| Cataulacus tardus|
Cataulacus tardus was found nesting in the canopy of a secondary-forest tree, in sampling conducted in tree crowns, in Gamba, Gabon. It was anecdotally reported to subordinate at tuna baits. C. tardus has been shown to exhibit directed movement while in freefall that allows workers that fall or purposely detach from a tree to glide back and regain a hold on the same tree trunk. This gliding behavior is shared with numerous members of the tribe Cephalotini, and other genera as well. (Yanoviak et al. 2005, 2007, 2008)
A member of the huberi group. Santschi notes that Cataulacus schoutedeni is close to Cataulacus tardus, but is smaller, the (propodeal) spines relatively longer, the sculpture more feeble'. Variations of this form are usual and may be universal amongst species of the huberi group, and the only real difference separating the types of the two forms in the present species (apart from obvious size differences) is the presence of an angle separating the vertex from the occiput in tardus, absent from schoutedeni. As has been noted the occurrence of this angle is restricted to large workers of the species and no grounds remain for maintaining the two names as separate species. (Bolton 1974)
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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.
- tardus. Cataulacus tardus Santschi, 1914d: 372, fig. 33 (w.) GUINEA. Senior synonym of schoutedeni: Bolton, 1974a: 27.
- schoutedeni. Cataulacus schoutedeni Santschi, 1919c: 248 (w.q.) DEMOCRATIC REPUBLIC OF CONGO. Junior synonym of tardus: Bolton, 1974a: 27.
Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.
Bolton (1974) - TL 5.4 – 6.8, HL 1.40 – 1.70, HW 1.58 – 1.96, CI 113 - 117, EL 0.44 – 0.54, IO 22 - 28, IOD 1.20 – 1.48, SL 0.84 – 0.98, SI 50 - 51, PW 1.24 – 1.56, AL 1.54 – 1.86, MTL 0.88 – 0.94 (7 measured).
Dorsum of head extremely finely, densely and faintly reticulate-punctate, with a loose, very fine, scattered rugoreticulum. In some specimens the rugulation is effaced or nearly so over some areas of the cephalic dorsum. Dorsal alitrunk similarly sculptured but with the rugulae tending to assume a longitudinal direction. First gastral tergite predominantly or totally finely reticulate-punctate, but in some specimens a few very faint rugulae are visible.
Dorsal surfaces of head, alitrunk and gaster without hairs. Margins of head behind eyes and margins of alitrunk without hairs, or the former with one or two minute hairs which, however, do not project freely beyond the margin.
Holotype worker, GUINEA: Mamou, 24.viii.1912 (Silvestri) (NM, Basle) [examined].
Syntype workers, female, Zaire: Congo da Lemba, i-ii.1913 (R. Mayne) (NM, Basle; MRAC, Tervuren) [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. PDF (page 27, Senior synonym of schoutedeni)
- Santschi, F. 1914d. Formicides de l'Afrique occidentale et australe du voyage de Mr. le Professeur F. Silvestri. Boll. Lab. Zool. Gen. Agrar. R. Sc. Super. Agric. 8: 309-385 (page 372, fig. 33 worker described)
- Yanoviak, S. P., R. Dudley, and M. Kaspari. 2005. Directed aerial descent in canopy ants. Nature. 433:624-626.
- Yanoviak, S. P., B. L. Fisher, and A. Alonso. 2007. Arboreal ant diversity (Hymenoptera: Formicidae) in a central African forest. African Journal of Ecology. 46:60-66.
- Yanoviak, S. P., B. L. Fisher, and A. Alonso. 2008. Directed aerial descent behavior in African canopy ants (Hymenoptera: Formicidae). Journal of Insect Behavior. 21:164-171.