Orectognathus phyllobates

Brown (1957) - The discovery of phyllobates on foliage well above the ground, and Wilson’s observations on Orectognathus sarasini climbing treetrunks at night, tend to show that Orectognathus may be more or less generally a nocturnal, arboreal or subarboreal forager. That Orectognathus clarki Brown may have similar habits seems likely, in view of the fact that this species is never seen foraging outside the nest during the daytime (so far as limited observations go).

Identification
Brown (1957) - O. phyllobates is most closely related to Orectognathus nigriventris, but is easily distinguished by means of its broader postpetiole, by its smooth, shining, a foveolate sculpture, by its darker color, by its slightly stronger gastric pubescence, its more concave inner mandibular borders, and other minor details. Orectognathus sexspinosus is lighter in color and is generally more slender, with much longer teeth or spines on the alitrunk, and it has no teeth on the petiolar node.

Distribution based on Regional Taxon Lists
Australasian Region: Australia.

Nomenclature

 *  phyllobates. Orectognathus phyllobates Brown, 1958b: 25, fig. 4 (w.) AUSTRALIA. See also: Bolton, 2000: 24.

Worker
Holotype worker: TL 4.5, HL 1.12, HW (disregarding compound eyes) 0.97 (CI 87), scape L 0.78, greatest diameter of eye 0.24, ML 0.64 (MI 57), WL 1.14 (occipital lobes overlap pronotum by about 0.12 mm., an amount subtracted from WL to obtain TL), petiole L in side view 0.47, postpetiole L 0.22, gaster L 1.00, propodeal spine L 0.28 mm.

Form as shown in figure. Occipital lobes concave inside the bluntly carinate continuations of the frontal carinae; vertex convex, bituberculate centrally. Maximum depth of head about 2/3 HL. Anteocular teeth well developed, acute and sharply elevated. Mandibles strongly concave inside, even more so than in Orectognathus nigriventris, the heavy preapical convexities correspondingly stronger. The three apical teeth subequal in length; upper tooth diverging from the lower pair as seen in end-on view of mandible.

Alitrunk in the typical Orectognathus plan; pronotum depressed and marginate, with a pair of strong, acute, anteriorly .curved teeth, incrassate basally; rear of pronotum sloping through a gradual curve up to the mesonotum. Mesonotum raised in the usual manner; anterior tubercles low, blunt; posterior pair higher, more dentiform, though with extreme tips blunt. Propodeal spines strongly elevated, approximately straight in side view, diverging and slightly outcurved in dorsal view. Petiolar teeth strong, acute, curving posterodorsad, but with apices deflected. Postpetiole subtrapezoidal in dorsal view; in side view semiglobose in outline.

Body generally smooth and shining, with widely scattered inconspicuous punctulae in some areas. Sides of posterior alitrunk with some rather irregular rugosity; metanotal groove with short longitudinal costulae; costulae at base of gaster very short, almost obsolete, confined to the basal ring or groove. Funiculi and tarsi finely and densely punctulate, subopaque. Most dorsal surfaces of body, including humeral teeth, pronotum and sides of head, with a fairly abundant but short, fine and inconspicuous pilosity, mostly arched-subappressed, but becoming curved-erect on mesonotum. In Figure 4, only the pilosity of postpetiole and gaster is depicted; the gastric pilosity, in the form of a conspicuous whitish decumbent pubescence, is very even, evenly spaced, and quite distinctive. On 1egs and antennae, a dilute oblique pilosity becomes shorter and denser as a pubescence apicad.

Head, alitrunk and both nodes piceous brown (with a hint of reddish that may be due to fading), gaster deep piceous, nearly black. The general body color appears approximately black in life. Mandibles and antennae yellowish-brown, basal 2/3 of mandibles and middle of scape tending more toward light yellowish. Legs brown, with conspicuous broad bands of light straw color occupying the basal third of each of the six femora and the middle third of each of the two anterior tibiae.

Type Material
The holotype and only known species of O. phyllobates was taken at the edge of the ravine which constitutes Joalah National Park, near the top of Tamborine Mr., southeastern Queensland. The ant was taken in late afternoon from the foliage of a glossy-leaved woody plant, a shrub or young tree, about three feet above the ground. The plant was growing in a very small opening in rain forest, the result of the falling of a medium-sized tree rom the canopy. Intensive search was made of the ground cover near the plant, but no indication of the nest could be found.



References based on Global Ant Biodiversity Informatics

 * Burwell C.J., and A. Nakamura. 2011. Distribution of ant speces along an altitudinal transect in continuous rainforest in subtropical Queensland, Australia. Memoirs of the Queensland Museum -Nature 55(2): 391-411.