Acisoma ascalaphoides Rambur, 1842

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 : 167

Acisoma ascalaphoides Rambur, 1842 —Littoral Pintail

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

Material. Madagascar: 3 male, Maroantsetra, Voloina, 30-xii-1971, P. & J. Minet ( MNHN); 2 males, Tolagnaro, Mandena, 12-ii-2004 / 19-iii-2004, K. Schütte ( RMNH); 4 males, Tolagnaro, Sainte Luce, Akaifira, 02-xii-2006, K. Schütte ( ZMUH); 1 male, Tolagnaro, Sainte Luce, S8, forest, marecage, 18-x-2006, K. Schütte ( ZMUH); 1 male, Tolagnaro, Sainte Luce, S9, marecage west, 01-iv-2004, P. Razafindraibe ( ZMUH); 2 males, Tolagnaro, Mandena, bridge from M15 to M16, 13-x-2006, K. Schütte ( ZMUH); 1 male, Tolagnaro, Mandena (Citronelle), 13-x-2006, K. Schütte ( ZMUH); 5 males, Tolagnaro, Mandena, 17-iii-2004 / 18-iii-2004 / 19-iii-2004 / 22-iii-2004 / 27-iii-2004, P. Razafindraibe ( ZMUH); 1 male, Tolagnaro, Mandena, marecage, 12-ii-2004, K. Schütte ( ZMUH).

Male diagnosis. Distinctive species confined to the east coast of Madagascar that appears somewhat intermediate between A. trifidum and the species formerly treated under A. panorpoides . Its unique characters are the (1) uniformly brown antefrons, clypeus, labrum and labium ( Fig. 4 F, 5H); (2) largely brown thorax with faint and limited paler markings ( Fig. 6 G); (3) mostly 2 cells in Fw triangle, although 37% of examined wings with 1 cell; (4) abdomen that narrows most on S5–6 while S7–10 are slender ( Fig. 7 E); (5) ventrally entirely dark abdomen with extensive dorsal white markings only on S3–6, which are solid and clean-cut but not confluent across dorsal carina ( Fig. 7 E); (6) narrow lobe of hamule with notched tip ( Fig. 8 E); and (7) black dorsum of cerci, not largely white ( Fig. 7 E). Similar only to A. trifidum are the (8) more numerous Fw Ax, usually 8½ but occasionally 8 or 9½.

Range and ecology. Known only from littoral forest fragments at the southern (Tolagnaro, formerly Fort Dauphin) and northern (Voloina) ends of Madagascar’s east coast ( Fig. 9 B). Only about 10% of the original cover of these forests remains, all in small patches of which only 13% are protected ( Consiglio et al. 2006). The species may occur elsewhere along the coast, but as it seems restricted to this habitat, could well be under threat ( Schütte & Razafindraibe 2007). The larvae are possibly adapted to more acidic water than A. attenboroughi sp. nov.

Figures

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 6. Thorax of Acisoma species in lateral view. A: A. variegatum, B: A. inflatum (typical), C: A. inflatum (dark), D: A. panorpoides, E: A. attenboroughi (typical), F: A. attenboroughi (dark), G: A. ascalaphoides, H: 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.