Cardiocondyla

Cardiocondyla are tiny myrmicine ants which live in colonies consisting of several dozen to a few hundred workers. Queen number varies by species. Nests are commonly in the soil, less so under rocks and in just a few species are known to be made in vegetation. Open arid habitats are favored by many Cardiocondyla. Several species are well known tramp species (Seifert, 2003).

Identification
Bolton (1982) - Small to minute monomorphic myrmicine ants. Mandibles with 5 teeth which decrease in size from apical to basal. Palp formula 5, 3 (16 species examined). Clypeus with flattened and prominent projecting lateral portions which are fused to the raised projecting median portion to form a shelf which projects forward over the mandibles. Sometimes the lateral portions of the clypeus extend further forward than the median so that the anterior margin of the projecting shelf is concave medially. Median portion of clypeus posteriorly broadly inserted between small narrow frontal lobes. Frontal carinae and antennal scrobes absent. Eyes present, generally large and conspicuous, situated in front of the midlength of the sides. Antennae with 11-12 segments, usually with a distinct 3-segmented club but the first club segment may be relatively small. Promesonotal dorsum flattened to evenly convex in profile, the dorsal alitrunk without sutures but the metanotal groove commonly (but by no means universally) impressed. Pronotal corners in dorsal view broadly rounded to bluntly angular and projecting. Propodeal spiracle small, situated approximately at the midlength, often low down on the side but not shifted back towards the margin of the declivity. Propodeum unarmed to strongly bispinose. Metapleurallobes low and rounded. Petiole nodiform with a moderate to long, usually slender, anterior peduncle. Postpetiole dorsoventrally flattened in profile, in dorsal view very broad, much broader than the petiole node. Sting large and strongly developed, knife blade-like and broad in profile, without lamelliform appendages. Dorsal surfaces of body usually hairless.

Cardiocondyla is still separated from Leptothorax and its close relatives by the characters devised by Emery and Wheeler, namely the specialized form of the anterior clypeus (although this is hinted at in some Leptothorax), the characteristic form of the postpetiole and the reduced wing venation of the females. A further character distinguishing the two is the specialized blade-like sting of Cardiocondyla, not seen in Leptothorax.

Eguchi, Bui and Yamane (2011) - Worker monomorphic; head in full-face view subrectangular; frontal lobe small and narrow; frontal carina and antennal scrobe absent; median portion of clypeus prominently extended forward, and fused to the flattened lateral portions to form a shelf which hides basal part of mandibles in full-face view but is elevated away from the dorsal surface of mandibles in lateral view; posteromedian portion of clypeus relatively broadly inserted between frontal lobes; median clypeal seta present; mandible triangular, with 5 teeth which decrease in size from apex to base; palp formula 5,3; stipes of maxilla with a transverse crest at about midlength; antenna 12-segmented, with 3-segmented club; eye generally large and conspicuous; promesonotal dorsum in lateral view flattened to slightly convex;promesonotal suture absent dorsally; metanotal groove absent or distinctly impressed dorsally; propodeum nearly unarmed to strongly bispinose; propodeal lobe roundly extended posteriad; petiole pedunculate anteriorly and with distinct node; subpetiolar process present but small; postpetiole in lateral view dorsoventrally flattened, in dorsal view very broad, much broader than petiolar node; gastral shoulder indistinct or distinct; dorsa of head, mesosma, waist and gaster lacking standing hairs.

The worker of Cardiocondyla is similar to Monomorium and Temnothorax, but in the latter two genera the postpetiole is as broad as or only a little broader than the petiolar node, and the dorsa of head, mesosoma, waist and gaster bear at least a few standing hairs.

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



Biology
The biology of most Cardiocondyla species has not been studied. Seifert revised the holarctic species of Cardiocondyla in 2003 and the following synopsis is based on his excellent treatment of the genus. References to other publications and more details about what is reported here can be found in Seifert (2003).

Many Cardiocondyla species inhabit areas that experience frequent disturbance and/or are quite open. These may be human altered areas, where a number of Cardiocondyla tramp species thrive, but also natural areas such as semi deserts and steppes, immature soils at rivers, lakes, and sea shores and to a lesser extent forest margins or burned-down woodland patches. In contrast to this open-land group, the natural habitat affinities of many tropical species are primary rain forests.

Nests are typically in soil and sometimes under stones. Two species are known to nest in vegetation but this is unusual for the genus. The single nest entrances is small (1-1.5 mm) and inconspicuous. In the desert nests can be relatively deep (> 1m) and have many chambers but in areas where conditions are less extreme there is generally a single chamber (15-20 mm diameter and 3-4 mm height) that is not far below the ground surface (2-15 cm).

Cardiocondyla tramp species (Cardiocondyla wroughtonii, Cardiocondyla obscurior, Cardiocondyla mauritanica, Cardiocondyla emeryi and Cardiocondyla minutior) are known to be polygynous, as are some less widespread species, while other species are known to be monogynous.

Cardiocondyla ants are omnivorous. Zoophagy (zoo necrophagy and killing of small weakly sclerotised arthropods), granivory, and nectarivory have also been noted. Tandem running has been observed as a method of recruitment to food sources in a few species.

Intranidal mating appears to be the norm for most species in the genus. Mating strategies are species dependent and may take various forms. Winged males may mate within their nest or fly to and enter other colonies to mate. Queen mate intranidally and fly from their nest to begin a new colony, become integrated into their natal colony, or may walk away from their nest and establish a new colony nearby.

Cardiocondyla are unusual in having peculiar male forms. Male polymorphism is found in some species with typical males and an ergatoid form. These latter males are wingless and worker like in appearance. Ergatoid males fight with other males within their natal nest. By killing potential rival males a dominant male can monopolize matings with the virgin queens in their colony. Morphological modifications that enhance the fighting abilities of ergatoid males have been documented, e.g., modified mandibles well suited to fighting and increased mesosomal size for better protection against attacks from rivals. Another unusual characteristic of ergatoid males is the continuation of spermatogenesis throughout their adult life. Males of most aculeate hymenoptera stop producing sperm once they are fully mature.

Some species are known to produce different queen morphs. This presumably facilitates there being a longer range dispersal queen form and a shorter or non-dispersing form. Gyne polymorphism appears to be an adaptation for species inhabiting continental desert or semi-desert habitats. The cosmopolitan tramp species, on the other hand, do not exhibit this gyne polymorphism.

Castes
Ergatoid males and queens are present in some species.

Nomenclature

 *  CARDIOCONDYLA [Myrmicinae: Formicoxenini]
 * Cardiocondyla Emery, 1869b: 20. Type-species: Cardiocondyla elegans, by monotypy.
 * Cardiocondyla senior synonym of Emeryia: Forel, 1892h: 461; Forel, 1892i: 313.
 * Cardiocondyla senior synonym of Xenometra: Baroni Urbani, 1973: 200; Marikovsky & Yakushin, 1974: 60.
 * Cardiocondyla senior synonym of Dyclona, Loncyda, Prosopidris: Smith, D.R. 1979: 1375; Bolton, 1982: 309.
 * DYCLONA [junior synonym of Cardiocondyla]
 * Dyclona Santschi, 1930b: 70 (footnote) [as subgenus of Cardiocondyla]. Type-species: Monomorium cristatum, by original designation.
 * Dyclona junior synonym of Cardiocondyla: Bolton, 1982: 309.
 * EMERYIA [junior synonym of Cardiocondyla]
 * Emeryia Forel, 1890b: cx. Type-species: Emeryia wroughtonii, by monotypy.
 * Emeryia junior synonym of Cardiocondyla: Forel, 1892h: 461; Forel, 1892i: 313.
 * LONCYDA [junior synonym of Cardiocondyla]
 * Loncyda Santschi, 1930b: 70 [as subgenus of Cardiocondyla]. Type-species: Cardiocondyla (Loncyda) monardi, by monotypy.
 * Loncyda junior synonym of Cardiocondyla: Bolton, 1982: 309.
 * PROSOPIDRIS [junior synonym of Cardiocondyla]
 * Prosopidris Wheeler, W.M. 1935b: 40 [as subgenus of Cardiocondyla]. Type-species: Cardiocondyla (Prosopidris) sima, by original designation.
 * Prosopidris raised to genus: Reiskind, 1965: 80.
 * Prosopidris junior synonym of Cardiocondyla: Bolton, 1982: 309.
 * XENOMETRA [junior synonym of Cardiocondyla]
 * Xenometra Emery, 1917a: 96. Type-species: Xenometra monilicornis (junior synonym of Cardiocondyla emeryi), by monotypy.
 * Xenometra junior synonym of Cardiocondyla: Baroni Urbani, 1973: 199; Marikovsky & Yakushin, 1974: 60.

Eguchi, Bui and Yamane (2011) - The Afrotropical species were revised by Bolton (1982), and the elegans-, bulgarica-, batesii-, nuda-, shuckardi-, stambuloffii-, wroughtonii-, emeryi- and minutior-groups were revised by Seifert (2003). Workers of Vietnamese species have the following features.