Acisoma trifidum Kirby, 1889 —Pied Pintail

(Figs. 4 G, 5I, 6H, 7F, 8F, 10F)

Material. D.R. Congo: 3 males, Orientale, Yaekela, 01/ 02-v-2010, K.-D.B. Dijkstra (RMNH); 1 male, Orientale, 9 km E of Kisangani, Old Buta road, 09-vi-2010, K.-D.B. Dijkstra (RMNH); 1 male, Orientale, East of Isangi, Yandja Rive to Yandja Lac, 06-v-2010, K.-D.B. Dijkstra (RMNH).— Congo: 2 males, Region de Kouilou, Conkouati National Park, 21/ 22-ii-2010, P. Lambret (RMNH).— Liberia, 2 males, Mt Tokadeh, 29-ix / 02-x-2010 and 01-i-2011, K.-D.B. Dijkstra (RMNH); 1 male, northern bank Yah (Dayea) River near Gbapa, 05-i-2011, K.-D.B. Dijkstra (RMNH).— Angola: 1 male, 9 km WNW of Uíge, Cassanga stream and adjacent swamp, 17-xi-2012, V. Clausnitzer & K.-D.B. Dijkstra (RMNH); 1 male, 8 km SE of Negage, Gilangole stream, 25-xi-2012, K.-D.B. Dijkstra (RMNH).— Gabon: 1 male, Haut-Ogoué, Moanda, 24-iv-2009, N. Mézière & C. Vanappelghem (RMNH); 1 male, Haut-Ogoué, Plateau d’Okouma, Mounana, 01-vii-2009, N. Mézière (RMNH); 1 male, Moanda, 28-xi-2008, N. Mézière (RMNH).— Sierra Leone: 1 male, Eastern Province, Gola forest, 500 m north-east of Vaama, 08-iii-2011, K.- D.B. Dijkstra (RMNH).— Ghana: 1 male, Central Region, 12 km NW of Cape Coast, Brimsu Dam, 20-iv-2000, K.- D.B. Dijkstra (RMNH).— Benin: 1 male, 18 ESE of Zogbodomé, Sous-préfecture de Zogbodomé, Forêt de Lokoli, 09-vii-2002, S.L. Tchibozo (RMNH).— Gambia: 1 male, Brufut-Tanji, 16-xii-1980, M. Hämäläinen (RMNH).

Male diagnosis. The most distinctive species, confined to the more forested parts of equatorial Africa, with the following unique characters: (1) labrum black, only with two small white spots at base (Fig. 4 G); (2) labium black, only with two large white spots on sides (Fig. 5 I); (3) thorax largely black with limited and fragmented pale markings (Fig. 6 H); (4) mostly 3 cells in Fw triangle, but 43% of examined wings with 2 cells; (5) generally shorter Fw Pt, about 10–12% as long as Hw; (6) abdomen dorsoventrally rather than laterally compressed, narrowing most visibly in dorsal view and most marked on S7, thus only S8–10 slender, with S7–8 of similar and intermediate length as S6 and S9, rather than both distinctly longer (Fig. 7 F); (7) abdomen with solid and clean-cut white markings on S3–6, largely confluent across dorsal carina on S3–5, and bold ventral white spots on S4–5 (Fig. 7 F); (8) lobe of hamule narrow and pointed (Fig. 8 F). Similar only to A. ascalaphoides are the (9) more numerous Fw Ax, invariably 8½ or 9½.

Range and ecology. Occurs throughout western and central Africa, from Senegal to Uganda, Rwanda and northern Zambia, favouring more forested ponds than the frequently coexisting A. inflatum (Fig. 9 B).

high labrum is high; but high high

10% in 1 specimen

Labrum white, with one small white, with one small white, typically with tiny white, with one small all brown (Fig. 4) black spot at base black spot at base black spot loose of base, black spot at base but no spot in 38% and

basal black spot in 12%

…continued on the next page …continued on the next page Table 2. continued

Species (n=) A. variegatum (24) A. inflatum (31) A. panorpoides (26) A. attenboroughi (18) A. ascalaphoides (20) A. trifidum (20) Lateral carina S5 largely white largely or entirely black, largely or entirely black largely or entirely black entirely black entirely black Fig. 7) but largely white in 3%

Apical border of white distinctly skewed typically moderately rounded rounded rounded distinctly skewed marking on S6 (Fig. 7) dorsally skewed dorsally or ventrally

ventrally, but rounded

in 13%

(Fig. 7) with one large lateral with one large lateral with one large lateral with one large lateral with two small white typically no white spots, white spot white spot white spot white spot spots laterally but small dorsal spot in 10%

Base of S8 typically with two white always one white spot typically no spots, but in typically one white spot, typically one white typically no spots, but Fig. 7) spots, but in 21% one 31% one or two white but in 33% no spots spot, but in 10% no in 10% one spot

or no spots spots spots