Aeschnosoma Selys Longchamps
Creators: name: Fleck, Günther
name: Mézière, Nicolas
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Odonata
Corduliidae
Aeschnosoma

description: Differential diagnosis, and a key to males of auripennis-group of species
The new species belongs to the genus Aeschnosoma according to the following diagnosis (which allows separation of the genus from all other New World genera of Corduliidae s.l.): 1) vertex bilobed, 2) all discoidal triangles and hypertriangles crossed, 3) FW subtriangle crossed, 4) FW discoidal field greatly widened distally (at the level of RP1/2 – RP3/4 fork), 5) FW subdiscoidal space with two or more crossveins (including CuP-crossing), 6) anal loop well developed, foot-shaped with distinct sole and midrib).
Fleck (2012) defined different species groups of Aeschnosoma; together with A. auripennis and A. heliophila, A. yelenae belongs to the auripennis -group (diagonosis of this group included in the key below). The presented key separates males of this group from congeners (female and larva of A. yelenae unknown):
1 clypeus, frons and side of thorax brown and lacking distinct and contrasting yellow markings; abdomen brown to dark brown and lacking yellow markings; proportionally very long legs (hind leg length ca 60% of HW length); similar unusual and unique posterior hamule [clearly bipartite with notably, in lateral view, 1) a well-developed inner lobe with apex bent backwards, 2) a distinctive outer lobe bearing a strong anterior spur and a moderately developed posterior hump, and 3) a posterior tuft of very long and strong setae] (cf text above, Figs 5, 11, and Neiss et al. 2013); similarly derived and curious vesica spermalis [with enormously developed V 1; small and straight V 2; elongated V 3, more than twice as long as wide; V 4 slightly shorter and lacking distinct flagellum and with well developed translucent membrane] (cf text above, Figs 6–8, 12, and Neiss et al. 2013); anal appendages of similar structure with cerci slightly divergent and straight in their proximal part and strongly bent inwards and somewhat downturned in their distal part, lacking indentation, distally flattened with dorsal membrane and distoventral tuft of strong setae (Figs. 9–10, 13–14)....................................................... auripennis -group (2)
1’ not as above...........................................................................other Aeschnosoma
2 in dorsal view distal part of cercus distinctly bent at obtuse angle (Fig. 13).............................. A. auripennis
2’ in dorsal view distal part of cercus distinctly bent at right angle (Figs 9, 14)....................................... 3
3 distal half of abdomen, including basal fourth of cerci, brown to orangish brown; epiproct mostly yellowish (except apex dark brown) (Fig. 14); in dorsal view, distal bend of cercus occupying about 3/10 of length (Fig. 14); in dorsal view; cercus with apex slightly but distinctly recurved (cerci J-shaped, Fig. 14).............................................. A. heliophila
3’ distal half of abdomen, including proximal part of cerci, dark brown; epiproct dark brown (Figs 9–10); in dorsal view, distal bend of cercus occupying about 2/10 of length (Fig. 10); in dorsal view, cerci with apex not recurved (cerci hockey club-shaped, Fig. 10)............................................................................... A. yelenae sp. nov.
Aeschnosoma yelenae can be easily separated from its close relatives by the shape of its cerci. This species also exhibits more pronounced melanism, S10 and the epiproct are dark brown whereas S10 is orangish brown and the basal third of the epiproct distinctly yellowish in A. heliophila and A. auripennis. The posterior hamule of the three species differs (compare Fig. 5 with Fig. 11 and Fig. 4 in Neiss et al. 2013): in A. yelenae the anterior margin of the inner lobe is distinctly arched and easily visible in lateral view whereas it is distinctly less arched and slightly angled, and also less visible (basal part mostly hidden by outer lobe) in A. auripennis and A. heliophila; its apex is rather narrow and rounded whereas it is distinctly larger and subrectangular in A. heliophila in lateral view; the free visible posterior part of the inner lobe is directed distinctly caudad at the base in A. yelenae whereas it is roughly perpendicular to the body axis in A. auripennis; in A. yelenae the anterior spur and the posterior hump of the outer lobe are less developed than those of A. heliophila, moreover the margin between these two structures is straight, whereas it is strongly concave in A. heliophila; the anterior spur of A. yelenae is longer and less curved than that of A. auripennis and posterior margin of the outer lobe is also less curved in the former. V 4 of vesica spermalis has a small apical lateral flap in A. yelenae, this flap is apparently absent or very poorly marked in A. heliophila (character state unknown in the unique A. auripennis studied, a dry-stored specimen not allowing clear view of membrane fine structure).
By virtue of their general appearance and the presence of cerci unusually bent at right angles (possible synapomorphy), A. heliophila and A. auripennis are for the present considered sister taxa.
description: Published as part of Fleck, Günther & Mézière, Nicolas, 2024, Aeschnosoma yelenae sp. nov. from French Guiana (Odonata: Corduliidae), with notes on its phylogenetic affinities and bionomics, pp. 443-450 in Zootaxa 5555 (3) on page 448, DOI: 10.11646/zootaxa.5555.3.7, http://zenodo.org/record/14594832