Cataulacus nenassus

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

Cataulacus nenassus P casent0900258.jpg

Cataulacus nenassus D casent0900258.jpg

Specimen Label

Apart from the fact that the species inhabits teak forests nothing is known about its biology.

Identification

A member of the granulatus group. This species is very closely related to Cataulacus setosus but may immediately be separated from it by the nature of the gastral sculpture in both worker and female. Also, in the Cataulacus nenassus worker the alitrunk is proportionately narrower and longer (width to length ratio 1 to 1.3 or 1.4) than in setosus which has a width to length ratio of about 1 to 1.1. The head is also narrower, the range of cephalic indices recorded in the type-series being 100 - 105 as compared to a range of 109 - 111 in setosus workers. (Bolton 1974)

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Indo-Australian Region: Indonesia (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.

  • nenassus. Cataulacus nenassus Bolton, 1974a: 70, fig. 41 (w.q.m.) INDONESIA (Java).

Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.

Description

Worker

Holotype. TL 4.8, HL 1.16, HW 1.18, CI 101, EL 0.42, OI 35, IOD 0.90, SL 0.62, SI 53, PW 0.94, AL 1.30, MTL 0.61.

Bolton 1974 fig 38-41
Occipital crest complete, shallowly concave in full-face view and denticulate throughout its length, the lateral denticles larger than those situated more mesad. Sides of head behind eyes denticulate, terminating in a small tooth at the occipital corners. Pronotal margins with four or five relatively large denticles and one or two smaller; mesonotal margins with two denticles, the sides of the propodeum and outer margins of the spines with numerous small or minute dentic1es. Propodeal spines long and strong, divergent, relatively close set basally. Petiole in profile with the anterior face steeply sloping, the dorsal and posterior faces continuous. First gastral tergite not marginate but with a few small denticles laterally towards the base.

Dorsum of head reticulate-rugose, the interspaces dully shining, finely and densely but shallowly reticulate-punctate. Dorsal alitrunk similarly sculptured but with the rather flattened longitudinal rugae tending to predominate. Propodeal declivity with a few faint, transverse rugae. Nodes of petiole and postpetiole similarly but rather more coarsely sculptured than the alitrunk, the points of intersection of the rugae raised into peaks (best seen in profile). First gastral tergite finely reticulate-punctate, with a fine but distinct, predominantly longitudinal rugulation covering the entire surface of the sclerite.

Short, erect, blunt hairs numerous upon all dorsal surfaces of the head and body, and also upon the appendages.

Paratype. TL 4.8 – 5.1, HL 1.16 – 1.20, HW 1.20 – 1.22, CI 100 - 105, EL 0.40 – 0.42, OI 32 - 35, IOD 0.90 – 0.92, SL 0.58 – 0.64, SI 48 - 53, PW 0.98 – 1.00, AL 1.30 – 1.36, MTL 0.60 – 0.66 (6 measured).

As holotype but with the number of large denticles on the pronotal margins variable, with a maximum of seven in the specimens available.

Queen

Paratype. TL 5.8 – 6.2, HL 1.24 – 1.30, HW 1.24 – 1.30, CI 100, EL 0.44 – 0.46, OI 34 - 35, IOD 0.96 – 1.00, SL ca 0.68, SI 52 - 53, PW 1.10 – 1.19, AL 1.68 – 1.78, MTL 0.68 – 0.70 (5 measured).

As worker but with denticulation of occipital crest and sides of head behind eyes reduced. Sides of pronotum with four or five weak denticles; sides of propodeum irregular but not markedly denticulate. Propodeal spines shorter but distinct. Sculpturation of head, pronotum, pedicel and gaster similar to but rather more coarse than in the worker. Mesoscutum strongly longitudinally rugose, as is the propodeum. Scutellum similar but with some distinct crossmeshes, and without a transverse groove dividing it into anterior and posterior portions.

Male

Paratype. TL ca 5.2, HL 1.00 – 1.04, HW 1.02 – 1.10, CI 102 - 106, EL 0.40 – 0.42, OI 38 - 39, IOD 0.80 – 0.84, SL 0.62 – 0.64, SI 56 - 58, PW 0.92 – 0.98, AL 1.56 -1.64 (2 measured). Occipital crest complete and denticulate; sides of head behind eyes denticulate, terminating in a short, triangular tooth at the occipital corners. Sides of pronotum strongly marginate and denticulate. Sides of propodeum unarmed, the spines short but distinct. Anterior arms of notauli well developed and cross-ribbed, the posterior arm broad and shallowly demarcated. Head longitudinally rugose with a few cross-meshes, the rugae in one specimen tending to arch posteriorly and become transverse behind the ocelli. Pronotum sharply reticulate-rugose with punctate interspaces, as are the scutellum and propodeal dorsum, but the scutum is predominantly longitudinally rugose. Gaster very finely and faintly reticulate-punctate with numerous fine basigastric costulae, and some extremely fine longitudinal rugulae on the lateral portions of the tergite. All dorsal surfaces of head, body and appendages with numerous hairs.

Paratype Specimen Labels

Type Material

Holotype worker, JAVA: Semarang, no. g45, 7.ii.I928 (L. G. E. Kalshoven) (MCZ, Boston).

Paratypes. 9 workers, same data as above; one pin, bearing three specimens, has a second label which repeats the data of the first and adds 'Teak Forest' (BMNH; MCZ, Boston; USNM, Washington). 6 alate females, same data as holotype (MCZ, Boston; BMNH). 1 alate female, 'Java zee', 11.ix.1920 (Kl. Kombuis) (MCZ, Boston). 2 males, same data as holotype (MCZ, Boston; BMNH).

References