Indolestes obiri * Watson sp. n., 1979

J. A. L. Watson & M. S. Moulds, 1979, New Species of Australian Lestidae (Odonata), Australian Journal of Entomology 18, pp. 143-155 : 152-154

Indolestes obiri * Watson sp. n. (Figs 3, 4, 11, 34-37)

Indolestes sp. “o ” ; Watson, 1974: 142.

Types— Holotype ♂, Northern Territory: 12°23'S 132 ° 56'E, Cannon Hill, 7 km NW by N o f Cahill’s Crossing, East Alligator River , 27-28.v. 1973, J. A. L. W atson ( ANIC Type No. 9877) (in ANIC). Paratypes: Northern Territory: one ♀, 11 °59 'S 133 °05 ' E, 5 km S by W of Tor Rock , 5.vi. 1973, T. Weir ; one ♀, 12°16 'S 133°13 'E, Birraduk Crfeek, 18 km E by N of Oenpelli , 4.vi. l973, T. Weir ; one ♀, 12°18 ' S 133°17 'E, 15 km SW by S of Nimbuwah Rock , 10-ll. xi.1972, J. A. L. Watson ; one ♂, one ♀, 12°22 ' S 133°01 'E, 6 km SW by S of Oenpelli, 6.vi. 1973, T. Weir and A. Allwood ; three ♂♂, three ♀♀, same locality as holotype, 12-13.xi.1972, J. A. L. Watson ; six ♂♂, four ♀♀, same data as holotype ; one ♀. same locality as holotype, 27. V.1973, T. Weir and N. Forrester ; one ♂, 12°25 'S 132°57 ' E, Oberie (= Obiri) Rock, 2 km N N W of Cahill’s Crossing , East Alligator River , 29-30.v. 1973, J. A. L. Watson ; one ♂, 12°50 ' S 132 °52 ' E, Baroalba Gorge, 19 km E by N of M t Cahill , 8.iii. 1973, J. A. L. W atson ; one ♂, 12°52' S 132 ° 47'E, Nourlangie Creek , 8 km E of Mt Cahill, 17-18.xi.1972, J. A. L. W atson ; four ♂♂, one ♀, 12°52 ' S 132 ° 50' E, Koongarra , 15 km E of Mt Cahill, 24-25. V. 1973, J. A. L. Watson ; four ♂♂, 12°55' S 132°56' E, Lightning Dreaming Gorge , 25 km E by S of Mt Cahill, 12. vi.1973, T. Weir .

One paralectotype ♀ of Austrolestes albicauda tindalei , from Groote Eylandt , N. B. Tindale ( SAM), appears to be a very pale specimen of I. obiri . However, it is not to be regarded as a paratype of I. obiri .

Male

A sombre-coloured species, with pale brown and dull metallic green head and thorax, dark brown and cream abdomen.

* obiri, for Obiri (Oberie) Rock, a habitat of this cave-haunting lestid; to be treated as an indeclinable noun.

Head.—Labium yellowish; labrum and anteclypeus pale greenish brown, slightly darkened on either side of midline; mandibles and genae pale greenish brown; postclypeus pale brown, slightly and variably darkened, approximately central spot on each side; frons pale brown in front, dark greenish on top with pale middorsal stripe, forming pale T-shaped mark and upper part of anterior frons, sometimes obscured; vertex dark greenish, with pale brown ring around median ocellus, sometimes obscured, pale brown crescents beside and behind each lateral ocellus, meeting in midline, and pale spot behind each antenna; occiput pale brownish in midline, along postocellar suture, and occipital margin, leaving broad, irregular triangular green spot adjacent to eye; back o f head pale brown, except for dark green upper parts of postgenae, bordering eyes; scape dark brown, pedicel dark brown in front, pale brown behind, basal segment of flagellum pale brown, darkened apically, rest o f flagellum black.

Prothorax pale brown; median and posterior lobes with variable, dark green spots on either side of broad middorsal pale stripe; upper episternum and epimeron marked dark brown; coxa and trochanter pale yellowish brown, spinose inner surfaces of femur and tibia tinged dark brown; tarsi shaded dark brown.

Synthorax (Fig. 3) pale brown, m arked darker as follows; collar dark brown; a dark line on each side of dorsal carina, sometimes fused with greenish band extending across mesanepisternum from collar to dark antealar ridge and sinus, which is extended towards mesopleural suture near its centre, and over its upper quarter; a shadowing along mesopleural suture from large upper dark spot to dark spot at angle of suture; a diagonal, trilobed dark green band across mesepimeron, from mesopleural suture to upper middle lateral suture; dark stripe below subalar ridge continuing into triangular patch on metanepisternum, prolonged into dark brown line reaching almost to lower end of upper metapleural suture; a variable dark brown line along upper posterior corner o f metepimeron, adjacent to poststernum; black spot on either side of poststernum; sterna apparently dark brown and yellowish brown, a dark brown midventral stripe extending across metapostcoxales.

Coxae and trochanters yellowish; femora and tibiae pale brown, lined dark brown between rows of spines; tarsi pale brown, darkened distally, claws blackish.

Wings.—Average length of hind wing 22.34 mm (range 21.1-23.1 mm, N = 10); hyaline, most veins dark brown, R + M and R 1pale brown; pterostigma pale brown, that of fore wing averaging 1.368 mm long (range 1.28-1.40 mm), 0.566 mm wide (range 0.54-0.62 mm) (N = 10).

Abdomen (Fig. 11).—Tergite 1 pale brown, darker at extreme base and over distal third, posterior transverse carina dark brown; tergite 2 mainly dark brown above, with pale basal band continuing into pale lateral margin, broken middorsally by narrow dark line on either side of light middorsal stripe, and with illdefined pale transverse band approximately two-thirds o fsegment from base, connecting pale lateral areas at narrowest point of brown dorsal mark to dilatation of middorsal stripe; tergites 3-6 dark brown marked creamy white, the pale m arks increasingly obscured in the more posterior segments—a whitish basal band, broken above by fine dark line on each side of middorsal pale line, and broad whitish transverse band, expanded below, shading from brown approximately two-thirds of segment length from base in middorsal line, ending abruptly at dark brown band occupying distal 20% o f tergite; tergite 7 similar in pattern to tergites 3-6, the pale areas variably obscured, sometimes only basal band and lateral whitish patch evident; tergite 8 dark brown, with or without pale lateral spot just basal to midpoint o f segment; tergite 9 dark brown; segment 10 whitish, with dark brown posterior margin and variable basal dark brown band sometimes expanded at sides (Fig. 11), more commonly narrow, broadest middorsally.

Sternite 1 very pale brown; secondary genitalia pale and dark brown; sternites 3-7 with colour patterns matching those of corresponding tergites; sternite 8 dark brown, with pale patch on each side in distal half; sternite 9 pale brown.

Anal appendages (Figs 34-37).—Superior appendages averaging 1.350 mm long (range 1.30-1.42 mm, N = 10); basal quarter to third pale, apices dark brown; armature almost concealed in dorsal view, comprising ventral, backwardly curved spine bearing apical pencil of setae, and connected by low ridge to slim medioventral spine, the tip o fformer 0.67-0.75 x, o flatter0.34-0.39 x appendage length from base. Interior appendages rounded, pale brown, margined darker brown.

Female

Size as in male, hind wing averaging 22.49 mm long (range 21.6-23.2 mm), fore wing pterostigma 1.370 mm (range 1.30-1.42 mm) x 0.584 mm (range 0.54-0.62 mm) (N = 9), the abdomen stockier and shorter than in male, segments 8-9 swollen. Colour and pattern as in male, but dark markings, particularly of synthorax, less extensive (Fig. 4), and in female from G roote Eylandt much less extensive and paler, as in I. alleni ; middorsal pale stripe on tergite 3 ofalmost uniform width, not distended into pale spot; whitish bands on tergites 3-6 less well defined than in male, the subapical band narrower; tergites 8- 9 sometimes showing dark middorsal line and apical band, the adjacent areas slightly paler brown, the lateral parts of tergite pale brown.

Habitat

All but one of the known specimens of I. obiri were taken along the Arnhem Land escarpment and its outliers, where the damselflies frequent shallow caves and overhangs. The breeding grounds are unknown, although a male was taken, apparently on territory, over the upper floodwaters of Baroalba Creek in March 1973.