Cataulacus cestus

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Cataulacus cestus
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Crematogastrini
Genus: Cataulacus
Species: C. cestus
Binomial name
Cataulacus cestus
Bolton, 1982

Cataulacus cestus P casent0900264.jpg

Cataulacus cestus D casent0900264.jpg

Specimen Label

Nothing is known about the biology of Cataulacus cestus.

Identification

A member of the tenuis group.

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Afrotropical Region: Democratic Republic of Congo (type locality).

Distribution based on specimens

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The above specimen data are provided by AntWeb. Please see Cataulacus cestus for further details

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

Nomenclature

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

  • cestus. Cataulacus cestus Bolton, 1982: 360 (w.) DEMOCRATIC REPUBLIC OF CONGO.

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

Description

Worker

Holotype. TL 4.0, HL 1.00, HW 0.99, CI 99, EL, 0.45, OI 45, SL 0.48, SI 48, PW 0.76, AL 1.10.

Sides of head behind eyes denticulate, terminating in a larger denticle at the occipital corner. Occipital crest absent but the occipital surface shallowly concave above the foramen and meeting the dorsum in an angle, the two surfaces not evenly rounded together. Occipital margin unarmed except for a denticle or short tooth close to the one at the corner. Eyes relatively small, OI < 50. With the alitrunk in profile the dorsum evenly shallowly convex between the more steeply sloped anterior portion of the pronotum and the base of the propodeal spines. Pronotal and propodeal surfaces beset with small peaks or tubercles in profile, the mesonotal dorsum also having such peaks but they are here more scattered and much lower, having the appearance of minute irregularities in the outline. Mesokatepisternal tooth small. Metapleural lobes rounded. Propodeal spines in profile short, more or less straight, only very slightly elevated. Alitrunk in dorsal view with the pronotal corners denticulate, the lateral marginations of the pronotum behind the corners with 6-7 sharp triangular denticles projecting laterally. Sides of mesonotum with 1-2 small denticles and sides of propodeum also with 1-2, occurring on the convexity over the spiracle. Propodeal spines short and broad, widely divergent. Petiole node in profile rising to an acute peak dorsally. The subpetiolar process with a rounded and slightly prominent anteroventral lobe and a triangular projecting posteroventral tooth or heel; the ventral surface between the two angles feebly concave. Postpetiole in profile high, its dorsal surface with a number of conspicuous peaks or tubercles and its ventral process short-digitiform. Dorsum of head irregularly reticulate-rugose, the meshes of varying size and the rugae low and rounded. Many of the reticular meshes incomplete or with their walls broken. Ground-sculpture within the meshes a very fine superficial shagreening or granular roughening of the surface, not reticulate-punctate. Dorsal alitrunk irregularly reticulate-rugose everywhere, many of the rugular meshes incomplete or broken and very irregular in shape. Ground-sculpture finely reticulate-punctate to densely shagreened. Petiole node in dorsal view strongly longitudinally rugose, the rugae converging posteriorly. Postpetiole irregularly rugulose and finely densely punctulate. First gastral tergite coarsely and densely reticulate-punctate everywhere, the whole surface also loosely covered with anastomosing fine irregular superficial rugulae which are strongest basally and fade out apically on the sclerite. First gastral sternite similarly sculptured. Entire dorsum of head covered with a dense pelt of short straight erect bristly blunt hairs which are cylindrical to subcylindrical in shape. All remaining dorsal surfaces of body with similar dense bristly pilosity. Colour uniform black; the scapes, tibiae and tarsi dull yellow.

Paratypes. TL 4.0-4.1, HL 0.98-1.02, HW 0.98-1.02, CI 98-100, EL 0.45-0.48, OI 46-47, SL 0.48-0.50, SI 49-51, PW 0.76-0.86, AL 1.08-1.16 (4 measured).

As holotype but in some the gastral rugulae are less strongly developed and in one the gastral rugulae are effaced. The ventral surface of the subpetiolar process may be more strongly concave than is the case with the holotype.

Type Material

Holotype worker, Zaire (B. Congo on data label); Ituri For., Beni-Irumu, ii.1948, no. 2122 (N. A. Weber) (Museum of Comparative Zoology). Paratypes. 1 worker with same data as holotype; 1 worker with same data as holotype but no. 2120; 2 workers with same data as holotype but no. 2119. (MCZ; The Natural History Museum).

References