Pseudagrion perfuscatum Lieftinck, 1937

Seehausen, Malte, Kalkman, Vincent J. & Bedjanič, Matjaž, 2025, Revision of the Pseudagrion red-group occurring in Asia west of Lydekker’s line, with description of four new species (Odonata: Coenagrionidae), Zootaxa 5587 (1), pp. 1-66 : 35-37

Pseudagrion perfuscatum Lieftinck, 1937

Figures: 61–62 (holotype ♂, envelope); 91 (head ♂); 108 (pterothorax ♂); 125a, b (abdomen ♂); 142a–c (caudal appendages ♂); 163–164 (field photos ♂).

Pseudagrion perfuscatum : Lieftinck 1937: 94–97, Fig. 21 (description ♂ ♀; ♂ appendages; West Borneo [West Kalimantan, Indonesia]);— Orr (2001): 186 ( Brunei);— Malkmus (2005): 11 (Mount Kinabalu, Sabah);— Dow (2005): 10 ( Sarawak);— Dow et al. (2024): 37 (Kalimantan, Brunei, Sarawak, Sabah).

Pseudagrion pruinosum : Laidlaw (1915): 275 (Mt. Merinjak [ Sarawak, Malaysia]).

Examined specimens from the type series (1♂, 1♀)

♂ holotype, 5.–16.xi.1931, Singkawang, weg naar Bengkajang, West Borneo , L. Coomans de Ruiter leg., RMNH, JvT no. 2842 ( Figs 61–62) ;— 1♀ paratype, 5.–16.xi.1931, Singkawang, weg naar Bengkajang, West Borneo , L. Coomans de Ruiter leg., RMNH, JvT no. 2842 ( Figs 61–62) .

Other specimens examined (3♂♂)

Indonesia, Borneo Island: 1♂, 1.–7.i.1925, Lebang Hara, Sammelreise Prof Dr H. Winkler, ZMH ;— 2♂♂, 16.xi.1931, Singkawang, West Borneo , L.C. d.R. leg., RMNH , no. 1658921, 1658922.

Characterization of male

Head ( Fig. 91): Labrum, clypeus, antefrons, postfrons, and vertex orange in preserved specimens but red in living individuals; a black spot posterior of median ocellus, and black patches along lateral ocelli towards orange colour of occipital bar; postocular spots orange-red, separated by black from postfrons and vertex; rear of head black, but yellow along the eye margins, may be covered with bluish pruinosity; base and scape of antennae orange-ochre, following segments brownish.

Thorax ( Figs 61, 108):Anterior lobe of pronotum reddish, its margins washed-out blackish; middle pronotal lobe black, with a centrally divided red patch in the middle, and on each side a large red patch dorsolaterally; propleuron black above, pale orange below and to rear; posterior lobe of pronotum red, with its margins washed-out blackish; apical edge of posterior lobe convex. Pterothorax reddish-brown, with a black middorsal stripe; humeral suture at least with an elongate black patch at its posterior quarter, but may likewise be completely black; interpleural suture with a black line, a black spot may be present anteriorly; metapleural suture with a black streak situated at posterior quarter; venter pale; may be covered with bluish-white pruinosity up to interpleural suture. Legs pale orange; femora with black stripe outside; tibiae with black along spines; spines black.

Abdomen ( Figs 61, 125a, b): S1 red, with a blackish basal spot covering two-thirds of dorsum, segment may be completely covered with bluish-white pruinosity; S2 red, with black dorsally, may be completely covered with bluish-white pruinosity; S3–8 dorsally black, laterally pale yellowish; S9 red with its posterior third to half black; S10 black.

Caudal appendages ( Figs 142a–c): Cercus laterally blackish, but may be reddish at base; in lateral view cercus shorter than S10, the upper margin slightly convex, its apex almost square, inter-lobe notch barely or not apparent in this view; viewed dorsally the apical part of the superior lobe of the cercus curved inwards and runs as a ridge to the inter-lobe notch, with a separate inward directed projection proximal of this visible in dorsolateral view; another inwardly directed projection is situated more proximally at around the middle of the cercus; the inferior lobe of the cercus with a distinct ridge, best visible in dorsolateral view; a small bulge-like interior projection at the base of this ridge is visible in dorsal and dorsolateral view; paraproct pale orange, ventrally blackish; as long as two-thirds of the cercus; in lateral view subtriangular and tapered, with rounded apex; in dorsal view broadly rounded, concave bowl-like; blackish tubercular at medial edge.

Characterization of female ( Fig. 61)

Head: As in male but orange-brown instead of reddish; black colour on vertex reduced to patches proximal of each lateral ocellus; postocular spots surrounded by black.

Thorax: Pronotum as in the male, but brownish-ochre instead of reddish; horns of posterior pronotal lobe directed towards head, reaching the centre of the middle lobe. Pterothorax as in male, but yellowish-ochre instead of reddish; humeral suture with a thin black line, and an elongated black patch at posterior quarter; upper third of mesinfraepisternum black.

Abdomen: S1–2 dorsally black, laterally yellowish-ochre; S3–8 dorsally black, laterally yellowish; S9–10 dorsally black, lateral half yellowish-ochre. Cercus brownish; paraproct pale, in lateral view rounded; ovipositor pale yellowish-ochre, not reaching posterior margin of S10; two brownish styles reaching to beyond S10; inferior edge of ovipositor bearing several very small teeth.

Wings of both sexes with 11.5–14.0 px in forewing, and 10.5–13.0 px in hindwing.

Measurements of both sexes (mm): Total length (with appendages) 38.5–40.7; abdomen length (without appendages) 30.0–33.4; hindwing 19.0–23.0; forewing 22.0–23.8; Pt in forewing 0.8–0.9; male cercus 0.5.

Diagnosis

The males of P. perfuscatum have the clypeus and frons red ( Fig. 91), a character which separates this species from almost all congeners except for P. pilidorsum ( Figs 64, 92). The morphology of the male caudal appendages of P. perfuscatum and P. pilidorsum is almost identical ( Figs 142a–c, 143a–c). But at least in fully mature males the colour pattern separates both species: P. pilidorsum has less black on vertex and along the largely red postocular spots compared to P. perfuscatum ( Figs 91, 92). Additionally mature males of P. perfuscatum have the dorsum of S1–2 blackish and covered with pruinosity ( Figs 61, 125a, b, 163, 164), the lower half of the pterothorax is covered with pruinosity as well, and usually there is a black humeral stripe ( Figs 61, 108, 163, 164)—making the colour pattern almost unmistakable; whereas P. pilidorsum has the dorsum of S1–2 reddish ( Figs 126a, b, 165, 166), the pruinosity on them is restricted to venter, and at least slightly expanded laterally, the pruinosity on the pterothorax is restricted to the venter and metepimeron, and a humeral stripe is lacking ( Figs 63, 64, 109, 165, 166). [Note: See discussion section for further information].

Distribution

This species is endemic to Borneo, and recorded from Brunei, Indonesian Kalimantan, as well as from Malaysian Sarawak and possibly Sabah ( Fig. 1).