Cataulacus marginatus

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Cataulacus marginatus
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Crematogastrini
Genus: Cataulacus
Species: C. marginatus
Binomial name
Cataulacus marginatus
Bolton, 1974

Cataulacus marginatus P casent0900253.jpg

Cataulacus marginatus D casent0900253.jpg

Specimen Label

Nothing is known about the biology of Cataulacus marginatus.

Identification

A member of the granulatus group. Extremely closely related to Cataulacus granulatus; separable from that species only by the possession of a very strongly marginate first gastral tergite. As Cataulacus granulatus itself occurs on Hainan Is. there is a possibility that marginatus is only a local population of that species and further collecting may show the two forms to be intergradient. It should be stressed that the gastral margination of the new species is very strongly developed and is visible to the naked eye, and this character serves easily to distinguish the two.

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Palaearctic Region: China (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

Only known from the worker caste.

Nomenclature

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

  • marginatus. Cataulacus marginatus Bolton, 1974a: 68, fig. 38 (w.) CHINA.

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 38-41

Holotype. TL 5.3, HL 1.24, HW 1.38, CI 111, EL 0.44, OI 32, IOD 1.08, SL 0.62, SI 45, PW 1.20, AL 1.42, MTL 0.70.

Occipital crest concave, the lateral portions better developed than the median which is represented only by a row of denticles. Lateral portions of the crest denticulate, as are the sides of the head behind the eyes. Occipital corners with a small, triangular tooth. Sides of frontal carinae irregular, especially on the posterior half, but their overall outline in full-face view is very weakly convex, and convergent anteriorly. Margins of pronotum, mesonotum and propodeum strongly denticulate, with a few denticles upon the outer margins of the propodeal spines. A small gap is present separating the denticles of the pro- and mesonotum and a larger, more obvious impression or notch occurs between mesonotum and propodeum. Propodeal spines with their bases widely separated, the spines themselves narrow, acute and each one shorter than half the basal distance separating it from its twin. Petiole in dorsal view massive, notably more so than the postpetiole, both segments broader than long. In profile the anterior, dorsal and posterior surfaces of the petiole form a more or less continuous convexity. Subpetiolar process simple, truncated basally. Sides of first gastral tergite very strongly marginate, the margins prominent.

Head reticulate-rugose, the interspaces shallowly reticulate-punctate and dully shining. Dorsum of alitrunk similarly sculptured, the points of intersection of the rugae raised into minute tubercles. Declivity of propodeum transversely rugose. Sculpturation of pedicel as alitrunk but coarser, first gastral tergite very finely reticulate-rugose with reticulate-punctate interspaces. Dorsal surfaces and lateral margins of head, body and appendages with numerous short, thick, blunt whitish hairs.

Paratype. TL 4.8 – 6.0, HL 1.16 – 1.32, HW 1.30 – 1.50, CI 112 - 114, EL 0.42 – 0.46, or 31 - 32, IOD 1.02 – 1.14, SL 0.60 – 0.66, SI 43 - 46, PW 1.10 – 1.30, AL 1.28 – 1.56, MTL 0.68 – 0.76 (9 measured).

As holotype but the sculpturation of the alitrunk somewhat variable. The rugae may tend to take on an apparently longitudinal direction due to the emphasis being placed on those rugae. The cross-meshes are reduced but not lost. In some the components of the rugoreticulum are rather more broad, flattened and less sharply defined than in others.

Paratype Specimen Labels

Type Material

Holotype worker, CHINA: Hainan Is., grove near Hoi Man Chuen, S.W. of Nodoa, 4.vii.1929, Lingnan University 5th Hainan Is. expedition, 1929 (Museum of Comparative Zoology).

Paratypes. 4 workers, CHINA: Hainan Is., Ta Hau, 7.vii.1935 (J. L. Gressit) (The Natural History Museum). 1 worker, same data as above but 4-5.vii.1935 (MCZ). 4 workers, CHINA: Hainan Is., Nodoa, 15-17.vii.1935 (J. L. Gressitt) (MCZ).

References