Papuagrion chrysosoma Orr & Richards, 2016, sp. nov.

Papuagrion chrysosoma sp. nov.

(Figs 1 a,b; 2a,b; 3a; 4a; 5a,b,c; 6a,b; 7)

Material examined. Holotype ♂ (SAMA 07-001409), Papua New Guinea, Western Province, Tupnonbil area, Yakulgabip (5.1202°S, 141.2582°E; 1,817 m a.s.l.) 17.ii.2013, leg. S.J. Richards. Paratypes: 1 ♂ (SAMA 07- 001410), same data as holotype but 24.ii.2013; 1 ♀ (SAMA 07-001411) same data as holotype but 18.ii.2013.

Etymology. The specific epithet is a noun in apposition compounded from the Greek chrysos meaning gold and soma meaning body, in reference to the insect’s extensive golden yellow markings.

Description of holotype male. Head (Figs 1 a, b): Labium pale ochreous yellow with three small, obscure, dark markings at its base and darkish tips to the palps. Mandibles, labrum, and entire face to level of antennal sockets bright golden yellow, the same colour extending between the antennae as a rounded intrusion almost as far as the median ocellus and at the sides reaching narrowly along the eye margin from the genae to the level of the median ocellus. Remainder of head matt black except for a brownish orange patch centrally along the hind margin reaching forward to the posterior ocelli, with a fine finger-like projection extending between them. Eyes in life shining black.

Thorax (Figs 1 a, 2a): Prothorax with shallow dorsal profile except for raised anterior lobe; midlobe weakly convex; hindlobe depressed, in dorsal view with centre deeply excavated along posterior margin and lateral ear-like lobes somewhat elongated towards centre. Ground colour of prothorax deep orange-brown with blackish areas on most of dorsum of median lobe and all of posterior lobe. Synthorax black, brilliant chrome yellow dorsally and pale cerulean blue; dorsum with fine slightly metallic black, median line along median carina; remainder of mesepisternum deeply infuscated to the point of being black, lightening somewhat towards humeral suture; thin bright greenish yellow streak along suture; mesinfraepisternum black with thin yellow edging at sutures; mesepisternum and metepimeron black with broad, irregular, dorsal, yellow band extended finger-like down mesopleural suture and faintly connected to small green triangle ventrally on metepimeron, continuing to cover the anterior half of metainfraepisternum; metepimeron pale cerulean merging to yellowish dorsally; antealar triangles and all structures of intra alar sinus bright yellow; venter yellowish buff. Legs short with short, moderately dense spines; coxae dark with pale apical marking on middle and especially hind pair; trochanters mainly dark; femora and tibiae bright orange-brown with dark flecks at outer posterior bases of tibiae; spines dark; tarsi medium brown.

Wings (Fig. 3 a) moderately broad and slightly pointed apically; neuration typical for genus; Ac in forewing just beyond midpoint of Ax1 and Ax2; well beyond midpoint in hindwing; forewings Px 16, 16; hindwings Px 14, 14; Pt russet brown and about 1.5 times as long as broad; moderately skewed parallelogram; set well back from apex with row of six to seven crossveins between Pt and wingtip.

Abdomen long and fairly robust; S1, S2 tergites entirely bright yellow; remainder dark dorsally with wide yellow basal spot on S3, paired, very small lateral spots on S4–7; yellowish, thin, transverse apical bands on S7–9; laterally S3–10 with lower parts yellowish, the sinuous margin becoming thinner posteriorly so at S10 pale colour confined to venter; apical half of dorsum of S10 strongly raised to form a pyramid with faint pale marks along crest and posterior prominence. Appendages as shown in Figs 4 a, 5a,b,c. Upper branch of cercus in profile thin and strongly curved downwards, black; lower branch robust, about half length of upper, terminating in a thin sharp upwardly curved spine, basally brownish with tip dark. Paraproct in profile with very broad, short, yellowish base and long, thin, dark spine arising from upper third nearly reaching level of cercus tip; in ventral view paraprocts (Fig. 5 c) roughly triangular with a small inner shoulder. Anal plate, best seen in caudal view (Fig. 5 a), broad, divergent with two distinct arms, dark brown; in ventral view tips visible beyond margins of paraprocts. Measurements (mm): hindwing 26.5, abdomen + appendages 42.0.

Variation in male paratype. Slightly larger than holotype: Hindwing 28.5 mm, abdomen + appendages 44.5 mm; forewings Px 15, 15; hindwings Px 14, 15; yellow and orange markings on head slightly reduced; pale marking on ventral parts of abdominal S3–10 clearly reduced with venter of S9 besmirched; anal plate more clearly triangular, not incised along lateral margin and less so posteriorly than in holotype; paler in colour. Fig. 7 shows this individual in life.

Description of paratype female. Head: Labium marked as in male, ground colour slightly darker. Mandibles, labrum, and entire face marked as in male but yellow replaced by dark orange-tinged brown, with deep orange highlights at various sutures; paler area along eye margin from genae to level of median ocellus tending to greenish. Remainder of head matt black except for two well-separated, small, brownish orange spots on hind margin near inner corner of postoccipital lobes.

Thorax: Prothorax (Fig. 2 b) generally as in male but black marking less well defined and more extensive; posterior lobe in dorsal view with hind margin centrally excavated to about half its depth, the excavation including two short, median, finger-like processes separated by a deeper narrow excavation; lateral lobes only slightly produced inwards. Synthorax marked as in male with colours slightly less brilliant and dark areas blending less distinctly. Wings as in male; forewings Px 15, 15; hindwings Px 14, 14.

Abdomen long and robust; S1, S2 tergites entirely bright yellow as in male but some infuscation apically on S2; S3–10 marked as in male but pale colour less extensive than holotype; extensive drab orange marking on S8 and S9 and sides of valvae mainly straw-yellow edged with black. Cerci black, slightly longer than S10 along its dorsal margin; paraproct shallow, dark. Anal plate shaped as in male but smaller, smoothly incised along lateral margins but posterior margin only slightly concave (Fig. 6 a). Ovipositor well developed with very fine teeth along ventral margin; tip of valves surpassing hind margin of S10 and stylus extending beyond tip of cercus (Fig. 6 b).

Measurements (mm): hindwing 28.5, abdomen + appendages 40.2.

Diagnosis. A large, heavily built coenagrionid with relatively long abdomen and bright yellow markings on head, thorax and basal abdominal segments in the male and thorax and abdomen base in female, a condition unique in the genus. Anal appendages structurally significantly different from any known Papuagrion species but most easily recognised by the coloration in both sexes.

Habitat and behaviour All individuals of Papuagrion chrysosoma were found around the edge of a forest clearing adjacent to Yakulgabip hamlet near the base of the Hindenburg Wall. The forest at the type locality had been recently cleared for a garden that was located at the easternmost edge of an expansive patchwork of old and new gardens; the new garden represented a recent intrusion into an extensive area of lower montane rainforest that extended to the east of Yakulgabip. Individuals of this species perched on low vegetation at the forest edge in or near small patches of remnant rainforest. Pandanus plants were common within the forest, and P. chrysosoma was not observed more than 20 m away from the forest in the clearing. The climate at Yakulgabip was extremely wet, and flight was observed only during very brief periods of sunshine that totalled no more than 3–4 hours over several days of sampling. In flight the bright yellow markings of this beautiful species produce a ‘flash’ of yellow as they dart through low foliage in dappled sunlight. This species was not observed at lower altitudes (330–900 m a.s.l.) in the Ok Tedi catchment near Tabubil despite intensive surveys there.