Rhopalothrix orbis

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Rhopalothrix orbis
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Attini
Genus: Rhopalothrix
Species: R. orbis
Binomial name
Rhopalothrix orbis
Taylor, 1968

Rhopalothrix orbis casent0172459 profile 1.jpg

Rhopalothrix orbis casent0172459 dorsal 1.jpg

Specimen labels

The holotype was collected from rainforest leaf litter.

Identification

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Australasian Region: Australia (type locality).

Distribution based on AntMaps

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Distribution based on AntWeb specimens

Check data from AntWeb

Biology

Longino and and Boudinot (2013) - Knowledge of the biology of the Rhopalothrix isthmica clade of Rhopalothrix is conjectural; a nest has never been recovered and a live specimen never seen. What we know is based on locations and frequencies of capture using various mass-sampling methods. Specimens are known from wet to moderately seasonal forest, from sea level to 2140 m elevation. At higher elevation, they are found in diverse mesophyll forest and in forests with various combinations of Liquidambar and montane oak. In Costa Rica, they are restricted to the wet forests of the Atlantic slope, to 1500 m on the Barva Transect in the Cordillera Volcánica Central and to 800 m in the Cordillera de Tilarán. The genus is unknown from the Monteverde cloud forest at 1500 m, the lowland wet forests of the Osa Peninsula, and the lowland tropical dry forests of Guanacaste, in spite of intensive collecting efforts in these areas. Further north in Central America they can occur at higher elevations.

In quantitative sampling at La Selva Biological Station, in the Atlantic lowlands of Costa Rica, occurrences were relatively more frequent in soil/litter cores than in samples of sifted litter from the soil surface. This suggests that nests are subterranean, with workers only occasionally venturing up into the litter layer. Dealate queens are known for a few species, occurring occasionally in Winkler or Berlese samples. Alate queens of one La Selva species were found in canopy fogging samples, one each in two separate fogging events. Oddly, alate queens have not been found in the many Malaise samples from La Selva. Males remain unknown.

Castes

Nomenclature

The following information is derived from Barry Bolton's New General Catalogue, a catalogue of the world's ants.

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

Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.

Description

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 Specimen Labels

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 Australian National Insect Collection (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.

  • Holotype, worker, Tamborine Mt., north side near Curtis Falls, Queensland, Australia, 8 May 1953, Woodward,T.E., ANIC32-017702, Australian National Insect Collection; berlese funnel sample, leafmould, rainforest.
  • Paratype, 1 worker, Rathdowney, Philps Farm, Lever Plateau, Rathdowney, Queensland, Australia, Williams,J.B., ANIC32-017703, Australian National Insect Collection.

References

  • Taylor, R. W. 1968c. Notes on the Indo-Australian basicerotine ants (Hymenoptera: Formicidae). Aust. J. Zool. 16: 333-348 (page 336, figs. 1-3 worker described)
  • Taylor, R. W. 1970a. Notes on some Australian and Melanesian basicerotine ants (Hymenoptera: Formicidae). J. Aust. Entomol. Soc. 9: 49-52 (page 49, queen described)