Drepanosticta machadoi, Theischinger, G. & Richards, S. J., 2014

Theischinger, G. & Richards, S. J., 2014, Drepanosticta machadoi spec. nov. from New Guinea (Odonata: Platystictidae), Zootaxa 3866 (1), pp. 145-150 : 146-148

Drepanosticta machadoi sp. nov.

( Figs 1–7 )

Material. Holotype ♂ ( SAMA 07-000988): Papua New Guinea, Western Province, Hindenburg Range, Dablin Creek (5.2156°S, 141.2309°E; 859 m asl), 2 March 2013, S.J. Richards ( SAMA).

Etymology. The species is named for the remarkable Brazilian odonatologist A.B.M. Machado on the occasion of his 80th birthday.

Diagnosis. A predominantly black damselfly, male with four pale/bright pattern elements on each side of synthorax. Fork of posterior lobe of pronotum (pronotal fork) wide-angled, with rather straight, narrow, fingershaped prongs. Mesepisternal and metepisternal patches shorter than, and mesepimeral patch longer than, in its congeners. Abdomen with ill-defined narrow basal rings in segments 2–8 and with dorsum of segments 9 and 10 largely bright blue.

Male. Labium grey to blackish brown and black; base of mandibles bluish white, remainder dark brown to black; slightly less than anterior half of labrum and all of postclypeus black, slightly more than posterior half of labrum and all of anteclypeus bluish white; genae and a bar from eye to eye between approximately postclypeus and level of antennal bases brown; remainder of frons and top of head dark brown to largely black; some yellowish grey between antennal base and eye margin; antennae with scape and pedicel greyish brown and flagellum black; postgenae largely yellowish grey to greyish brown, rather narrowly black along eye margins.

Pronotum ( Figs 2, 3 ) dorsally largely blackish brown, sides pale yellow, propleura black; posterior lobe of pronotum produced into a wide-based, wide-angled fork with finger-like prongs, base laterally without distinct corners.

Synthorax ( Fig. 7 ). Pleura largely brownish to shiny black with four pale greenish yellow patches: one, dorsally and medially ill-defined, in lateroventral 1/4 of mesanepisternum; one, very narrow and curved, in anterodorsal corner of mesepimeron; one along almost all of intersegmental suture in metepisternum; one, subtriangular, in anterodorsal corner of metepimeron. Poststernum yellowish brown to black.

Coxae greyish brown to black; trochanters yellowish to greyish brown; femora and tibiae yellowish to pale greyish brown with apex black, remainder of legs dark greyish brown; claws yellowish brown.

Wings with venation black and membrane hyaline; postnodals 19–20/18; pterostigma ( Fig. 4 ) black, narrowly whitish along bordering veins, particularly proximal and distal ones, approximately 1.8 times as long as wide, overlying 1–2 veins, posterior border distinctly longer than anterior border, proximal and distal borders subequal in length, proximal angle at R approximately 50º.

Abdomen ( Fig. 1 ). Segments 1–8 dark greyish brown to black, segments 2–8 with ill-defined narrow brownish yellow basal ring broken widely dorsally by blackish brown in segment 8; intersegmental membrane between segments 8 and 9 and a small medial patch at distal edge of segment 8 dorsally sky-blue; segment 9 dorsally bright sky-blue, ventrally black; segment 10 dorsally blue except for black posterior margin, ventrally black. Sternites generally greyish yellow to yellowish grey, sternite 9 yellowish grey to blackish brown. Anal appendages ( Figs 5, 6 ) black, superiors moderately thick, apically indistinctly double-hooked, inferiors at least as long as superiors, conical, ending very thin and single-hooked.

Measurements. Hindwing 24.6 mm, abdomen (including appendages) 32.0 mm.

Comparison with other species. Drepanosticta machadoi differs from all congeners except members of the D. conica group of Theischinger & Richards (2014) by having a black synthorax with a distinct pale/bright pattern that includes at least one element each on the mesanepisternum, metanepisternum and metepimeron and, in the male, terminal abdominal segments generally largely blue dorsally with simple stout superior and long, thin, hooked inferior anal appendages. The new species differs from members of the D. conica group ( D. conica , D. dorcadion , D. lepyricollis , D. taurulus , D. elaphos and D. pterophora ) in the unique structure of the posterior lobe of the pronotum, which is a wide-angled fork with rather straight, narrow finger-like prongs ( Figs 2, 3 , 14 ) versus subrectangular in D. conica ( Fig. 17 ), produced into a thin wing-shaped laterad directed flap on each side in D. pterophora ( Fig. 18 ), medially widely excised between long, mediad bowed, rounded lateral lobes in D. dorcadion ( Fig. 16 ), between short, mediad bowed, pointed lateral lobes in D. lepyricollis ( Fig. 20 ), between laterad curved, pointed lobes in D. taurulus ( Fig. 19 ), or a medially narrowly excised fork of pointed or multi-pointed prongs in D. elaphos ( Fig. 15 ). It also differs from D. dorcadion and D. elaphos by having four pale/bright pattern elements on the synthorax vs only three such elements, and from all other members of the D. conica group in the specific shape of these patches. In the new species they are short and square in mesepisternum, of about the same length, narrow and curved in mesepimeron, short and of similar width throughout in metepisternum and subtriangular in metepimeron ( Fig. 7 ) versus longer and subtriangular or subrectangular in mesepisternum, shorter and straight in mesepimeron, longer and of different width in dorsal and ventral section or evenly tapered or subdorsally strongly constricted/broken in metepisternum, and subtriangular to rhomboidal in metepimeron in the other members of the group ( Figs 8–13 ; summarized in key below).

Female. Unknown.

Distribution and habitat. The holotype was perched on low vegetation (~1.5 m above the ground) in deep shade, about 20 cm from a small (<50 cm wide, ~1.5 m drop) vertical waterfall in disturbed foothill rainforest ( Figure 1 ). The waterfall formed part of a small tributary, or side channel, of Dablin Creek, a steep and rocky stream draining the southern slopes of the Hindenburg Range at 859 m a.s.l. in the upper Ok Tedi headwaters of Western Province, Papua New Guinea. Despite intensively searching for several hours in the vicinity of the type locality no additional specimens were seen.

Figures

FIGURES 1 – 6. Drepanosticta machadoi, male: 1 lateral, photo by S. J. Richards; 2, 3 prothorax: 2 lateral; 3 posterior lobe, dorso-frontal; 4 pterostigma of forewing; 5, 6 anal appendages: 5 dorsal; 6 lateral.

FIGURES 7 – 13. Male thorax of Drepanosticta species: 7 D. machadoi, lateral; 8 D. elaphos, lateral; 9 D. dorcadion, only synthorax, frontal, lateral and ventral; 10 D. conica, only synthorax, frontal and lateral; 11 D. pterophora, lateral; 12 D. taurulus, lateral; 13 D. lepyricollis, only synthorax, frontal, lateral and ventral. Figs 9, 10, and 13 modified from Lieftinck (1938, 1949).

FIGURES 14 – 20. Male posterior lobe of pronotum (pronotal fork), dorsal, of Drepanosticta species: 14 D. machadoi, 15 D. elaphos; 16 D. dorcadion; 17 D. conica; 18 D. pterophora; 19 D. taurulus; 20 D. lepyricollis. Figs 15 and 18 modified from Theischinger & Richards (2014), Figs 16 and 20 from Lieftinck (1949), Fig. 17 from Lieftinck (1938), Fig. 19 from Theischinger & Richards (2005).