Cataulacus greggi

AntWiki - Where Ant Biologists Share Their Knowledge
Jump to: navigation, search
Cataulacus greggi
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Crematogastrini
Genus: Cataulacus
Species: C. greggi
Binomial name
Cataulacus greggi
Bolton, 1974

Cataulacus greggi P casent0900260.jpg

Cataulacus greggi D casent0900260.jpg

Specimen Label

Nothing is known about the biology of Cataulacus greggi.

Identification

A member of the guineensis group. The affinities of this medium-sized species appear to lie with Cataulacus guineensis and Cataulacus erinaceus, especially the latter. The production of the posterolateral portions of the pronotal margination is much less distinctly developed here than in erinaceus but is none-the-less quite marked; also greggi resembles erinaceus in sculpturation, strong development of propodeal spines, development of denticulation on the head and alitrunk and form of subpetiolar process. The major differences between them, apart from the development of the pronotal margins lie in size, sculpturation of the first gastral tergite and presence in greggi of a second tooth on the occipital margin close to the dentate occipital corners. (Bolton 1974)

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

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

Distribution based on AntMaps

AntMapLegend.png

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

Nomenclature

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

  • greggi. Cataulacus greggi Bolton, 1974a: 54, fig. 22 (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

Bolton 1974 fig 22-24
TL 5.2, HL l.28, HW 1.30, CI 101, EL 0.56, OI 43, IOD 1.02, SL 0.62, SI 47, PW I.24, AL 1.40, MTL 0.70.

Occipital crest absent, the occiput and vertex confluent through an obtusely rounded angle. Occipital corners dentate, these teeth flanked upon the occipital margin by a second tooth which is almost as large as that at the corner. Sides of head behind eyes strongly denticulate, the preocular tooth well-developed, separated from eye by a rudimentary second tooth which is smaller and bluntly rounded. Humeral angles acute, the pronotum marginate and strongly denticulate laterally. This margination strongly expanded and with its posterolateral portions expanded into a low, broadly triangular extension which is denticulate upon its borders. Mesonotum and propodeum denticulate laterally but with a gap between the denticulation of the former and that of the latter. Propodeum armed with a pair of long, stout, acute, divergent spines. Sutures absent from dorsal surfaces of alitrunk. Alitrunk broadest across the pronotum, narrowed at the promesonotal junction and then of approximately equal width to the bases of the propodeal spines. Subpetiolar process complex, with a rounded but prominent anteroventral angle and a long, extended posteroventral heel or spur. Subpostpetiolar process strongly developed into a ventrally directed, simple digitiform appendage. In profile the steeply sloping anterior face of the petiole meets the sloping posterior face in a narrowly rounded angle, so that no free dorsal face is differentiated. The postpetiole has strongly sloping anterior and posterior faces separated by a broadly rounded dorsum. First gastral tergite not marginate laterally.

Dorsal surfaces of head and alitrunk with a fine but quite dense rugoreticulum, the interspaces of which are finely and densely reticulate-punctate. Declivity of propodeum with a few transverse rugae between the spines. Dorsal surfaces of pedicel predominantly coarsely and irregularly longitudinally rugose with dense interstitial punctures. First gastral tergite finely and densely reticulate-punctate with a few very weak basigastric rugulae only. All dorsal surfaces of head, body and appendages with numerous simple, blunt, stout, erect hairs.

Paratype. As holotype but slightly smaller and with relatively slightly broader heads.

TL 4.6 – 5.0, HL 1.12 – 1.20, HW 1.18 – 1.26, CI 104 -105, EL 0.50 – 0.54, OO 42 - 43, IOD 0.88 – 0.90, SL 0.60 – 0.64, SI 50, PW 1.08 – 1.16, AL 1.26 – ca 1.40, MTL 0.68 (2 measured).

Paratype Specimen Labels

Type Material

Holotype worker, ZAIRE: Ituri Forest, Epulu, vii. 1955, no. 10 (T. Gregg) (MCZ, Boston).

Paratypes. 2 workers, ZAIRE: Yangambi, x. 1956 (N. L. H. Krauss) (BMNH).

References