Cataulacus pilosus

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Cataulacus pilosus
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Crematogastrini
Genus: Cataulacus
Species: C. pilosus
Binomial name
Cataulacus pilosus
Santschi, 1920

Cataulacus pilosus P casent0280810.jpg

Cataulacus pilosus D casent0280810.jpg

Specimen Label

Bequaert (1922) records the species as nesting in the myrmecophilous plant Cuviera angolensis Hiern.

Identification

A member of the tenuis group. Bolton (1974) - This short and rather stocky species can immediately be recognized by the presence of dense, long, fine hairs on all dorsal surfaces of the body, and by the transverse sculpturation upon the propodeum, a combination of characters not shared with any other known species. The erect hairs are in fact noticeably longer than is normal in the genus and, proportional to their length, they are also much finer.

The female of the species was described by Santschi in the same publication as the worker and appears to be essentially similar in form, with the mesoscutum and scutellum longitudinally striate-rugose.

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Afrotropical Region: Democratic Republic of Congo (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

Nomenclature

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

  • pilosus. Cataulacus pilosus Santschi, 1920c: 118 (w.q.) DEMOCRATIC REPUBLIC OF CONGO. See also: Bolton, 1974a: 35.

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 3.1, HL 0.82, HW 0.80, CI 97, EL 0.40, OI 50, IOD 0.64, SL 0.44, SI 55, PW 0.56, AL 0.82, MTL 0.40.

Occipital crest absent; occipital corners armed with one or two denticles which are not much larger than those on the sides of the head behind the eyes. Preocular tooth relatively large and triangular. Eyes widely separated, the surface beween them convex. Margins of alitrunk irregular but not denticulate, although one or two minute, tuberculiform denticulae may be present just posterior to the acute humeral angles. In the syntype worker these are better developed on the right hand side than on the left. Propodeum armed with a pair of very short spines. In dorsal view the sides of the pronotum are virtually parallel, but behind this they converge posteriorly. However, there is no abrupt, sharp-angled narrowing behind the pronotum. Dorsal alitrunk without sutures or vestiges of sutures. First gastral tergite not marginate laterally.

Dorsum of head covered with a fine rugoreticulum, the interspaces of which are densely reticulate-punctate. Pronotal dorsum similarly sculptured but on the mesonotum the cross-meshes are lost, and this area is closely and distinctly longitudinally rugose, almost sulcate-rugose; the constituents somewhat wavy, especially towards the outer margins of the sclerite. Propodeum with fine, dense, arched-transverse rugulation, similarly the posterior face of the petiole and the postpetiole. Dorsum of postpetiole with a few short, longitudinal rugae. First gastral tergite finely and densely but brokenly and unevenly longitudinally rugulose, with reticulate-punctate interspaces.

Entirety of dorsum, but especially the head, abundantly equipped with long, fine, erect hairs, many of which are curved.

Type Material

Bolton (1974) - Syntype worker, female, ZAIRE: Avakubi, 6.1.1914 (Bequaert) (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 35, see also)
  • Santschi, F. 1920c. Fourmis nouvelles du Congo Belge. Rev. Zool. Afr. (Bruss.) 8: 118-120 (page 118, worker, queen described)