Pseudagrion dactylidium Dijkstra & 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 : 524-527

Pseudagrion dactylidium Dijkstra & Mézière sp. nov. – Gabon Slim Sprite

(Type Photo 19, Photos 29–30, Fig. 13)

Taxonomy

Belongs to the “slim sprites”, a group of slight rainforest Pseudagrion Agroup species that perch in a hanging position and favour sandy streams ( P.cyathiforme Pinhey, 1973 and P. simplicilaminatum Carletti & Terzani, 1997 ) or soft-bottomed ponds, seeps and headwaters ( P. hemicolon Karsch, 1899 and P. thenartum Fraser, 1955 ). The present taxon is probably the sister-species of the similar and sympatric P. thenartum , but separated by the male appendages.

Material studied

Holotype ♂. RMNH.INS.502449 , Gabon, Haut-Ogooué Province, righthand road before “Africa No 1 ” radio station in the direction of Franceville, Moyabi , swamps in forest, 482 m a.s.l. (1.6866 ° S 13.3076 ° E), 19 -v- 2011, leg. N. Mézière, RMNH .

Further material. GABON (Haut-Ogooué Province): 1 ♂, locality as holotype, 21 -i- 2011, leg. N. Mézière, RMNH . 1 ♂, same locality, 11 -ii- 2011, leg. N. Mézière, RMNH . 4 ♂, same locality, 0 9–10 -iii- 2011, leg. N. Mézière, RMNH . 3 ♂ ( RMNH.INS.502435 , RMNH.INS.502449 ), 8 km SW of Moanda, Mouyeugue-Moanda-Bakoumba Road, Mbéréssé River at Mikouangna , sandy and turbid river in farmbush and associated (forested) swamp, 409 m a.s.l. (1.5925 ° S 13.1550 ° E), 13 -i- 2010, leg. K.-D.B. Dijkstra, RMNH . 2 ♂ ( RMNH.INS.503307 ), Moanda , shaded and well-vegetated (Maranthaceae) forest pool bordering stream, 423 m a.s.l. (1.5555 ° S 13.1195 ° E), 07-iii- 2010, leg. N. Mézière, RMNH . 1 ♂, Konda, 11 km W of Moanda , small sandy streams and pools in forest, 423 m a.s.l. (1.5555 ° S 13.1195 ° E), 30 -i- 2012, leg. J. Kipping, CJKL . 1 ♂, Moyabi, 18 km SE of Moanda , small pools in forest, 484 m a.s.l. (1.5858 ° S 13.15631 ° E), 24 -i- - 2012, leg. J. Kipping, CJKL .

Genetics

Two unique haplotypes (n = 3) nearest to P. hemicolon (n = 6; five unique haplotypes) and P. thenartum (n = 1).

Male morphological diagnosis

Similar to the sympatric P. hemicolon and P. thenartum by (a) the small size, Hw 20.5 –22.0 mm (n = 5); (b) the slender build; (c) the bright orange, though yellow when preserved, postocular spots and thorax, with broad ante-humeral stripes; (d) the largely pale legs; and (e) the reddish Pt, although also yellowish when preserved. Separated reliably from P. thenartum only by (1)the sleeker cerci in dorsal view, the distal section being distinctly narrower than the basal section with the lower flange largely reduced ( Fig. 13). This shape is intermediate between the also sympatric (but blue-bodied) P. simplicilaminatum and P. thenartum , in which the tip is at least as wide as the base and the flange is even wider and strongly rounded, often even more so than in Figure 13. Also differs from P. thenartum by (2) the blacker thorax, although there is overlap: the orange of the ante-humeral stripe typically touches the humeral suture over a shorter distance and does not cross to the mesepimeron at the posterior end of this suture, the wide part of the black humeral stripe thus appearing less pronounced, and there is always a black stripe along nearly the full length of the metapleural suture, which often reaches the metastigma and even metakatepisternum; the latter is typically ill-defined or even reduced to a black dot at the posterior end of this suture in P. thenartum .

Etymology

Latinised form of the Greek daktylidion (little finger) alludes to the shape of the cerci compared with P. thenartum , whose cerci Fraser (1955) likened to thumbs, even though thenar is Greek for the palm of the hand (noun in apposition).

Range and ecology

Deeply shaded and often temporary pools with thick detritus in rainforest between 400 and 500 m a.s.l. in south-eastern Gabon ( Photo 30). Pseudagrion thenartum appears never to be syntopic, favouring similar habitats near sandy springs and seeps.