Cataulacus elongatus

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Cataulacus elongatus
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Crematogastrini
Genus: Cataulacus
Species: C. elongatus
Binomial name
Cataulacus elongatus
Santschi, 1924

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Specimen Label

Nothing is known about the biology of Cataulacus elongatus.

Identification

A member of the tenuis group. The abundant long, curved or sinuate, relatively soft hairs which clothe this species make it immediately recognizable amongst its congeners, The closest related known species appears to be Cataulacus pilosus but this may be distinguished by its shorter, more stocky alitrunk and marked sculptural differences, The lateral denticulations of the pronotum in elongatus are very small and may be overlooked in smaller specimens.

Keys including this Species

Distribution

Known from Angola, Congo, Gabon, Ghana, and Kenya.

Distribution based on Regional Taxon Lists

Afrotropical Region: Angola (type locality), Ghana, Kenya.

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

Nomenclature

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

  • elongatus. Cataulacus elongatus Santschi, 1924b: 221 (w.) ANGOLA. Bolton, 1974a: 34 (q.).

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 3.7 – 4.4, HL 1.00 – 1.10, HW 0.92 – 0.98, CI 89-92, EL 0.42 – 0.48, OI 45 - 49, IOD 0.68 – 0.74, SL 0.54 – 0.60, SI 58 - 61, PW 0.60 – 0.72, AL 1.00 – 1.12, MTL 0.52 – 0.58 (4 measured).

Occipital crest absent; occipital corners with a small tooth or denticle and with a second denticle on the border, close to the first. Sides of head behind eyes irregular or crenulate, but not distinctly denticulate. Development of preocular tooth variable, usually distinct but may be reduced. Sides of pronotum virtually parallel, minutely denticulate behind the acute humeral angles. Sides of alitrunk convergent behind the pronotum, often irregular but not denticulate, the mesonotum not marginate. Dorsum of alitrunk without sutures; propodeum armed with a pair of short spines. First gastral tergite not marginate laterally.

Dorsum of head with a fine, loose rugoreticulum, the interspaces of which are shallowly and weakly reticulate-punctate and shining. Dorsum of alitrunk with numerous fine, dense, rounded longitudinal rugae, almost sulcate in appearance; this sculpturation more irregular on the pronotum than elsewhere. Dorsum of petiole regularly, transversely arched-rugulose, the anterior face of the segment with a few weak transverse rugules. Posterior face of postpetiole as petiole, the dorsum rather more coarsely longitudinally rugose. First gastral tergite predominantly finely and densely reticulate-punctate, but with numerous fine or very fine irregular longitudinal rugulae.

All dorsal surfaces of head, body and appendages with abundant fine, long, narrow hairs which are usually curved or sinuate. Hairs on the vertex tend to curve forwards whilst those on the rest of the body are predominantly back-curved.

Queen

Bolton (1974) - TL 4.7, HL 1.10, HW 0.96, CI 87, EL 0.46, OI 46, IOD 0.74, SL 0.62, SI 64, PW 0.84, AL 1.30.

As worker but propodeal spines proportionally shorter and the denticulation of the pronotum less well marked. Sculpturation strongly longitudinal on all dorsal sclerites of alitrunk except the propodeum where it appears to be transverse (obscured by glue on specimen). Petiole strongly U- or V-shaped rugulose, the base of the V being posterior.

Type Material

Bolton (1974) - Holotype worker, Angola: Loanda (Le Mouli) (NM, Basle) [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 34, queen described)
  • Santschi, F. 1924b. Descriptions de nouveaux Formicides africains et notes diverses. II. Rev. Zool. Afr. (Bruss.) 12: 195-224 (page 221, worker described)