Acisoma inflatum Selys, 1889

Mens, Lotte P., Schütte, Kai, Stokvis, Frank R. & Dijkstra, Klaas-Douwe B., 2016, Six, not two, species of Acisoma pintail dragonfly (Odonata: Libellulidae), Zootaxa 4109 (2), pp. 153-172 : 159-162

Acisoma inflatum Selys, 1889 —Stout Pintail

( Figs. 4 B, 5B–F, 6B–C, 7B, 8B, 10B)

Material. D.R. Congo: 2 males, Orientale, Kisangani, Scolasticat, 07/ 10-vi-2010, K.-D.B. Dijkstra ( RMNH); 1 male, Equateur, Lower Itimbiri, Loeka river mouth, 11/ 16-v-2010, K.-D.B. Dijkstra ( RMNH); 1 male, Bangala, Mobeka, xii-1934, collector unknown ( RMNH);— Congo: 1 male, region de Kouilou, Pointe Noire, 03/ 04-iii-2010, P.H. Lambret ( RMNH).— Gambia: 1 male, West District, Abuko, 15-xii-1980, M. Hämäläinen ( RMNH).— Benin: 1 male, Department de l’Atlantique, So-Ava, 25-xii-2000, S.L. Tchibozo ( RMNH).— Ghana: 1 male, Central Region, 12 km NW of Cape Coast, river below Brimsu dam, 20-iv-2000, K.-D.B. Dijkstra ( RMNH).— Cameroon: 1 male, Centre Province, 55 km NW of Yaoundé, Sanaga River at Monatélé, 04-vi-2008, K.-D.B. Dijkstra ( RMNH).— Liberia: 1 male, Nimba County, Mt Tokadeh, 02-x-2010, K.-D.B. Dijkstra ( RMNH).— Gabon: 1 male, Haut-Ogooué, Mikouanga, Moanda, 01-vi-2009, N. Mézière ( RMNH).— Angola: 1 male, Uíge, 5 km of Negage, lake at Canuango source, 24-xi-2012, K.-D.B Dijkstra ( RMNH).— Uganda: 1 male, Lake Nabugabo, 1999, V. Clausnitzer ( RMNH); 1 male, Ddewe, vi-1949, E. Pinhey ( RMNH).— Kenya: 1 male, coast south of Mombasa, 28- x-1990, V. Clausnitzer ( RMNH).— Chad: 2 males, Chari-Baguirmi, N’Djaména, 02-viii-1992, H. Feijen ( RMNH).— Algeria: 1 male, Algiers, 1892, coll. Albarda ( RMNH).— Egypt: 4 males, Siwa oasis, 3 km of Siwa town, Fatnas spring, edge of Birket Siwa, 15-vi-2009, K.-D.B. Dijkstra ( RMNH); 1 male, Dakhla oasis, Rashda, 27-x-1977, S. Thomas ( RMNH).— South Africa: 1 male, KwaZulu-Natal, Himeville, Moorcroft Manor, 27-ii- 2014, K.-D.B. Dijkstra ( RMNH); 1 male, KwaZulu-Natal, 39 km W of Bergville, Royal Natal National Park, Mahai Dam, 02-iii-2014, K.-D.B. Dijkstra ( RMNH); 2 male, Mpumalanga, 20 km ESE of Badplaas (= Emanzana), Teespruit River N of Lochiel on R545, 27-iii-2014, K.-D.B. Dijkstra ( RMNH); 2 male, KwaZulu-Natal, 6 km NE of Manguzi, dam NW of Kosi Bay Lodge, 01-iv-2014, K.-D.B. Dijkstra ( RMNH); 1 male, KwaZulu-Natal, 15 km NE of Manguzi, Kosi Bay estuary, 03-iv-2014, K.-D.B. Dijkstra ( RMNH).

Male diagnosis. Typical of the group lumped formerly under A. panorpoides by the (a) extensively white labrum, labium, thorax and underside of S3–7; (b) low number of Fw Ax, usually 6½ or 7½, but sometimes 8½; (c) 1 cell in Fw triangle, but 2 cells in 11% of examined wings; (d) long Fw Pt, about 11–16% as long as Hw; (e) abdomen that narrows abruptly on S 5 in lateral view, with S6–10 slender ( Fig. 7 B); (f) fragmented and frayed white markings on S2–5 and large white lateral spots S7 ( Fig. 7 B); and (g) broad and triangular lobe of hamule ( Fig. 8 B). The only species with no known unique structural or coloration characters, although it is the smallest species on average, with Hw shorter than in any of the other species in about a third of the specimens ( Fig. 3 ). Being widespread in Africa, it must be separated with care from the more localised A. variegatum with which it shares the (1) relatively slender abdomen, with S6 usually over 2x as long as high, and ventral borders of S5 and S6 (almost) confluent; (2) sublateral black marking concentrated on the basal side of S4 ( Fig. 7 B); and (3) rather wide base of the hook of the hamule ( Fig. 8 B). Differs from that species by the (4) smaller size, with Hw 16–22 mm, although occasionally larger; (5) entirely black carinae forming the ventro-apical corner of S4; (6) all black lateral carina of S5; and (7) S6 at most 2.5x as long as high ( Fig. 7 B).

Range and ecology. Occurs throughout the geographic and habitat range (any calm grassy water body) formerly associated with A. panorpoides in continental Africa, including the relictual localities in northern Africa ( Fig. 9 A). Overlaps with A. variegatum in eastern and southern Africa (found at the same pond in coastal KwaZulu-Natal), but appears to be the only one of the pair in the more forested lowlands of western and central Africa.

Figures

FIGURE 3. Scatter plots of (proportions of) the lengths of S 5 and S 6 carinae and Hw in Acisoma species; filled diamonds: A. variegatum, open squares: A. inflatum, filled triangles: A. panorpoides, crosses: A. attenboroughi, stars: A. ascalaphoides, open circles: A. trifidum. The relationship of the proportion between the ventro-apical and lateral carinae of S 5 with the dorso-basal and dorsal carinae of S 5 is similar to that of the latter with the dorso-basal and dorsal carinae of S 6.

FIGURE 4. Head of Acisoma species in rostral view. A: A. variegatum, B: A. inflatum, C: A. panorpoides (typical), D: A. panorpoides (pale), E: A. attenboroughi, F: A. ascalaphoides, G: A. trifidum.

FIGURE 8. Secondary genitalia of Acisoma species in ventral view. A: A. variegatum, B: A. inflatum, C: A. panorpoides, D: A. attenboroughi, E: A. ascalaphoides, F: A. trifidum. Structure of hamule indicated.

FIGURE 9. Distribution of Afrotropical Acisoma species based on examined specimens and verified records in Odonata Database of Africa (see supplementary materials): A: A. inflatum (circles), A. attenboroughi (triangles), unverified records of A. inflatum or A. variegatum (grey dots); B: A. variegatum (circles), A. ascalaphoides (squares), A. trifidum (crosses), unverified records of A. inflatum or A. variegatum (grey dots). All records are provided in Suppl. Tab. 1 available from https: // science. naturalis. nl / dijkstra.

FIGURE 7. S 2 – 10 of Acisoma species in lateral view, scaled to their average size. Segment numbers and relevant characters are indicated.