Macrocnemis gracilis, Theischinger, G., Gassmann, D. & Richards, S. J., 2015

Theischinger, G., Gassmann, D. & Richards, S. J., 2015, Macrocnemis gracilis, a new genus and species of Idiocnemidinae (Zygoptera: Platycnemididae) from Papua New Guinea, Zootaxa 3990 (3), pp. 429-436 : 430-435

Macrocnemis gracilis sp. nov.

Figs 1–16

Holotype. ♂ ( SAMA 07-001406): Papua New Guinea, Hindenburg Range, Bilbilokabip (5.1203o S, 141.2512o E, 1770 m asl), 14-II-2013, S. J. Richards leg.

Paratypes. 3♂ ( SAMA 07-001407, RMNH, ZFMK ODO 20150001), same locality and collector, 12–17-II- 2013, 2♀ ( SAMA 07-001408, RMNH) same details as holotype, collected 12 and 22-II-2013, respectively.

Etymology. Gracilis (= Latin for slender) owing to the very long and slender abdomen of the male.

Description of the holotype male. Head. Labium with median incision U-shaped, largely yellow; mandibles basally pale green, otherwise brown to black; labrum dull pale green, basally very narrowly and in dorsal half along midline broadly black; anteclypeus black; genae, postclypeus and anterior frons up to antennal bases pale bluish green, a narrow black line separating postclypeus and frons; top of frons, pedicel, vertex and postocular lobes largely black, a spot each side of median ocellus and anterior to each lateral ocellus and a narrow occipital line pale brownish yellow; small postocular spots pale green; postgenae in preserved specimen largely dull yellow.

Thorax. Pronotum medially more or less broadly black, laterally yellow; posterior lobe upright, more or less rectangular with top corners drawn out into tongue-like lobes; episternum about half black and half yellow; epimeron largely black, yellow only along ventral margin. Synthorax black with wedge-shaped antehumeral patch, parts of dorsal half of mesepimeron and more than anterior half of metanepisternum, almost all of metepimeron and metapostepimeron, two anterior spots and posteroventral corner of mesokatepisternum and only posteroventral tip of metakatepisternum pale green to dull yellow; metapostcoxae and poststernum dull yellow; coxae and trochanters largely dull yellow, femora largely dull to greyish and brownish yellow lined with blackish grey, foretibia greyish black, meso- and metatibia with inner face greyish black, otherwise pale greyish to dark yellowish brown; all spines (6 doubles and 1 single on fore- and mesotibia, 7 doubles and 1 single on metatibia) and tarsi black; claws greyish to yellowish brown with small secondary tooth.

Wings. Membrane hyaline; venation blackish brown. Wing length:greatest width ratio 6.0–6.3; wing tips very weakly crenulated from 5 cells beyond pterostigma to R4 meeting wing margin; 16–17/14 postnodals; pterostigma about 1½ times as long as wide, parallelogram-shaped, greyish brown; overlying generally 1 cell. Other characters as given under Macrocnemis gen. nov.

Abdomen. Largely black with predominantly pale brownish yellow markings including in S1 approximately apical half and ventral margin, in S2 much of ventral margin; in each of S3–7 an ill-defined basal ventrolateral patch covering 1/6 or less and an even less well-defined ventrolateral patch covering more than subapical 1/6 of segment length, in S8 much of sides, in S9 apical half and in S10 almost all of it. S 2 in addition with a well-defined yellowish-green dorso-median patch over approximately medial third of its length. Anal appendages pale brownish yellow with cerci boomerang-shaped with dorsal bump beyond mid-length and bifid apex shaped similar to a boxing glove and paraprocts slightly longer than cerci, from wide and deep at base tapering into slightly curved/ sinuous slender rods ( Figs 8–10 ).

Ligula. Ligula in ventral view narrow, elongate ( Fig. 11 ). Terminal segment with apical lobes medium-sized, lanceolate ( Fig. 12 ), slightly twisted in posterior lateral view ( Fig. 14 ). Limbus membranosus short, covered with spine- or setae-like processes ( Fig. 13 ).

Measurements. Hw 30.0 mm; abdomen including anal appendages 46.2 mm.

Variability. All paratypes agree well with the description of the holotype. The range of the species’ postnodals is 16–17/13–14, of hindwing length 30.0– 32.9 mm, of abdomen length (including appendages) 46.2–49.0 mm.

Female. Head. Labium dirty to bright yellow, lateral (movable) hook black, end-hook yellow; mandibles dirtyyellow, distal parts brown to black; labrum obscure brown-black to olive-green, a weak light-brown marking to either side of the medio-basal oval black depression; anteclypeus dark brown; postclypeus dirty brown-black to yellowish-green; frons covered by a yellowish-green stripe, laterally extending up to eye margins, dorsally up to antennal scapi, at that level somewhat intermingled with black; antennae medium to dark brown; vertex and occiput dark greenish-brown to black, intermingled with rusty areas, the latter colour concentrated around and between ocelli; a diffuse dark spot attached to inner side of posterior ocellus, respectively; area between ocelli and occipital ridge conspicuously deep black, either entirely so or marked by a distinct black line. Rear and underside of head yellowish-white.

Thorax. Prothorax with both halves of median lobe distinctly bulgy in lateral view; posterior pronotal lobe not upright, a little more than half length of median lobe, simpler shaped than in male and smoothly rounded, with sublateral areas not protruded but slightly emarginate (almost trapezoid-shaped in dorsolateral view), lateral edges distinctly protruded but rounded. Colour of prothorax, legs and synthorax similar to male but generally paler and of less contrast. Synthorax with black markings less extensive than in male, that on upperside of synthorax restricted to cover dorsal carina. Underside of synthorax yellowish-white.

Wings. 15–16/13 postnodals; length:greatest width ratio 6.2.

Abdomen. Colour similar to male but S8 to 9 with weaker diffuse yellow-white markings, roughly covering lateral areas of posterior halves of segments and entire ventrolateral area of S8. S10 dark brown, laterally with a diffuse medium brown area at either side. Cerci, valvae and styli largely deep black, but upper part of valvae, visible part of ovipositor and distal fifths of styli light brown. Rear of abdomen bright yellow, framed by black.

Measurements. Hw 32.5 mm; abdomen including styli 44.5–45.5 mm.

Diagnosis. The largest species of idiocnemidine Platycnemididae from New Guinea (with wings at least 30 mm, abdomen almost 50 mm); three cells between quadrilateral and subnodus and distal margin slightly but distinctly crenulated in both wings; cerci and paraprocts of male subequal in length.

Habitat. The type locality, Bilbilokabip, is a small hamlet used by local landowners as a temporary shelter when hunting and gardening in the upper Kam Valley. The small clearing containing three huts is surrounded by extremely wet, moss-covered mid-montane rainforest where Macrocnemis gracilis perched on low vegetation overhanging or adjacent to small (1–2 m wide; Fig. 15 ) clear and heavily shaded streams. It was also encountered, but was less common, along a wider (5–10 m; Fig. 16 ) torrential stream that flooded regularly after heavy rain during the survey period. The streams where M. gracilis were encountered all had extensive canopy cover and dense riparian vegetation ( Figs 15, 16 ); the species was not encountered along streams where canopy cover had been opened during establishment of gardens despite extensive searches in more disturbed habitats.

Figures

FIGURE 1. Macrocnemis gracilis, male, in life, photo S. J. Richards.

FIGURES 2, 3. Macrocnemis gracilis, dry specimens: 2) male; 3) female; photos D. Gassmann.

FIGURES 4 – 10. Macrocnemis gracilis, male: 4) thorax, wing bases and abdomen, lateral; photo G. Theischinger; 5) prothorax, lateral; 6 – 7) posterior lobe of pronotum: 6) frontal; 7) dorsal; 8 – 10) terminalia: 8) dorsal; 9) ventral; 10) lateral.

FIGURES 11 – 14. Macrocnemis gracilis, ligula (penis): 11) ventral; 12) lateral; 13) ventrolateral; 14) posterolateral. photos D. Gassmann / K. Ulmen.

FIGURES 15, 16. Macrocnemis gracilis, habitats (at Bilbilokabip): 15) small stream; 16) large stream; photos S. J. Richards.