Eleuthemis eogaster Dijkstra

Dijkstra, Klaas-Douwe B., Kipping, Jens & Mézière, Nicolas, 2015, Sixty new dragonfly and damselfly species from Africa (Odonata), Odonatologica 44 (4), pp. 447-678 : 610-615

Eleuthemis eogaster Dijkstra sp. nov. – Sunrise Firebelly (Type Photo 44, Photo 58, Fig. 28)

Taxonomy

The genus Eleuthemis Ris, 1910 has generally been treated as monotypic ( Dijkstra 2007), although Lempert (1988) noted males with differently coloured abdomen undersides and distinct habitat preferences occurring together in Liberia. As the abdomen’s bright white back and coloured underside are used in display behaviour, the two forms may represent distinct species, which is confirmed by genetic data (see E. umbrina sp. nov.). Moreover, at least five other distinct genetic clusters are apparent within Eleuthemis that also overlap partly geographically and differ in coloration ( Tree 7). The morphologically most distinct clades are named here, bringing the genus to five species, although we believe at least three more exist: two co-occurring in Gabon appear as rather dark E. buettikoferi Ris, 1910 and E.umbrina respectively, while that from Katanga , Tanzania and Zambia looks like a paler E. buettikoferi ( Map 9). Typical E. buettikoferi Ris, 1910 occurs from Sierra Leone east at least to Ghana and has (1) a thick black border to the labrum; (2) Fw with darkened tip that just touches the distal end of Pt; (3)the vertex and occipital triangle blackened at least basally; (4)Fw discoidal field entirely of two or more rows of cells; (5) the abdomen dorsum entirely whitish pruinose with maturity; (6) the abdomen underside largely orange, at least S 6–9 without black on the ventral carinae; (7)largely blackish secondary genitalia; and (8) an acute tip to the hook of the hamule ( Fig. 28). Pinhey (1974) described E. b. quadrigutta from only two females from the Zimbabwe-Mozambique border, yet later raised it to species level ( Pinhey 1984). Dijkstra (2007) synonymised it with E. buettikoferi on account of the variation in what was then considered a monotypic species. However, recent topotypical males are genetically distinct ( Tree 7) and unique within the genus by (1) the very distinct dark tip to Hw as well as Fw; (2) the black-rimmed orange epiproct that contrasts with the wholly black cerci, rather than both being either all dark or partly orange; and (3) the presence of a second ventral tooth somewhat basal to the tooth on the thickening of the cerci. Thus E. quadrigutta Pinhey, 1974 must be treated as a distinct species. The taxon treated here is also genetically distinct ( Tree 7), has abdominal coloration unlike any other dragonfly known, and was illustrated by Dijkstra & Clausnitzer (2014) as a good species.

Material studied

Holotype ♂. RMNH.INS.559490 , Angola, Uíge Province, 8 km N of Quitexe, Lumanie river (tributary of Loge) near Quitoque, just E of Quitexe- Uíge road , forested sandy and stony river in farmbush, 677 m a.s.l. (7.8654 ° S 15.045 ° E), 30 -ix- 2013, leg. K.- D.B. Dijkstra, RMNH .

Further material. ANGOLA (Uíge Province): 4 ♂ ( RMNH.INS.559503 ), 1 ♀ ( RMNH.INS.559488 ), as holotype, RMNH . 6 ♂ ( RMNH.INS.508344 , RMNH.INS.508347 ), 14 km WSW of Uíge, Loge valley, Loge River and two side streams , large murky river and two clear streams in degraded lowland rainforest, 602 m a.s.l. (7.6701 ° S 14.9381 ° E), 22 -xi- 2012, leg. K.-D.B. Dijkstra, RMNH . 1 ♂, same locality, 03-x- 2013, leg. K.-D.B. Dijkstra, RMNH . 1 ♂ ( RMNH.INS.508296 ), 9 km W of Uíge, new campus site and environs, Cazenga stream SW of Cunga-Quiximba , large murky stream in farmbush, 789 m a.s.l. (7.6196 ° S 14.9754 ° E), 16 -xi- 2012, leg. V. Clausnitzer & K.-D.B. Dijkstra, RMNH .

Genetics Seven unique haplotypes (n = 8) nearest to two from Gabon whose coloration recalls E. umbrina ( Tree 7). Male morphological diagnosis

Morphologically like E. buettikoferi by (a) the moderate size, Hw 25.2– 26.5mm (n= 3); (b) the distinct black border to labrum; (c) Fw with darkened tip that just touches distal end of Pt; (d) the Fw discoidal field entirely of two or more rows of cells; (e) the largely orange underside of the abdomen; (f) the largely blackish secondary genitalia; and (g) the acute tip to the hook of the hamule (like Fig. 28). However, (1) the middorsal section of the mesepisterna is brown, distinctly lighter than the blackish lateral thoracic stripes, thus contrasting weakly with the pale ante-humeral stripes; (2) the largely bright orange abdominal dorsum is unique, with S 2–3 bearing basal brown smudges, S 4–5 pairs of dark subbasal spots, S 6–8 two sublateral black bands, while S 9–10 are (largely) black, and the dark markings on S 4–6 and sometimes base of S 7 become covered by white pruinosity with maturity; and (3) the cerci are orange at their base, contrasting with the largely to wholly black epiproct.

Etymology

Greek “dawn belly” refers to the unique abdominal coloration, akin to a sky with white clouds at sunrise (noun in apposition).

Range and ecology

Common on larger streams and small rivers, typically bordered by forest, between 600 and 800 m a.s.l. south and west of Uíge in northern Angola.