Nothing is known about the biology of Cataulacus tenuis.
A member of the tenuis group. Both descriptions (Emery 1899, Santschi 1913) stress the fact that the head is about one quarter longer than it is wide. This gives a CI in the region of 75, by far the lowest yet recorded in the genus. If this is so then the species can be easily recognized on that single character plus the fact that it is restricted to Madagascar, but the following features are also of note. Any specimen from Madagascar combining a relatively very long and narrow head with the above series of characters should be recognizable as Cataulacus tenuis. (Bolton 1974)
Keys including this Species
Distribution based on Regional Taxon Lists
Distribution based on AntMaps
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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.
- tenuis. Cataulacus tenuis Emery, 1899f: 288 (q.) MADAGASCAR. Santschi, 1913c: 310 (w.). See also: Bolton, 1974a: 37.
Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.
Bolton (1974) - TL 3.5. Occipital corners projecting as broad teeth; the sides of the head behind the eyes without dentic1es. Sides of alitrunk marginate, denticulate; the propodeum with a pair of short spines. Head and alitrunk longitudinally rugose with an irregular reticulation upon the pronotum. First gastral tergite reticulate-punctate with longitudinal striae upon the basal third. Sparse pilosity is present upon the head and alitrunk.
Bolton (1974) - TL 5.0. As above but Emery (1899) states that the occipital corners of the head are acute and projecting. The c1ypeus is longitudinally striate but the remainder of the head is more or less reticulate-rugose, as is the pronotum. Mesoscutum and scutellum predominantly irregularly longitudinally rugose; propodeal spines short.
Bolton (1974) - Holotype female, MADAGASCAR: Antongil Bay, 1897-98 (Mocquerys) (possibly in MCSN, Genoa). I have not been able to examine the type of this species, nor have I seen the worker which was described by Santschi (1913 : 310) and was based upon a single individual recovered by J. de Gaulle in Madagascar, at an unnamed location. However, the two descriptions are so similar in their salient features that Santschi appears to have correctly associated his single worker with the type female.
- 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 37, see also)
- Emery, C. 1899e. Formiche di Madagascar raccolte dal Sig. A. Mocquerys nei pressi della Baia di Antongil (1897-1898). Bull. Soc. Entomol. Ital. 31: 263-290 (page 288, queen described)
- Santschi, F. 1913c. Glanures de fourmis africaines. Ann. Soc. Entomol. Belg. 57: 302-314 (page 310, worker described)