Cataulacus granulatus

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Cataulacus granulatus
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Crematogastrini
Genus: Cataulacus
Species: C. granulatus
Binomial name
Cataulacus granulatus
(Latreille, 1802)

Cataulacus granulatus P casent0217823.jpg

Cataulacus granulatus D casent0217823.jpg

Specimen Label

Synonyms

Despite being a widespread and common species, we know remarkably little about the biology of Cataulacus granulatus. Bingham (1903:121) encountered Cataulacus granulatus wandering about 'apparently in an aimless sort of way.' on the bark and leaves of trees. Their nests were made in hollow branches. An ergonomic or reproductive stage colony was found in a shoot of Saraca dives in Cuc Phuong National Park in North Vietnam (Eguchi and Bui 2007). In Vietnam they nest in living and dead twigs of trees and workers forage on vegetation (Eguchi et al. 2011).

Identification

A member of the granulatus group. One of the best features available for the recognition of the species is the relatively massive and coarsely sculptured petiole. When one has acquired an eye for the characters of this genus the general build and appearance of the segments of the pedicel in granulatus are unmistakable and are only likely to be confused with the very closely related marginatus, which is, however, separable on the structure of the first gastral tergite. (Bolton 1974)

Keys including this Species

Distribution

C. granulatus is the most widely distributed species of the genus in the Indo-Australian and Oriental regions and also appears to be the most common and most variable of the known forms. The species ranges from Nepal to Ceylon and through Thailand and Burma to Hainan Is., Borneo, Sumatra and Java. (Bolton 1974)

Known from Borneo, China, India, Indonesia (Java, Sumatra), Malaysia, Myanmar, Nepal, Thailand, Singapore, and Sri Lanka.

Distribution based on Regional Taxon Lists

Indo-Australian Region: Borneo, Indonesia, Malaysia, Singapore.
Oriental Region: Cambodia, India, Laos, Myanmar, Nepal, Sri Lanka, Thailand, Vietnam.
Palaearctic Region: China.

Distribution based on AntMaps

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Distribution based on AntWeb specimens

Check data from AntWeb

Abundance

Common

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)

Genetics

Polymorphic microsatellites have been identified for this species. (Debout et al. 2002)

Castes

Nomenclature

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

  • granulatus. Formica granulata Latreille, 1802c: 275, pl. 12, fig. 75 (w.) "GRAND INDES". Emery, 1893e: 215 (q.m.); Bingham, 1903: 123 (q.); Bolton, 1974a: 65 (m.). Combination in Cataulacus: Smith, F. 1853: 226. Senior synonym of hispidus: Bolton, 1974a: 64.
  • hispidus. Cataulacus hispidus Smith, F. 1876d: 611, pl. 11, fig. 11 (w.) SINGAPORE. Subspecies of granulatus: Forel, 1911a: 24; Viehmeyer, 1916a: 140. Junior synonym of granulatus: Bolton, 1974a: 64.

The following notes on F. Smith type specimens have been provided by Barry Bolton (details):

Cataulacus hispidus

Holotype worker in Oxford University Museum of Natural History. Labelled “Sing.”

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

Description

There is considerable variation in the length of the propodeal spines amongst the workers. Populations from Hainan Is. contain some individuals in which the spines are reduced to a pair of very small but acute teeth, and in some cases there are noticeable differences in spine length amongst members of the same series. Specimens from Java and the Andaman Is. have the hairs on the cephalic dorsum, and usually also the alitrunk, very small and somewhat clavate. In this condition the hairs resemble those found on the head of the female rather than the form usually associated with the worker caste. Sculpturation is variable in detail in the worker, as has been noted above. Usually it is the smaller individuals which possess the finer and looser rugoreticulum and more shining interspaces, but this does not by any means appear to be a hard and fast rule. (Bolton 1974)

Worker

Bolton (1974) - Bolton (1974) - TL 4.2 – 5.6, HL 1.06 – 1.30, HW 1.22 – 1.52, CI 105 - 120, EL 0.40 – 0.46, OI 27 - 33, IOD 0.90 – 1.20, SL 0.60 – 0.70, SI 45 - 49, PW 0.98 – 1.31, AL 1.16 – 1.50, MTL 0.60 – 0.77 (20 measured).

Bolton 1974 fig 1-6
Occipital crest usually weakened or incomplete medially, the lateral portions of the crest rather poorly defined in most specimens but equipped with a few denticles. Sides of head behind eyes denticulate, the occipital corner itself with a triangular tooth, decidedly larger than the denticles of the occiput or sides. Sides of alitrunk denticulate throughout their length, the denticles extending onto the lateral margins of the propodeal spines. Pronotum broad, the mesonotum narrowing posteriorly to a notch or impression separating it from the propodeum. Propodeal spines varying in length, may be reduced to a pair of small, acute teeth but are always widely separated, little divergent and shorter than half the distance separating the one from the other. Petiole in dorsal view massive, larger than the postpetiole, both segments broader than long, sometimes distinctly so. Subpetiolar process simple or with the posteroventral angle acute or dentiform, but never drawn out into a long, spur-like projection. In profile the anterior, dorsal and posterior faces of the petiole node forming a more or less continuous convexity so that the node is roughly dome-like. Sides of first gastral tergite not marginate. In dorsal view the basal portion of the sides is jagged or denticulate, the basal border itself is not.

Sculpturation of dorsum of head and alitrunk a rugoreticulum with reticulate-punctate interspaces, very variable in intensity, and the rugae with a tendency to assume a longitudinal direction upon the mesonotum and propodeal dorsum. The rugoreticulum varies from rather coarse, close set and flattened meshes to a very fine, loose organization in which the meshes are narrow and sharply defined. The interspaces are either finely and densely reticulate-punctate, more or less mat or dully shining, or the puncturation is quite superficial, leaving the interspaces shiny, First gastral tergite very finely reticulate-rugose with punctate interspaces and with a tendency towards reduction of the rugae in smaller individuals.

Erect hairs are present on all dorsal surfaces and around the margins of the head, alitrunk, pedicel and gaster and are numerous on the appendages. The hairs are usually short, broad and blunt, but in some populations those of the head and dorsal alitrunk may be very short and more or less clavate.

Queen

Bolton (1974) - TL 6.4 – 7.2, HL 1.40 – 1.56, HW 1.48 – 1.60, CI 102 - 107, EL 0.46 – 0.50, OI 29 - 31, IOD 1.16 – 1.30, SL 0.70 – 0.'78, SI 44 - 49, PW 1.38 – 1.50, AL 1.96 – 2.14, MTL 0.62 – 0.82 (13 measured).

Similar to worker, with denticulation reduced on sides of head behind eyes and on the lateral portions of the occipital crest. The denticulation of the sides of the pronotum distinct but reduced or even absent on the propodeal margins. Propodeal spines a pair of short teeth. Sculpturation of head and pronotum similar to worker but the rugae of the mesoscutum and scutellum longitudinal, with a few cross-meshes. First gastral tergite usually with a distinct rugoreticulum on the basal quarter of its length which fades out posteriorly to a few weak, longitudinal rugulae. The entire surface finely and densely reticulate-punctate. Distribution of erect hairs as in worker but they are proportionately shorter in the present caste. Those upon the dorsum of the head (but not the margins) appear always to be very short and inconspicuous, and are often clavate or stud-like, even in populations in which the hairs are normal in the workers.

Male

Bolton (1974) - TL 4.8 – 5.4, HL 0.96 – 1.08, HW 1.10 – 1.24, CI 107 - 114, EL 0.36 – 0.40, OI 32 - 35, IOD 0.86 – 0.94, SL 0.56 – 0.64, SI 50 - 52, PW 0.92 – 1.04, AL 1.49 – 1.74, MTL 0.72 – 0.76 (5 measured).

Occipital crest incomplete medially, laterally with only one or two denticles. Sides of head behind eyes denticulate, the occipital corner with a triangular, short tooth. Lateral margins of pronotum and propodeum weakly denticulate, the propodeum with a pair of small teeth. Anterior arms of notauli developed and cross-ribbed, the posterior arm usually represented by a broad, shallow, longitudinal impression, more rarely by a distinct groove. Parapsidal furrows poorly defined, inconspicuous. Sculpturation of dorsum of head a fine loose rugoreticulum with reticulate-punctate interspaces. On the alitrunk the sculpturation is variable. Pronotum sculptured as head but the reticulum more dense; this may extend onto the mesoscutum, scutellum and propodeal dorsum but usually the cross-meshes tend to disappear, leaving these areas longitudinally rugose. Pedicel reticulate-rugose with punctate interspaces, often with the longitudinal rugae predominant. Gaster everywhere finely and densely reticulate-punctate with basigastric costulae usually present. Erect hairs present on all dorsal surfaces of head and body, simple and blunt, relatively long.

Type Material

Bolton (1974):

Formica granulate Holotype worker, 'GRAND-INDES' (location of type not known).

Cataulacus hispidus Holotype worker, SINGAPORE (UM, Oxford) [examined].

References