Cataulacus simoni

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Cataulacus simoni
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Crematogastrini
Genus: Cataulacus
Species: C. simoni
Binomial name
Cataulacus simoni
Emery, 1893

Cataulacus simoni P casent0280797.jpg

Cataulacus simoni D casent0280797.jpg

Specimen Label

Synonyms

Nothing is known about the biology of Cataulacus simoni.

Identification

A member of the granulatus group. The small size coupled with the relatively narrow head, large eyes and presence of clavate short hairs distinguishes the species from other members of the granulatus-group. The presence of clavate and subclavate hairs in some populations of Cataulacus granulatus from Java and the Andaman Islands is offset by size differences, differences in sculpturation, the presence of a constriction between mesonotum and propodeum and a marked difference in bodily build; Cataulacus simoni being a relatively slender species whilst granulatus is thick set and stocky. The female is distinguished from that of Cataulacus longinodus by the presence of clavate hairs on the alitrunk, especially the pronotum, and its smaller size. (Bolton 1974)

Keys including this Species

Distribution

Cataulacus simoni appears to be restricted to Sri Lanka and the Andaman Islands.

Distribution based on Regional Taxon Lists

Oriental Region: India, Sri Lanka (type locality).
Palaearctic Region: China.


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.

  • simoni. Cataulacus simoni Emery, 1893f: 248 (w.) SRI LANKA. Forel, 1909e: 393 (q.). Senior synonym of andamanensis: Bolton, 1974a: 72.
  • andamanensis. Cataulacus granulatus r. andamanensis Forel, 1903d: 406 (w.) INDIA (Andaman Is). Junior synonym of simoni: Bolton, 1974a: 72.

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 3.8 – 4.1, HL 0.90 – 1.00, HW 0.90 – 1.04, CI 100 - 104, EL 0.36 – 0.40, OI 38 - 40, IOD 0.68 – 0.76. SL 0.48 – 0.50, SI 46 - 53, PW 0.72 – 0.80, AL 0.92 – 0.98, MTL 0.46 – 0.52 (6 measured).

Bolton 1974 fig 38-41

Occipital crest complete or in some cases incomplete medially, armed with small denticles. Sides of head behind eyes minutely denticulate, terminating in a large denticle at the occipital corner. The head relatively long and narrow, with relatively large eyes. Lateral margins of alitrunk minutely denticulate along their length, the denticles spaced out and usually extending onto the lateral margins of the propodeal spines. Alitrunk broadest across the pronotum, the sides converging posteriorly in dorsal view; the alitrunk laterally without a pronounced U- or V-shaped notch or impression between the mesonotum and propodeum. Propodeal spines varying from a pair of distinct, relatively broad, short structures to a pair of small teeth. First gastral tergite not marginate laterally.

Head reticulate-rugose dorsally, the interspaces finely and quite feebly reticulate-punctate, dully shining. Pronotal dorsum reticulate-rugose, the points of intersection of the rugae often raised into minute peaks. On the mesonotum the rugae usually run longitudinally but in most specimens some feeble cross-meshes are visible which in some individuals may be strongly developed. Propodeal dorsum reticulate-rugose but more finely and densely so than the pronotum. The interspaces are always finely and weakly reticulate-punctate, dully shining. First gastral tergite reticulate-punctate with numerous weak longitudinal rugulae. The sides of the sclerite, above the tergosternal junction often have a number of coarse longitudinal rugae, but their development varies amongst individuals.

Dorsum of head with numerous short, distinctly and strongly clavate hairs which in some cases appear almost globular, with a short stem. Similar hairs are present upon the dorsal alitrunk but are more sparse, whilst upon the gaster the hairs are normal, short, thick, and blunt.

Queen

Bolton (1974) - TL 5.0, HL 1.02, HW 1.00, CI 98, EL 0.40, OI 40, IOD 0.78, SL 0.52, SI 52, PW 0.90, AL 1.40, MTL not measurable.

As worker but with reduced denticulation on the head and alitrunk. Propodeal spines proportionately smaller than in the worker, reduced to a pair of short, triangular teeth. Sculpturation and form and distribution of hairs as worker, but the mesoscutum and scutellum longitudinally rugose, more regularly so upon the former than the latter where the rugae are somewhat sinuate. Gaster very much longer than broad, the first tergite 1.70 long and 1.04 wide at maximum in the female examined.

Type Material

Bolton (1974):

Syntype workers, CEYLON: Kandy; Colombo, i.-ii.1892 (E. Simon) (probably in MCSN, Genoa).

Cataulacus granulatus race andamanensis Syntype workers, INDIA: Andaman Is. (MHN, Geneva) [examined].

References