Rhopalothrix orbis

The holotype was collected from rainforest leaf litter.

Identification
Key to Rhopalothrix workers / Key to Old World Basicerotini

Distribution based on Regional Taxon Lists
Australasian Region: Australia.

Nomenclature

 *  orbis. Rhopalothrix orbis Taylor, 1968b: 336, figs. 1-3 (w.) AUSTRALIA. Taylor, 1970a: 49 (q.).

Worker
Holotype - Dimensions are as follows: TL, c.2•6; HL, 0.61; HW, 0.66; CI, 108; ML, 0.20, MI, 33; WL, 0.66.

Ttransverse frontal sulcus lacking. Eyes minute, situated as in R. diadema. Mandibles narrow; distal half of inner border with 3 crowded, subequal, apically directed, minute denticles; proximal half of inner border edentate; teeth of apical complex as in R. diadema. Labrum lacking a mediobasal tumulus.

Mesosoma compact; summit at posterior edge of mesonotum, metanotal groove impressed, propodeal dorsum strongly convex, propodeal teeth distinct (compare R. diadema). Humeri rounded in dorsal view. Pronotum broader than long, its maximum width 0.41 mm (0.62 times HW, and twice width of propodeal dorsum). Promesonotal sulcus vestigial on mesosomal dorsum. Metanotal groove with several weak transverse ribs. Propodeal dorsum inflated, forming a transverse elliptical welt, which descends abruptly behind towards the bases of the propodeal teeth; the latter parallel in dorsal view, and the propodeal declivity slightly concave. Petiole and postpetiole generally as in R. diadema. Postpetiole almost exactly twice the width of petiole and 0.7 times as wide as first gastric tergite. The latter 0.59 mm wide; almost precisely as broad as long. Entire body densely and finely granulose-punctate and opaque. Ground pilosity of white, orbicular, subappressed, squamiform hairs, distributed as in R. diadema, but more abundant, especially on postpetiole and gaster, and less variable in size, especially on head and its appendages. Larger specialized hairs similar in structure and distribution to those of R. diadema, except only 8 in anterior arc on head, and 6 on first gastric tergite. Those on the latter form a posterior marginal row across the sclerite, which otherwise bears hairs of a single size class, unlike R. diadema. Colour almost uniformly medium reddish brown, darker than in R. diadema.

Paratype - Except for its larger size, this specimen agrees with the holotype in all apparently significant features. It has the following dimensions: TL, c.2.8; HL, 0.62; HW, 0.69; CI, 111; ML, 0.22; MI, 35; WL, 0.70; PW, 0.44; width of first gastric segment, 0.66. The enlarged hairs of the first gastric tergite are proportionately smaller than in the holotype.

Type Material
Holotype worker Australia: Queensland: Tamborine Mountain, north side near Curtis Falls (Berlese funnel sample, leafmould, rain forest), 8.v.l953, T. E. Woodward. Deposited in (Type No. 7503).

Paratype worker Queenslands: Rathdowney, Philp's Farm, Lever's Plateau (Berlese funnel sample, leaf litter, rain forest), 13.iii.1966, J. B. Williams. Deposited in QM.