Cataulacus adpressus

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Cataulacus adpressus
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Crematogastrini
Genus: Cataulacus
Species: C. adpressus
Binomial name
Cataulacus adpressus
Bolton, 1974

Cataulacus adpressus P casent0900267.jpg

Cataulacus adpressus D casent0900267.jpg

Specimen Label

Besides the type being collected from "pyrethrum knockdown", little is known about the biology of what we presume is an arboreal nesting species.

Identification

A member of the tenuis group. The combined characters of size, sculpturation, and the remarkable adpressed hairs immediately identify this species and serve to separate it from the other species related to Cataulacus brevisetosus.

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Afrotropical Region: Ghana (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

Only known from the worker caste.

Nomenclature

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

  • adpressus. Cataulacus adpressus Bolton, 1974a: 30, figs. 15, 18 (w.) GHANA.
Bolton 1974 fig 15-21

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 3.5, HL 0.90, HW 0.82, CI 91, EL 0.44, OI 54, OOD 0.58, SL ca 0.42, SI ca 50, PW 0.69, AL 0.90, MTL 0.44.

Occipital crest absent; occipital corners each armed with a single low, blunt denticle. Sides of head behind eyes uneven but not denticulate, convergent close to the occipital corners. Preocular tooth small, separated from the eye by a small gap. Pronotum marginate laterally, the humeral angles acute; margination with a number of extremely minute denticles and terminating posteriorly in a single larger denticle close to the promesonotal junction. Mesonotum and propodeum not marginate, without denticles; propodeal spines short and bluntly rounded apically. Promesonotal suture represented upon the dorsum by a very weak impression which does not break the sculpturation and is best visible at the sides where it joins a small, shallow notch separating the pro- and mesonota. Metanotal groove absent. Sides of pronotum in dorsal view more or less parallel, only very slightly convergent posteriorly; those of the mesonotum shallowly convex and convergent posteriorly, separated from the propodeum by a shallow, very broadly V-shaped impression. Propodeal sides with a bluntly convex swelling anteriorly, converging behind to the bases of the spines. First gastral tergite not marginate laterally.

Dorsum of head finely reticulate-rugose, the interspaces finely and densely reticulate-punctate. Dorsum of alitrunk finely regularly longitudinally sulcate with a few transverse sulci between the propodeal spines. Sides of alitrunk obliquely sulcate, those on the propodeum almost vertical. Femora longitudinally sulcate. Anterior surface of petiole and posterior surfaces of both petiole and postpetiole transversely sulcate, but the anterior and dorsal faces of the latter longitudinally so. First gastral tergite with fine, dense longitudinal rugulae throughout its length.

Hairs on all dorsal surfaces of the body from the clypeus to the apex of the first gastral tergite strongly adpressed, sparse, most easily visible upon the clypeus, propodum, postpetiole and gaster. Normal standing hairs present only upon the mandibles, margins of the frontal carinae and extreme gastral apex. A few strongly ad pressed hairs present upon the dorsal surfaces of the femora.

Holotype Specimen Labels

Type Material

Holotype worker, GHANA: Bunso (eastern region), 8.vii.1969, by pyrethrum knockdown (D. Leston) (The Natural History Museum).

References