Cataulacus pullus

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Cataulacus pullus
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Crematogastrini
Genus: Cataulacus
Species: C. pullus
Binomial name
Cataulacus pullus
Santschi, 1910

Cataulacus pullus P casent0217088.jpg

Cataulacus pullus D casent0217088.jpg

Specimen Label

Synonyms

Nothing is known about the biology of Cataulacus pullus.

Identification

A member of the huberi group. In the specimens so far examined the structure of the pronotal margination has been reasonably consistent; but in view of the variability of this region in closely related species (huberi, etc.) it is to be expected that specimens will eventually be found which differ in this respect from the above description. The species is perhaps best distinguished by the characters used to separate it in the key. (Bolton 1974)

Keys including this Species

Distribution

Known from Congo, Guinea and Kenya.

Distribution based on Regional Taxon Lists

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

  • coriaceus. Cataulacus coriaceus Stitz, 1910: 138, fig. 7 (w.) CAMEROUN. Junior synonym of pullus: Bolton, 1974a: 26.
  • pullus. Cataulacus pullus Santschi, 1910c: 387, fig. 13 (w.) CONGO. Senior synonym of coriaceus, orientalis: Bolton, 1974a: 26.
  • orientalis. Cataulacus pullus var. orientalis Santschi, 1914b: 108 (w.) KENYA. Junior synonym of pullus: Bolton, 1974a: 26.

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 5.3 – 7.0, HL 1.32 - 1.84, HW 1.58 – 2.16, CI 117 - 119, EL 0.42 – 0.54, OI 25-28, IOD 1.18 – 1.70, SL 0.80 – 1.02, SI 49-53, PW 1.24 – 1.60, AL 1.60 – 2.04, MTL 0.90 - 20 (3 measured).

Bolton 1974 fig 10-12
Occipital crest absent, the vertex curving into the occipital surface which is shallowly concave in larger workers. Occipital corners with a single, broad triangular or subtriangular denticle or tooth, which is usually continued towards the midline as a short, sharp ridge. Sides of head between eyes and occipital corners denticulate or crenulate or merely irregular in largest workers. Pronotum marginate laterally, the remainder of the alitrunk not marginate, the dorsum curving into the sides. On the pronotum the margination is expanded laterally, beginning just behind the acute humeral angles, and usually bears two teeth. The anterior of these two teeth is larger and is separated by a distinct gap from the posterior teeth; this latter is situated towards the posteriormost point of the pronotal margination, which peters out before the junction with the mesonotum. Promesonotal suture absent or its track marked by an extremely faint impression, showing its former position. Propodeum with a pair of long, acute slightly divergent spines. Ventral processes of petiole and postpetiole well developed, the former usually showing a well developed posteroventral tooth or spur; the latter short, spiniform or dentiform. First gastral tergite not marginate laterally.

Dorsum of head extremely finely, densely and shallowly reticulate-punctate, dully shining; the whole surface except the clypeus overlaid by a fine, loose, disorganised rugoreticulum. Pronotum, especially on anterior half, sculptured as head, but on the remainder of the dorsal alitrunk the rugulae tend to take on a distinct longitudinal trend. In smaller workers the rugulae may be reduced or absent on the mesonotum, leaving the sclerite merely reticulate-punctate. Petiole and postpetiole coarsely rugose, the rugae often directed longitudinally upon the former. First gastral tergite reticulate-punctate or also with a fine rugoreticulum.

Erect hairs absent from dorsal surfaces of head behind clypeus and dorsum of alitrunk, present upon clypeus, lateral margins of head, pedicel, appendages, and usually also on first gastral tergite.

Type Material

Bolton (1974):

Holotype worker, CONGO (BRAZZAVILLE): Brazzaville (A. Weiss) (NM, Basle) [examined].

Cataulacus coriaceus Holotype worker, CAMEROUN: Mundame (Conradt) (MNHU, Berlin) [examined].

Cataulacus pullus var. orientalis Holotype worker, KENYA: Voi, alt. 600 m, st. no. 60, iii. 1912 (Alluaud b Jeannel) (NM, Basle) [examined].

References