Cataulacus striativentris

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

Cataulacus striativentris casent0178290 profile 1.jpg

Cataulacus striativentris casent0178290 dorsal 1.jpg

Specimen labels

Synonyms

Besides a few specimens have been collected from canopy fogging samples, establishing this species as an arboreal foraging and/or nesting species , little is known about the biology of Cataulacus striativentris.

Identification

A member of the tenuis group. This small, large-eyed species is separable from similarly sculptured forms by the presence of hairs upon the dorsal surfaces of the head and body which although numerous cannot be termed abundant and are not very elongate nor sinuate. The disorganized sculpturation of the posterior half of the head capsule contrasts strongly with the regular sulcate-rugulation of the alitrunk. The form described as Cataulacus donisthorpei is, on the whole rather less coarsely sculptured than is the type of Cataulacus striativentris, and the pronotum less regularly sculptured, but otherwise the two are alike. (Bolton 1974)

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

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

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.

  • striativentris. Cataulacus wissmanni var. striativentris Santschi, 1924b: 219 (w.) DEMOCRATIC REPUBLIC OF CONGO. Raised to species and senior synonym of donisthorpei: Bolton, 1974a: 36.
  • donisthorpei. Cataulacus donisthorpei Santschi, 1937a: 61 (w.) KENYA. Junior synonym of striativentris: Bolton, 1974a: 36.

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 3.6 – 3.7, HL 0.90 – 0.94, HW 0.86 – 0.88, CI 93 - 95, EL 0.44 – 0.45, OI 50 - 51, IOD 0.62 – 0.64, SL 0.48, SI 54 - 56, PW 0.70, AL 0.94 – 0.96, MTL 0.50 (2 measured).

Occipital crest absent, the two surfaces meeting in a continuous curve. Occipital corners with a single tooth and with a second, smaller tooth beside them on the occipital border. Sides of head behind eyes finely denticulate. Sides of pronotum denticulate, the posteriormost denticle being the largest in the series. Sides of mesonotum and propodeum each with one or two denticulae; the dorsal alitrunk without trace of sutures. Propodeum bispinose, the spines rather short, broad and divergent. The pronotum is quite strongly expanded laterally and is noticeably broader than the remainder of the alitrunk. Node of petiole virtually pointed above when viewed in profile, the anterior and posterior faces sloping steeply away. Subpetiolar process with a developed posteroventral tooth, heel or spur. Subpostpetiolar process simple, long. First gastral tergite not marginate laterally.

Dorsal surface of head coarsely reticulate-rugose in the space between the eyes, and behind the eyes. In front of the anterior margin of the eyes the cross-meshes of the rugoreticulum tend to be lost, leaving this area and the clypeus longitudinally rugose. The interspaces of the occipital sculpturation are very finely and densely reticulate-punctate, and dully shining. Dorsum of alitrunk longitudinally sulcate-rugose, the sculpturation tending to be less well organized and regular on the anterior pronotum than elsewhere. Petiole and postpetiole longitudinally rugose dorsally; the first gastral tergite very closely and densely longitudinally rugose or sulcate-rugose throughout its length.

Simple, erect, blunt hairs numerous on all dorsal surfaces of the head, body and appendages. Margins of head and alitrunk with hairs projecting laterally from the marginal denticles.

Type Material

Bolton (1974):

Syntype workers, ZAIRE: Ubanghi, Banzyville (R. P. Augustin), and Haut Uele, Moto, 1920 (L. Burgeon) (NM, Basle; MRAC, Tervuren) [examined].

Cataulacus donisthorpei Syntype workers, KENYA: nos. 17 and 42 (H. Donisthorpe coIl.) (BMNH) [examined].

References