Anax Leach 1815
Creators: name: Theischinger, Günther
name: Kalnins, Martins
name: Marinov, Milen
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Odonata
Aeshnidae
Anax

description: Key for species identification (males only) of Anax from the Australian, the Oceanian and the south of the Indomalayan Biogeographical Realms
As characters such as e. g. ‘presence or absence and shape and definition of the postfrontal T-mark’, ‘colour of occipital triangle and vertex’ and ‘abdominal colour pattern’ have been found by other authors and ourselves as too variable to be used for specific distinction of Anax species, the key is primarily based on the shape and proportions of the elements of the male terminalia (epiproct, cerci) that appear in a high degree consistent and thus to be most useful for the identification of taxa of the species group. An illustration of the abdominal patterns (Fig. 53) that may also be useful is presented subsequent to the Key as a further aid to identification. However, it is important to point out inconsistencies and shortcomings in hitherto available keys or similar more or less comprehensive work. These are part of Martin (1909), Kennedy (1934), Lieftinck (1942), Michalski (2012), Orr & Kalkman (2015) and Seehausen (2017). Martin (1909) presents useful dorsal and lateral view illustrations of the male terminalia of A. strenuus, A. georgius, A. guttatus, A. gibbosulus, A. maclachlani, A. selysi and A. papuensis. He mentions A. panybeus only as a race of A. guttatus and does not refer to A. fumosus at all. Kennedy (1934) includes dorsal and lateral illustrations of the terminalia of A. piraticus, A. panybeus, A. gibbosulus, A. guttatus, A. strenuus, A. selysi and A. maclachlani. However, what he presents as A. gibbosulus is misleading, because it is probably only a different version of what he presents correctly as A. guttatus, and certainly not A. gibbosulus. Lieftinck (1942) presents excellent drawings of the available species including A. fumosus, but except A. georgius and A. papuensis. He adds two taxa of the species group he describes as A. pugnax and A. fumosus celebense. Michalski (2012) uses the illustrations of Martin (1909) and Lieftinck (1942) for the presentation of the species of New Guinea, Maluku and the Solomon Islands. Orr & Kalkman (2015) give excellent colour illustrations including dorsal view terminalia illustrations of New Guinea species, (but in the detailed line drawings of appendages A. fumosus and A. guttatus are mistakenly interchanged). Finally Seehausen (2017) when illustrating A. papuensis, A. guttatus, A. georgius, A. gibbosulus and A. panybeus depicts A. guttatus matching very closely the drawing A. f. fumosus of Lieftinck (1942) and A. guttatus (but actually A. fumosus) of Orr & Kalkman (2015). Seehausen’s drawing of the terminalia of A. panybeus looks almost like a copy of Lieftinck’s illustration of A. f. celebense and not at all similar to Lieftinck’s illustration of A. panybeus that matches the illustration of the type of this species by F.M. Carpenter in Kennedy (1934), as well as a photo of this species by Yen Choong Chee and Hagen material of this species in Vienna. This raises doubt as to whether the abdomens figured by Seehausen (2017) as A. panybeus (Fig. 21 j–l), and in particular if the thick-waisted females (Fig. 22 j–k), really are A. panybeus.
Key (Figs 52, 53)
1 Epiproct dorsally spiny and apically not emarginate (a) A. papuensis
- Epiproct not spiny and apically slightly to distinctly emarginate (b–p) 2
2 (1) Epiproct much longer than one half of cerci, more than twice as long as wide, apically distinctly A. georgius emarginate (b)
- Epiproct markedly shorter than one half of cerci, not much longer than wide, apically slightly 3 emarginate (c–p)
3 (2) Cerci distinctly increasing in width to markedly less than 1/2 their length; apically simply A. rounded without apico-lateral spike (c) maclachlani
- Cerci distinctly increasing in width to at least 1/2 their length; with apico-lateral spike of 4 variable size and form (d–p)
4 (3) Cerci widening from base to more than 3/4 length, thence abruptly narrowed (d) A. strenuus
- Cerci widening from base to maximally 2/3 length, thence parallel sided or more or less 5 continuously narrowed (e–p)
5 (4) Inner edge of cerci straight beyond midlength; ventral edge of cerci without prominent basal A. pugnax inferior tooth (e–f)
- Inner edge of cerci with some basal convexity or concavity; ventral edge of cerci with prominent 6 basal inferior tooth (g–p)
6 (5) Inner edge of cerci widely convex without basal concavity (h) A. gibbosulus
- Inner edge of cerci undulate with basal concavity before larger convexity (i–p) 7
7 (6) Cerci approximately three times as long as their greatest width, and apical 1/3 to 1/2 tapered 8 (i–j)
- Cerci approximately three times as long as their greatest width and apical 1/4 parallel sided (m), 9 or cerci approximately four times as long as their greatest width (k–l, n–p)
8 (7) Cerci greatest width at about 2/3 length and outer margin straight (i) A. piraticus
- Cerci greatest width at about 1/2 length and outer margin convex (j) A. selysi
9 (7) Cerci with apical 1/4 to 1/3 only slightly tapered and apically distinctly wider than at base, 10 giving them a truncate appearance (k–m)
- Cerci with apical 1/3 more distinctly tapered and apically barely wider than at base, giving them 12 a subtruncate to pointed (n) or rounded (o, p) appearance
10 (9) Cerci inner margin with middle portion not distinctly bulging (k) A. panybeus
- Cerci inner margin with middle portion distinctly bulging (l–m) 11
11 (10) Cerci with middle bulge not set off from slightly tapered apical 1/4 (l) A. fumosus
- Cerci with middle bulge set off from parallel sided apical 1/4 (m) A. celebensis
12 (9) Cerci with small apico-lateral spike pointing caudo-laterad, making them appear pointed (n) A. guttatus
- Cerci with tiny apico-lateral spike pointing straight backward or slightly incurved, making them 13 appear rounded (o–p)
13 (12) Cerci inner margin with middle portion not distinctly bulging (o) A. insulanus
- Cerci inner margin with middle portion distinctly bulging (p) A. tonga
Abdominal pattern (Figs 54, 55) of the Anax species (males) keyed
Unfortunately it was not possible to present all species in colour, but Figure 54 illustrated the dorsal view of the abdomen of all species, with colours where shown, as known or presumed to occur in life. Because of the small scale and the minute pale pattern elements (barely detectable in preserved specimens) in Fig. 54 the newly described species A. insulanus and A. tonga are also illustrated enlarged as known (A. insulanus) or presumed (A. tonga) in life, along with enlarged photos of critical characters S2–3 and terminalia (Fig. 55).
description: Published as part of Theischinger, Günther, Kalnins, Martins & Marinov, Milen, 2024, Two new species of Anax Leach, 1815 from the Solomon Islands and Tonga (Odonata: Aeshnidae), pp. 215-242 in Zootaxa 5519 (2) on pages 240-241, DOI: 10.11646/zootaxa.5519.2.3, http://zenodo.org/record/13915771