Cataulacus

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Cataulacus
Cataulacus lujae
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Crematogastrini
Genus: Cataulacus
Smith, F., 1853
Type species
Cataulacus taprobanae
Diversity
65 species
3 fossil species
(Species Checklist)

Cataulacus lujae casent0178289 profile 1.jpg

Cataulacus lujae

Cataulacus lujae casent0178289 dorsal 1.jpg

Specimen Label

Synonyms

The genus is Palaeotropical with its main diversity centred in the Afrotropical region. The taxonomy of the genus is in a fairly good condition since it was first revised by Bolton (1974a) on a global scale, additional species added later by Snelling (1979) for the Afrotropical region and then Bolton (1982) presented an updated revision with more new species and a species-level key. Most species of this genus are forest-inhabitants while only a minority live in more open and arid habitats. All nest and forage on trees or in the vegetation and several species are known to be trophobiotic, while one species was observed to prey on termites (Arnold, 1917; Bolton, 1974a). Interestingly, many members of this genus often co-occur with more dominant and aggressive ant species from the genera Crematogaster and Oecophylla but are usually well-protected by their heavily armoured exterior or dropping-off behaviour (Bolton, 1974a; Yanoviak et al., 2008).

Identification

Bolton's (1974) - Monomorphic, arboreal myrmicine ants with the head and usually also the body somewhat depressed. Antennae 11-segmented with a 3-segmented club. Palp formula 5,3. Anterior clypeal margin usually notched or impressed medially. Frontal carinae very widely separated, strongly expanded. Antennal scrobes present, running below the large eyes, bounded by the frontal carinae only anterodorsally. First gastral tergite very much enlarged, constituting the entire dorsal gaster in female and worker and the greater portion of the dorsum in the male. Wings always with r-m and m-cu absent, and with M fused to Rs until close to 2r. Male genitalia partially retractile, with cuspis of volsella absent, digitus strongly developed into a broadly T-shaped structure; aedeagus serrate or denticulate ventrally.

Keys including this Genus

Keys to Species in this Genus

Species Groups

Cataulacus species groups

Distribution

Bolton (1974) - The main centres of speciation are the Ethiopian region, particularly the rain forest zones, and the Indonesian and Philippine islands in the Indo-Australian region. Madagascar shares a single species with southern Africa and this and some of its remaining species are members of the now dominant species-group of eastern and southern Africa, the intrudens (F. Smith) group. The rest of the Madagascan fauna is, however, very specialized and not of the intrudens-group. In fact these species are related to huberi E. Andre and its allies, a group predominantly of the West and Central African rain forests. This apparently indicates a double migration of species in the direction Africa → Madagascar, the first consisting of huberi-group species and the second and later migration of intrudens-group forms.

The Indian subcontinent is very poorly populated at species level, only 3 being known, and with a fourth present on Ceylon and the Andaman Islands. Only a single species, granulatus (Latreille), is known to occur in both the Oriental and Indo-Australian regions. The most easterly record of the genus is from Waigeo Is., off north-west New Guinea (Irian Barat), and a marked decrease in the number of species occurs along the Indonesian islands in a west-east direction. The fossil species are known mostly from areas now well outside the range of the genus, namely southern and eastern Europe, and indicate a much wider distribution for the genus during Tertiary times.

World distribution based on political regions. View/Edit Data
Cataulacus Distribution.png Worlddistribution legend.jpg

Species richness

Species richness by country based on regional taxon lists (countries with darker colours are more species-rich). View Data

Cataulacus Species Richness.png

Abundance

At no point in its range can any species of Cataulacus be considered dominant over other arboreal ant genera, nor are they known to be abundant in absolute numbers over wide areas, but certain species are noticeably much more common within their range than others and where such species occur they may constitute a good proportion of the arboreal ant fauna and are usually quite conspicuous. In this last category may be placed Cataulacus guineensis of the West and Central African forests, Cataulacus intrudens of southern and eastern Africa and Cataulacus granulatus of the Oriental and Indo-Australian regions. (Bolton 1974)

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

Monomorphic workers.

Morphology

Worker Morphology

 • Antennal segment count 11 • Antennal club 3 • Palp formula 5,3 • Total dental count 3-8 • Spur formula 0, 0 • Eyes present • Scrobes absent • Sting present

Nomenclature

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

  • CATAULACUS [Myrmicinae: Cataulacini]
    • Cataulacus Smith, F. 1853: 225. Type-species: Cataulacus taprobanae, by subsequent designation of Bingham, 1903: 120.
    • Cataulacus senior synonym of Otomyrmex: Wheeler, W.M. 1922a: 664; Bolton, 1974a: 1.
  • OTOMYRMEX [junior synonym of Cataulacus]
    • Otomyrmex Forel, 1891b: 147 [as subgenus of Cataulacus]. Type-species: Cataulacus oberthueri, by monotypy.
    • Otomyrmex junior synonym of Cataulacus: Wheeler, W.M. 1922a: 664; Bolton, 1974a: 7.

Description

Worker

Bolton (1974) - Minute to large (TL 2.7 – 11.0), mostly black myrmicine ants; monomorphic although often with a considerable size-range within the species, and with the head and body somewhat dorsoventrally flattened.

Mandibles with 1 to 3 apically situated teeth followed by a row of small to minute denticles or by an unarmed apical (masticatory) margin. Palp formula maxillary 5, labial 3-segmented. Clypeus large, rounded behind, usually notched or with an arcuate impression anteromedially and with the anterolateral corners acute or dentate. Clypeal suture often reduced or faint but rarely completely absent. Frontal carinae widely separated, strongly expanded laterally, reaching almost or quite to the level of the eye where they are almost invariably produced into a preocular tooth. The frontal carinae usually overhang the sides of the head of front of the eye and form the apparent lateral margins of the head in front of the eye in full-face view. Antennal scrobes present, running below the eyes and capable of accommodating the whole antenna. Anteriorly the scrobes are bounded above by the frontal carinae but below and behind the eyes the scrobal margins are constituted of the side wall of the head capsule. Scrobes often bounded below by a carina which terminates in a ventrally-directed tooth posteriorly. Antennae 11-segmented, the three apical funicular segments forming a club. Scape curved and much thicker apically than basally. The eyes are distinct, usually large or very large; ocelli are absent (except in some individuals of latus). Alitrunk usually marginate laterally at least on the pronotum (faint in oberthueri, absent from insularis), the margination often equipped with denticles, spines, teeth or lobiform prominences. Dorsal alitrunk often without sutures but the promesonotal suture may be marked by a faint line or impression. Sutures visible laterally upon the alitrunk; a transverse suture on the mesepisternum nearly always evident. Mesokatepisternum with the anteroventral corner produced into a spine, tooth or tubercle, rarely only an acute angle. Propodeum usually bispinose, more rarely bidentate, unarmed in one species (inermis); metapleurallobes or teeth present at the base of the propodeal declivity. Legs with the femora usually grooved or bicarinate beneath to receive the tibiae. Petiole sessile, with a distinct ventral process; in some species the postpetiole also with such a process. First gastral tergite greatly expanded, comprising the whole of the dorsum of the gaster in dorsal view. First sternite also much enlarged, the remaining segments very reduced, visible apically and apicoventrally. Sting reduced or vestigial, apparently non-functional. Hairs in the species are typically short, broad and blunt but variously specialized in some species, absent in others; almost invariably with 3 to 4 long bristles projecting from the lower border of the eye. Full adult coloration uniform black or black-brown, commonly with the antennae, tibiae and tarsi lighter, yellow or yellow-brown.

Queen

Bolton (1974) - Similar to the worker but the head always with ocelli developed, the alitrunk with flight sclerites and with well-marked dorsal sutures. Gaster usually more elongate than in the worker and often with virtually parallel lateral borders.

Male

Bolton (1974) - Head constructed basically as in worker but with ocelli present. The frontal carinae are not so strongly expanded laterally and in some species the sides of the head proper are visible below the carinae when in dorsal view. Preocular teeth often absent. The head capsule itself is strongly narrowed in front of the large, very prominent eyes. Pronotum well developed, clearly visible in dorsal view and not at all overhung by the mesoscutum. Parapsidal furrows present. Notauli usually with the anterior arms of the Y-shape developed and crossribbed; the posterior arm often little or not developed, rarely as well developed as the anterior arms. Venation as in the female. Propodeum bidentate or bispinose; the petiole and sometimes also the postpetiole more elongate and slender than in the female or worker castes but the ventral processes similarly developed. First gastral tergite very large but not as strongly developed as in the other castes; the following segments usually visible in dorsal view. Genitalia partially retractile, but the highly sclerotized apical portions of the parameres always projecting. In species examined the genitalia had the aedeagus at least strongly serrate ventrally, usually denticulate; volsellae with cuspis absent and the digitus developed into a much enlarged, broadly T-shaped lamelliform structure. The basal portion of each paramere is much less strongly sclerotized than the apical, projecting portion, the latter usually with numerous fine hairs.

Immature Stages

Larva. G. C. Wheeler & J. Wheeler (1960) - body profile elongate-subelliptical, with the head applied to the ventral surface near the anterior end. Under this grouping the Cataulacus larvae were given as cataulaciform; with the body profile straight, elongate-subelliptical; prothorax forming a very short, stout neck which is inclined ventrally to 45 degrees; segmentation indistinct. The mandibles were also described as cataulaciform: roughly trapezium-shaped, the apex forming a slender, short acute tooth which is curved medially; subapical portion of medial border more or less projecting and bearing 2 to 5 minute teeth.

Pupa. Free, not enclosed in cocoons.

References

  • Arnold, G. 1917. A monograph of the Formicidae of South Africa. Part III. Myrmicinae. Ann. S. Afr. Mus. 14: 271-402 (page 386, Cataulacus in Myrmicinae, Cataulacini)
  • Ashmead, W. H. 1905c. A skeleton of a new arrangement of the families, subfamilies, tribes and genera of the ants, or the superfamily Formicoidea. Can. Entomol. 37: 381-384 (page 384, Cataulacus in Cryptoceridae, Cataulacinae)
  • Bingham, C. T. 1903. The fauna of British India, including Ceylon and Burma. Hymenoptera, Vol. II. Ants and Cuckoo-wasps. London: Taylor and Francis, 506 pp. (page 120, Type-species: Cataulacus taprobane; by subsequent designation)
  • Bolton, B. 1974a. A revision of the Palaeotropical arboreal ant genus Cataulacus F. Smith (Hymenoptera: Formicidae). Bull. Br. Mus. (Nat. Hist.) Entomol. 30: 1-105 (page 1, Cataulacus senior synonym of Otomyrmex; and revision of genus)
  • Bolton, B. 1982. Afrotropical species of the myrmecine ant genera Cardiocondyla, Leptothorax, Melissotarsus, Messor and Cataulacus (Formicidae). Bulletin of the British Museum (Natural History). Entomology, 46: 307-370 (page 354, Key to Afrotropical species)
  • Bolton, B. 2003. Synopsis and Classification of Formicidae. Mem. Am. Entomol. Inst. 71: 370pp (page 193, Cataulacus in Myrmicinae, Cataulacini)
  • Dalla Torre, K. W. von. 1893. Catalogus Hymenopterorum hucusque descriptorum systematicus et synonymicus. Vol. 7. Formicidae (Heterogyna). Leipzig: W. Engelmann, 289 pp. (page 137, Cataulacus in Myrmicinae)
  • Emery, C. 1877b. Saggio di un ordinamento naturale dei Mirmicidei, e considerazioni sulla filogenesi delle formiche. Bull. Soc. Entomol. Ital. 9: 67-83 (page 81, Cataulacus in Myrmicidae, Cryptoceridae)
  • Emery, C. 1895l. Die Gattung Dorylus Fab. und die systematische Eintheilung der Formiciden. Zool. Jahrb. Abt. Syst. Geogr. Biol. Tiere 8: 685-778 (page 771, Cataulacus in Myrmicinae, Cataulacini)
  • Emery, C. 1914e. Intorno alla classificazione dei Myrmicinae. Rend. Sess. R. Accad. Sci. Ist. Bologna Cl. Sci. Fis. (n.s.) 18: 29-42 (page 42, Cataulacus in Myrmicinae, Cataulacini)
  • Forel, A. 1892d. Attini und Cryptocerini. Zwei neue Apterostigma-Arten. Mitt. Schweiz. Entomol. Ges. 8: 344-349 (page 344, Cataulacus in Myrmicinae, Dacetini)
  • Forel, A. 1893b. Sur la classification de la famille des Formicides, avec remarques synonymiques. Ann. Soc. Entomol. Belg. 37: 161-167 (page 164, Cataulacus in Myrmicinae, Dacetini)
  • Forel, A. 1917. Cadre synoptique actuel de la faune universelle des fourmis. Bull. Soc. Vaudoise Sci. Nat. 51: 229-253 (page 246, Cataulacus in Myrmicinae, Cataulacini)
  • Mayr, G. 1865. Formicidae. In: Reise der Österreichischen Fregatte "Novara" um die Erde in den Jahren 1857, 1858, 1859. Zoologischer Theil. Bd. II. Abt. 1. Wien: K. Gerold's Sohn, 119 pp. (page 26, Cataulacus in Myrmicinae [Myrmicidae])
  • Smith, F. 1853 [1854]. Monograph of the genus Cryptocerus, belonging to the group Cryptoceridae - family Myrmicidae - division Hymenoptera Heterogyna. Trans. Entomol. Soc. Lond. (2) 2: 213-228 (page 225, Cataulacus in Myrmicidae, Cryptoceridae)
  • Smith, F. 1857a. Catalogue of the hymenopterous insects collected at Sarawak, Borneo; Mount Ophir, Malacca; and at Singapore, by A. R. Wallace. [part]. J. Proc. Linn. Soc. Lond. Zool. 2: 42-88 (page 80, Cataulacus in Formicidae, Cryptoceridae)
  • Smith, F. 1858a. Catalogue of hymenopterous insects in the collection of the British Museum. Part VI. Formicidae. London: British Museum, 216 pp. (page 195, Cataulacus in Poneridae, Cryptoceridae)
  • Smith, F. 1862a. Catalogue of hymenopterous insects collected by Mr. A. R. Wallace in the islands of Ceram, Celebes, Ternate, and Gilolo. [concl.]. J. Proc. Linn. Soc. Lond. Zool. 6: 49-66 (page 49, Cataulacus in Cryptoceridae)
  • Smith, F. 1862d. A list of the genera and species belonging to the family Cryptoceridae, with descriptions of new species; also a list of the species of the genus Echinopla. Trans. Entomol. Soc. Lond. (3) 1: 407-416 (page 414, Cataulacus in Formicidae, Cryptoceridae)
  • Smith, F. 1871a. A catalogue of the Aculeate Hymenoptera and Ichneumonidae of India and the Eastern Archipelago. With introductory remarks by A. R. Wallace. [part]. J. Linn. Soc. Lond. Zool. 11: 285-348 (page 334, Cataulacus in Cryptoceridae)
  • Smith, F. 1876d. Descriptions of new species of Cryptoceridae, belonging to the genera Cryptocerus, Meranoplus, and Cataulacus. Trans. Entomol. Soc. Lond. 1876: 603-612 (page 609, Cataulacus in Cryptoceridae)
  • Wheeler, W. M. 1910b. Ants: their structure, development and behavior. New York: Columbia University Press, xxv + 663 pp. (page 142, Cataulacus in Myrmicinae, Cataulacini)
  • Wheeler, W. M. 1922i. Ants of the American Museum Congo expedition. A contribution to the myrmecology of Africa. VII. Keys to the genera and subgenera of ants. Bull. Am. Mus. Nat. Hist. 45: 631-710 (page 664, 665, Cataulacus senior synonym of Otomyrmex; Cataulacus in Myrmicinae, Cataulacini)
  • Yanoviak, S. P., R. Dudley, and M. Kaspari. 2005. Directed aerial descent in canopy ants. Nature. 433:624-626.
  • Yanoviak, S. P., B. L. Fisher, and A. Alonso. 2007. Arboreal ant diversity (Hymenoptera: Formicidae) in a central African forest. African Journal of Ecology. 46:60-66.
  • Yanoviak, S. P., B. L. Fisher, and A. Alonso. 2008. Directed aerial descent behavior in African canopy ants (Hymenoptera: Formicidae). Journal of Insect Behavior. 21:164-171.