau, Léconi Valley, Eaux Claires, Camps des Pygmés , sandy streams (1 m and 4–5 m wide) at forest edge, 434 m a.s.l. (1.4549 ° S 14.1785 ° E), 28 -ix- 2013, leg. N. Mézière, J. Kipping & H. Krahnstöver, RMNH . 1 ♀ ( RMNH.INS.508777 ), same locality, 10 -iii- 2013, leg. N. Mézière, RMNH . 1 ♀ ( RMNH.INS.508097 *), Moyabi, 17 km SSE of Moanda (1.7082 ° S 13.2518 ° E), 01-x- 2013, leg. N. Mézière, RMNH . 1 adult ( RMNH.INS.506208 ), no further locality data, i– iv- 2012, leg. N. Mézière, RMNH .

Genetics

The holotype belongs to a cluster of five unique haplotypes (n = 7). Specimens marked with a star above form a second cluster of four unique haplotypes (n = 4), whose sister-group relationship with the first is poorly supported, but we have no morphological arguments to separate them specifically. The relationships of these distinct clusters with further species are also weakly supported (Tree 6).

Male morphological diagnosis

Recalls P. tournieri by (a) the largely black face and occiput; (b) the largely black thorax with prominent green postdorsal, mesepimeral and metepimeral stripes, but almost entirely reduced ante-humeral and metepisternal stripes; (c) the postdorsal stripes that are clearly separated from the collar; (d) the cerci that in dorsal view are parallel to each other to their end; and (e) the cerci that in lateral view are strongly and evenly curved, like a walking cane, and terminate in blunt tips ( Fig. 23). However, (1) notably small, Hw 21.5 –22.0 mm (n = 4) rather than 23.5 –24.0 mm (n= 2); (2) the labrum is uniformly brown, becoming even a fraction paler towards the border, rather than black and darkest on the border enclosing a green bar; (3) the ante-humeral stripe is absent, rather than reduced to a spot that lies close to the dorsal end of the postdorsal stripe; (4) the curved section of the cerci is longer and more slender; and (5) the tips of cerci may bear a small subapical spine, although possibly this breaks off easily in either species ( Fig. 23).

Etymology

Named in honour of Dr William Darwall, head of the IUCN Freshwater Biodiversity Unit (masculine singular genitive noun). Darwall and his team were instrumental in synthesising the threat status of Africa’s aquatic nature. Such facilitators are the unsung heroes of conservation efforts worldwide.

Range and ecology

Clear sandy streams in gallery forest between 350 and 550 m a.s.l., especially around the Batéké Plateau in south-eastern Gabon. Males were found in forest clearings and on small sand banks in the streams. The record of a genetically similar larva at 810 m a.s.l. in northern Angola requires confirmation (Tree 6).