Anax tonga, Theischinger & Kalnins & Marinov, 2024

Theischinger, Günther, Kalnins, Martins & Marinov, Milen, 2024, Two new species of Anax Leach, 1815 from the Solomon Islands and Tonga (Odonata: Aeshnidae), Zootaxa 5519 (2), pp. 215-242 : 230-232

publication ID	https://doi.org/ 10.11646/zootaxa.5519.2.3
publication LSID	lsid:zoobank.org:pub:BE0CA3E4-3695-403A-AD98-3C279238518B
DOI	https://doi.org/10.5281/zenodo.13940295
persistent identifier	https://treatment.plazi.org/id/03C587C6-CE7B-987C-FF24-858F77A4F806
treatment provided by	Plazi
scientific name	Anax tonga
status	sp. nov.

Treatment

Anax tonga sp. nov.

( Figs 15 View FIGURE 13–17 , 18, 22 View FIGURES 18–25 , 34, 35, 48)

Holotype: ♂ (K.62615), Tonga, Jan 1930, H.R. Rabone leg. (in AM).

Etymology. The name refers to the type locality, the island of Tonga; tonga is used as a noun in apposition to the generic name.

Description of holotype

Head. Labium and bases of mandibles pale to dark brown; remainder of mandibles and genae black; labrum basally brown, merging ventrally into brownish black; anteclypeus, postclypeus and widely angulate (c. 160–170°) antefrons pale orange brown; top of frons with a brownish black thick-stemmed T-mark contrasting with the brownish yellow ground area, black at base of ‘T’ extending laterally and ventrally, transverse anterior bar of ‘T’ laterally not well defined; antennae, vertex, occipital triangle and what can be detected of postgenae black. Eyes dark brown.

Thorax. Prothorax largely brownish black and greyish brown. Pterothorax with pleura and antealar sinus pale orange brown without any distinct pattern recognizable. Terga largely yellowish brown to greyish brown. Sterna pale greyish brown. Legs: coxae, trochanters and base of femora brown, remainder of femora, tibiae, tarsi and claws black.

Wings. Humeral and axillary plates partly brownish black, partly yellowish grey. Venation greyish brown to black, costa with no median ray detectable. Membrane largely hyaline, Hw tinged very slightly pale brownish between anal loop and MA. Nodal index 12–22 / 22– 12 in Fw and 11–15 / 15– 12 in Hw; Ax1 and Ax8 thickened in both wings; wing triangles with 6 cells in Fw, 5 cells in Hw; Arc between level of Ax2 and Ax3; Pt 4.5–5.0 mm, dark greyish brown, overlying 2–3 cells; 7–8 double cells between MP and CuA of Hw; anal loop with 11–13 cells; 4 rows of cells between dark greyish brown membranule and anal loop.

Abdomen. Dorsally largely black, ventrally in different shades of brown. S3 Index c. 5.0. S1 blackish brown; S2 with orange basal ring (presumed green in life) covering approximately 1/6 of segment length, its median 1/5 produced backward in a small distinct semicircle; remainder with small ill-defined yellow patches (presumed blue in life) each side of large black strongly pimpled median area; S3 black with short pale orange basal mid-dorsal patch and pair of barely detectable brownish latero-basal smudges and pair of subapical dorsolateral dull yellow spots; S4–9 black, laterally with only few barely detectable brownish smudges and with only pair of dull yellow subapical dorso-lateral spots each; S9 and S10 appearing unmarked, black.

Terminalia. Cerci brown to black, with stalk moderately thick, short, slightly incurved; at least basal 2/3 of the remainder maximally almost twice as wide as in-curved tapered apical 1/3, the narrowing rather abruptly; apico-lateral spike also slightly in-curved and tiny, wide-based basal, inferior tooth. Epiproct largely brown, lateral edges black; basally markedly wider than long but barely 1/4 the length of cerci, apex very widely and shallowly emarginate; two pairs of small dorsal tubercles.

Measurements (in mm). Abdomen (including cerci) 63.1, cerci 6.3, Hw 53.5.

Female. Unknown.

Diagnosis. A large dark rather short-bodied Anax (body length c. 85 mm, wingspan c. 110 mm) with dark brown to black T-mark (top bar ill-defined) on largely yellow top of frons and with high S3 Index (male c. 5.0). Mature male, preserved ( Fig. 48 View FIGURES 48–49. 48 ) with head and thorax mostly pale orange brown (expected to be green in life), abdomen base pale orange brown and black, remainder of abdomen largely black. Abdominal pattern generally made up by pairs of very small ill-defined dull pale yellow subapical dorso-lateral patches each on at least S3–8 or 9, none on S1, S2 and S10 and possibly S9. According to specifications for Papuan Anax species by Orr & Kalkman (2015) A. tonga is a shorter-bodied species (Abd 63 mm, Hw 54 mm; ratio <1.3). With its long narrow waist the male appears most similar to A. celebensis , A. insulanus and A. piraticus . It can be distinguished from all of them by the apical 1/4 to 1/3 of the cerci noticeably arched inward and its tiny apico-lateral spike vs apical 1/3 of the cerci straight and with its apico-lateral spike larger and not in-curved. It can also be separated from A. celebensis and A. piraticus by its very dark abdomen with only a few barely detectable pale smudges and a pair of very small whitish yellow spots on at least S3–8 or 9 vs abdomen with much richer and larger pale patching. It can also be distinguished from the male of A. insulanus sp. nov., the most similar species, by the presence in the male of a pair of dull whitish yellow subapical dorso-lateral spots in S3 and possibly S4, by a markedly wider abdomen (approximately 4.2 mm wide vs 3.85 mm wide at S9, and an S3 Index of 5 versus 6.25) and by an abruptly vs continuously narrowed apical third of the cerci.

Distribution. Known only from Tonga, where it and a female of A. guttatus ( Fig. 49 View FIGURES 48–49. 48 ) from Tonga, Tubau College, Nafualu, Tongatapu, Jan 1930, H.R. Rabone leg. (in AM: K.62616) were collected. Possibly endemic to Tonga.