Cataulacus regularis

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Cataulacus regularis
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Crematogastrini
Genus: Cataulacus
Species: C. regularis
Binomial name
Cataulacus regularis
Forel, 1892

Cataulacus regularis casent0101240 profile 1.jpg

Cataulacus regularis casent0101240 dorsal 1.jpg

Specimen labels

Cataulacus regularis is found in a variety of forest habitats in Madagascar.

Identification

A member of the huberi group. The sculpturation seen in Cataulacus regularis is very uncommon, being met with only in one other Madagascan species, the seemingly closely related Cataulacus porcatus. This latter species is, however, smaller and has some erect hairs on the dorsal alitrunk, besides differences in sculpturation, In species of other groups in which at least the alitrunk is longitudinally sulcate there are other marked differences, most obvious amongst which are presence of hairs or denticles or both upon the alitrunk, and marked differences in the shape of this portion of the body.

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Malagasy Region: Madagascar (type locality).

Distribution based on AntMaps

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Distribution based on AntWeb specimens

Check data from AntWeb

Biology

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)

Castes

Worker

Queen

Nomenclature

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

  • regularis. Cataulacus regularis Forel, 1892l: 252 (w.) MADAGASCAR. See also: Bolton, 1974a: 27.

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

Description

Worker

Bolton (1974) - TL 5.3 – 5.9, HL 1.22 – 1.32, HW 1.30 – 1.32, CI 100 – 107, EL 0.42 – 0.46, OI 32 - 35, IOD 1.04 – 1.06, SL 0.68 – 0.72, SI 52 - 54, PW 1.10 – 1.18, AL ca 1.68, MTL 0.66 – 0.70 (2 measured).

Bolton 1974 fig 13-14
Lateral portions of occipital crest developed, unarmed. Medially the crest is very poorly developed, concave or broadly V-shaped in full-face view. Sides of head behind eyes smooth, not denticulate. Occipital corners irregular or with one or two obtuse, low prominences, not armed with teeth or spines. Sides of alitrunk without denticles. Humeral angles acute, separated by a short but marked concavity from the beginnings of the pronotal margination; the latter joining the mesonotum at a slight notch. Promesonotal suture visible as an impression across the sculpturation but not breaking it. Mesonotal margination ending in a triangular, dentiform process posteriorly, in front of a distinct notch separating mesonotum from propodeum, Propodeal marginations strongly convex anteriorly, converging behind to a pair of short, narrow, virtually parallel spines. Petiole longer than broad in dorsal view, with a small but distinct laterally projecting tooth at about the mid length on either side. In profile the petiole somewhat flattened, with a steep anterior face and a long, somewhat sloping dorsal face; without a differentiated free posterior surface before the junction with the postpetiole. Subpetiolar process complex, with a tooth posteroventrally. Anterior subpostpetiolar process variable in size but simple. Sides of postpetiole in dorsal view with one or two denticles. Gaster not marginate laterally.

Dorsal surfaces of head behind clypeus, alitrunk, petiole and postpetiole strongly sculptured with regular, parallel longitudinal sulci, the spaces between the sulci broadly convex and giving the cuticle a ploughed appearance. The pronotal sulci are slightly wavy in the larger specimen examined, much more regularly organized in the smaller. First gastral tergite finely reticulate-punctate with a few scattered, fine, longitudinal rugulae. Clypeus sculptured much as rest of head but more finely so, and with a tendency for the sulci to fade out anteriorly.

Syntype Specimen Labels

Dorsal surfaces of head and alitrunk and margins of alitrunk without hairs. Short hairs are present upon the petiole, postpetiole, apex of first gastral tergite and margins of frontal carinae; appendages with numerous short, erect hairs.

Type Material

Bolton (1974) - Syntype workers, Madagascar: Bezanozano, Anosibe (Sikora) (MHN, Geneva) [examined].

References

  • 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 27, see also)
  • Forel, A. 1892o. Les Formicides. [concl.]. In: Grandidier, A. Histoire physique, naturelle, et politique de Madagascar. Volume XX. Histoire naturelle des Hyménoptères. Deuxième partie. Supplèment au 28e fascicule. Paris: Hachette et Cie, pp. 229-280. (page 252, worker described)