Smith, F., 1860
Nothing is known about the biology of Cataulacus setosus.
A member of the granulatus group, Cataulacus setosus is separated from the majority of the species by its long propodeal spines, a character more in keeping with the species of the taprobanae-group. It is quickly distinguishable from Cataulacus nenassus, its closest relative, by the different gastral sculpturation in the latter, which has longitudinal rugulation over the entirety of the first tergite.
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Much of the information concerning the biology of Cataulacus species is anecdotal and fragmentary. Arnold (1917) wrote a succinct general overview of Cataulacus biology that still remains quite informative. Arnold reports "all the species of this genus are tree-ants, usually forming medium sized nests in hollow twigs and stems, or more rarely, under the bark. They are timid and slow-moving insects, often feigning death or dropping rapidly to the ground when disturbed. As Bingham has remarked in connection with this genus (Fauna Brit. India, Formicidae), these ants have the habit of wandering over the trunks of trees and the leaves in what appears to be a very aimless and languid manner. I have occasionally seen them breaking open the earthen tunnels constructed by termites over the trunks of trees and attack the inmates."
Bolton (1974) expands upon this earlier account - "All known Cataulacus species are arboreal or subarboreal nesters and they predominantly forage on the trees and shrubs in which the nests are situated. Very few appear to come down to ground level but in West Africa the small species Cataulacus pygmaeus and Cataulacus brevisetosus may be found foraging in leaf litter or crossing the ground to ascend a tree other than the one in which the nest is situated. The nests themselves are usually constructed in small hollow twigs or stems by the smaller species and in rotten branches or rotted portions of the tree trunk by the larger species. This is rather a generalization as some small species are known which nest in and under rotten bark (e.g. Cataulacus vorticus) and undoubtedly some of the larger forms will eventually be found inhabiting relatively small cavities in plants.
Various species of the genus in Africa are known to inhabit a variety of galls, acacias and bushes as well as large trees. Numerous species have been found nesting in, and have therefore been often collected from, cocoa in Africa. Some of these species are Cataulacus guineensis, Cataulacus pygmaeus, Cataulacus mocquerysi, Cataulacus egenus, Cataulacus vorticus, Cataulacus brevisetosus, Cataulacus kohli and Cataulacus theobromicola. Feeding habits in the genus are mostly unknown but the present author has noted C. guineensis tending aphids and small coccids.
On the plants ants of the genus Cataulacus often occur together with Oecophylla or species of Crematogaster, and appear to be mostly tolerated (at least they are not evicted) by the majority of these forms. Their defence against attackers of these genera lies primarily in their armoured exterior, but their ultimate escape reaction is to curl up and release their grip on the plant, falling to the ground and thus making their escape. The decision to remain immobile and present an armoured surface or to drop from the plant appears to depend upon the size or persistence of the aggressor; larger attackers usually precipitate the latter reaction, but it has also been noted as a result of persistent and unwanted attention by a series of workers of a small Crematogaster species.
The majority of species are forest-dwelling forms, with relatively few adapted to savannah or veldt conditions. Those which do, however, occur in these zones tend to be very successful in their chosen habitat and often possess a wide distribution. A few species are apparently able to exist in any region of Africa providing the basic essentials of nesting-site and food supply are met with, but on the whole the fauna may be divided into forest and non-forest forms."
Some species have nests that can be protected by a single worker's head, as its shape matches the nest entrance and forms an effective plug.
It has more recently been discovered that some species of Cataulacus are efficient gliders (Cataulacus erinaceus, Cataulacus guineensis, Cataulacus mocquerysi and Cataulacus tardus). Workers exhibit directed movement while in freefall that allows them to glide back to regain a hold on the same tree trunk. (Yanoviak et al. 2005, 2007, 2008)
The following information is derived from Barry Bolton's New General Catalogue, a catalogue of the world's ants.
- setosus. Cataulacus setosus Smith, F. 1860b: 114, pl. 1, fig. 7 (w.) INDONESIA (Batjan I.). Smith, F. 1863: 24 (q.). See also: Bolton, 1974a: 71.
Holotype worker in Oxford University Museum of Natural History. Labelled “Bac. 31.”
Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.
Bolton (1974) - TL 4.1 – 4.2, HL 1.06 – 1.08, HW 1.16 – 1.20, CI 109 - 111, EL 0.40 – 0.42, OI 34 - 36, IOD 0.90 – 0.96, SL 0.58 – 0.62, SI 50 - 52, PW 0.92 – 1.07, AL 1.08 – 1.18, MTL 0.58 – 0.62 (5 measured).
Occipital crest complete, with dentic1es throughout its length. Sides of head behind eyes denticulate, the occipital corners with a small tooth which is, however, larger than either the dentic1es of the sides or of the occipital crest. Sides of pronotum marginate, the margins strongly denticulate. Sides of mesonotum and propodeum denticulate, the dentic1es extending onto the outer margins of the propodeal spines. Propodeal spines long, broad basally and tapering to an acute apex, each spine at least as long as half the distance separating it from its twin. Sides of first gastral tergite not margined but with a few small to minute dentic1es or prominences on the basal quarter of the sides when the gaster is examined in dorsal view.
Sculpturation of head and alitrunk coarse, conspicuous and somewhat variable. Dorsum of head posteriorly with a distinct rugoreticulum and with reticulate-punctate interspaces. Anteriorly the rugae tend to have a longitudinal direction, usually restricted to the area in front of the level of the anterior ocular margin although occasionally the rugoreticulum may extend almost to the clypeus. Pronotal dorsum strongly but rather loosely reticulate-rugose, the points of intersection of the rugae raised into small prominences; the interspaces reticulatepunctate. Mesonotal and propodeal dorsa sculptured as pronotum or with the sculpturation less intense, or with the rugae tending to assume a roughly longitudinal pattern. First gastral tergite densely and rather coarsely reticulate-punctate with fine longitudinal rugulae present basally and on the sides of the sclerite. The disc bears only the basic puncturation or has a few disorganized, short, broken rugulae.
Short, thick, blunt erect hairs numerous and conspicuous upon all dorsal surfaces of the head, body and appendages.
Bolton (1974) - TL 5.5 – 5.9, HL 1.22 – 1.26, HW 1.34, CI 106 - 109, EL 0.46 – 0.48, OI 34 - 36, IOD 1.06 – 1.08, SL 0.64 – 0.72, SI 48 - 54, PW 1.22 – 1.26, AL 1.68 – 1.76, MTL 0.72 – 0.74 (2 measured).
As worker but dentic1es on sides of head reduced, as are those on the sides of the alitrunk in dorsal view. Propodeal spines short and broad, acute. Sculpturation of head and pronotum as described above, but with the cephalic rugae having a more distinct longitudinal direction than in the worker. The mesothoracic sc1erites and the propodeum are longitudinally rugose dorsally with the interspaces finely reticulate-punctate.
Bolton (1974) - Holotype worker, INDONESIA: Moluccas, Batjan (=Batchian) Island (A. R. Wallace) (UM, Oxford) [examined].
- Bolton, B. 1974a. A revision of the Palaeotropical arboreal ant genus Cataulacus F. Smith (Hymenoptera: Formicidae). Bull. Br. Mus. (Nat. Hist.) Entomol. 30:1-105. (page 71, see also)
- Smith, F. 1860b. Catalogue of hymenopterous insects collected by Mr. A. R. Wallace in the islands of Bachian, Kaisaa, Amboyna, Gilolo, and at Dory in New Guinea. J. Proc. Linn. Soc. Lond. Zool. 5(17b)(suppl. to vol. 4 4: 93-143 (page 114, pl 1, fig. 7 worker described)
- Smith, F. 1863a. Catalogue of hymenopterous insects collected by Mr. A. R. Wallace in the islands of Mysol, Ceram, Waigiou, Bouru and Timor. J. Proc. Linn. Soc. Lond. Zool. 7: 6-48 (page 24, queen described)