Cardiocondyla emeryi

A tramp species that is common in anthropogenic habits in numerous tropical regions. Despite its large introduced range, it is an inconspicuous and little-noticed ant. Evidence suggests this species is native to Africa (Seifert, 2003), with its spread to other areas likely to have begun many hundreds of years ago.

Identification
A member of the Cardiocondyla emeryi group.

Seifert (2003) provides a key to the holoarctic species of Cardiocondyla (that includes this and other tropical tramp species) and states about emeryi: "The cosmopolitan population of Cardiocondyla emeryi shows extreme polymorphism in microsculpture clearly exceeding the usual intraspecific variability known for Cardiocondyla."

Distribution
A tramp species that is common in many tropical regions of the world.

Distribution based on Regional Taxon Lists
Afrotropical Region: Angola, Botswana, Cameroun, Cameroun, Comoros, Gambia, Ghana, Ivory Coast, Kenya, Mali, Mozambique, Nigeria, Rwanda, Saint Helena, Saudi Arabia, Socotra Archipelago, South Africa, Sudan, Uganda, United Arab Emirates, United Republic of Tanzania, Yemen, Zimbabwe. Australasian Region: Australia, New Caledonia, Norfolk Island. Indo-Australian Region: Borneo, Cook Islands, Fiji, French Polynesia, Hawaii, Indonesia, Malaysia, New Guinea, Niue, Samoa, Tonga, Wallis and Futuna Islands. Malagasy Region: Madagascar, Mauritius, Seychelles. Nearctic Region: United States. Neotropical Region: Anguilla, Aruba, Bahamas, Barbados, Bermuda, Brazil, British Virgin Islands, Costa Rica, Cuba, Dominican Republic, Ecuador, Galapagos Islands, Greater Antilles, Grenada, Guadeloupe, Haiti, Honduras, Lesser Antilles, Mexico, Netherlands Antilles, Puerto Rico, Turks and Caicos Islands. Oriental Region: Sri Lanka, Thailand, Vietnam. Palaearctic Region: Canary Islands, Egypt, Iran, Israel, Oman, Spain, Switzerland.

Biology
Creighton and Snelling (1974) provided natural history observations of Cardiocondyla emeryi colonies from La Feria, Texas. Creighton initially discovered foragers on a sidewalk of a cottage and, as a testament to the cryptic nature of the soil nest entrances of Cardiocondyla, was only able to locate colony's nest after months of searching. He reported "The entrance was a tiny, circular opening about one millimeter in diameter in the soil at the edge of the walk. Originally this entrance was completely concealed by a heavy overgrowth of grass." The colony was excavated and moved into an artificial nest. It was found to have numerous dealate queens. In maintaining the nest over more than a year it was found that workers readily accepted honey-dew, nectar and tissues and body fluids of other insects. Foraging and dietary observations of this captive colony and another free living nest observed for more than a year suggested the following:

"It appears that emeryi is omnivorous. It is probably predatory on small, soft-bodied insects and almost certainly scavenges the remains of larger ones. Solid food is rarely brought back to the nest and food transfer in the colony mainly involves regurgitated liquid foods."

"The foraging activities of the free colony showed a number of puzzling features. About the only clear-cut controlling factor was temperature, for foraging would not occur unless the surface temperature was 21 C or higher. Beyond this there was little to indicate what factors were involved in the foraging pattern. The foragers emerged singly from the nest entrance at widely separated intervals. Even under optimum conditions at least fifteen minutes intervened between the emergence of one worker and that of its follower. As a result, there was no concentration of foragers around the nest entrance, since the forager was well away from the nest entrance by the time the next one emerged from it. A secondary result was that no more than a dozen foragers (often less) were outside the nest at once."

Another interesting behavioral observation was the avoidance of larger and more dominant ant species (Solenopsis geminata and Pheidole dentata) when encountering C. emeryi workers. The emeryi foragers apparently produced an effective repellant pheromone as the other ant species would quickly scramble away from any encounter with these much smaller ants.

Wilson (1959) reported observing Tandem running in emeryi on two occasions in Puerto Rico. This foraging behavior was not found in the few colonies from Texas observed by Creighton (Creighton and Snelling 1974).

Heinze and Trenkle (1997) examined male polymorphism in this species. They collected ten colonies of Cardiocondyla emeryi in Bridgetown, Barbados. The nests were found under vegetation, ~ 5 cm deep in sand, and less than 30 m from the ocean. These nests were maintained in the laboratory by placing the ants in small plastic boxes with sand that they used to construct their nests. Food consisted of diluted honey and insect pieces.

These colonies produced several dozen winged (ergatoid) and wingless males over the course of a year. Ergatoid males clearly differed from workers in various characters such as more robust antennal scape, smaller eyes, and lighter coloration. Two additional males forms were also found with low frequency: gynandromorphs (half male, half queen) and ergatandromorphs (half male, half worker).

In colonies having a mixture of winged and wingless males there was typically a single ergatoid male with several winged males. Winged males showed no aggression towards one another or towards ergatoid males. Ergatoid males fought with newly eclosed ergatoid males, which was both observed directly and through finding maimed and dead individuals within a nest. Both winged and ergatoid males were observed mating with newly eclosed queens. In some cases these matings occurred in nests with both forms of males present.

Regional Notes
Espadaler (2007) - Canary Islands: This widespread tramp species was detected only at two seaside small towns, on poorly attended gardens.

Deyrup, Davis and Cover (2000) - In Florida this is a common species as far north as Bradford County. Nests are in ground in open areas, and very inconspicuous. The natural diet is hard to determine from watching individuals returning to the nest, because even dead insects are "mined" and brought back to the nest in the form of macerated tissue or fluids; this species is probably a general scavenger (Creighton and Snelling 1974). Workers are avoided by larger predatory ants such as Solenopsis geminata (Fabricius) (Creighton and Snelling 1974). Pest status: none. First published Florida record: Wheeler 1915.

Sharaf et al (2018) - Oman found in leaf litter where soil is dry.

Castes
Males may be winged or wingless (ergatoid).

More images beyond those shown in these galleries are found here.

Nomenclature

 *  emeryi. Cardiocondyla emeryi Forel, 1881: 5 (w.) VIRGIN IS. André, 1881b: 69 (m.); Forel, 1904f: 422 (q.); Emery, 1909a: 26 (m. ergatoid m., not q.); Arnold, 1916: 201 (q.). Senior synonym of nereis: Wilson & Taylor, 1967: 53; of monilicornis: Baroni Urbani, 1973: 200; of mahdii, mauritia, rasalamae: Bolton, 1982: 312. See also: Smith, M.R. 1944a: 33; Kugler, J. 1984: 3; Seifert, 2003a: 276. Current subspecies: nominal plus fezzanensis.
 * rasalamae. Cardiocondyla emeryi var. rasalamae Forel, 1891b: 161 (w.) MADAGASCAR. Forel, 1912k: 163 (q.). Junior synonym of emeryi: Bolton, 1982: 312.
 * mahdii. Cardiocondyla emeryi subsp. mahdii Karavaiev, 1911: 8 (w.) SUDAN. Finzi, 1936: 169 (q.m.). Junior synonym of emeryi: Bolton, 1982: 312.
 * monilicornis. Xenometra monilicornis Emery, 1917a: 96 (ergatoid m., not q.) VIRGIN IS. Junior synonym of emeryi: Baroni Urbani, 1973: 200.
 * nereis. Cardiocondyla nuda subsp. nereis Wheeler, W.M. 1927i: 140 (w.q.) AUSTRALIA. Junior synonym of emeryi: Wilson & Taylor, 1967: 53.
 * mauritia. Cardiocondyla mauritia Donisthorpe, 1946c: 776 (w.) MAURITIUS. Junior synonym of emeryi: Bolton, 1982: 312.

Worker
Seifert (2003) - Small size, CS 411. Head elongated, CL/CW 1.229. Scape short, SL/CS 0.758. Postocular index large, PoOc/CL 0.467. Eyes medium-sized, EYE 0.246. Frons very narrow, FRS/CS 0.215, frontal carinae immediately behind FRS level slightly converging and then diverging. Occipital margin more or less straight, with a suggested concavity. Whole head and mesosoma without longitudinal rugosity, except for small patches with weak carinulae mentioned below. Anterior clypeal margin with weak median concavity; central surface of clypeus in type specimens of C. emeryi with suggestions of flat foveolae, in type specimens of C. emeryi var. rasalamae with fine, interrupted fragments of carinulae and without any foveolae. Vertex in types of C. emeryi with deeply impressed, flat-bottomed foveolae of 17 - 19 µm diameter in densely-packed honey-comb arrangement; foveolae showing an inner corona (tubercle) of 8 -9 µm diameter (Fig. 58); median vertex with weak, interrupted longitudinal carinulae. Vertex in types of C. e. var. rasalamae in overall impression rather shining, structure and strength of sculpture radically different from that in types of C. emeryi (Fig. 59), showing shallow, but well-demarcated foveolae of 14 - 17 µm diameter, which occasionally possess an inner corona (tubercle); interspaces about as wide as foveolar diameter, much shining, with very fine cross-branched microcarinulae that may completely surround foveolae (= perifoveolar reticulum). Whole surface of mesosoma in types of C. emeryi with well-pronounced and dense microreticulum with meshes of 9 - 12 µm diameter; dorsal mesosoma additionally with scattered foveolae. Dorsal area of mesosoma in the types of C. emeryi var. rasalamae much less deeply sculptured than in C. emeryi types, moderately shining, with shallow foveolae similar to those on vertex; lateral area of mesosoma entirely reticulate but more delicately than in C. emeryi types. Petiole, except for the more smooth dorsal surface with well-pronounced and dense microreticulum that is weaker the C. emeryi var. rasalamae types. Postpetiole more smooth, with finer reticulum. Promesonotal dorsum showing in profile a continuous shallow convexity, not abruptly sloping into the moderately deep metanotal groove. In C. emeryi types, anterodorsal profile of propodeum convex, caudodorsal profile linear and slightly sloping downwards, spines deviating from longitudinal mesosomal axis by 40°. In C. e. var. rasalamae types, whole dorsal profile of propodeum very shallowly convex, not sloping downwards, spines less erect. Petiole node in dorsal view distinctly longer than wide; petiolar peduncle moderately long. Postpetiole in dorsal view wider than long, with shallowly concave anterior margin and evenly convex sides; postpetiolar sternite showing a conspicuous anteroventral prominence or bulge, without dents or carinae (Fig. 6). Different colour variants known: in most frequent variant whole body yellowish except for blackish gaster and terminal segment of antennal club; sometimes whole body dark or dirty brown. For morphometric data of 115 workers see Tab. 13.

Queen
Seifert (2003) - Very small size. Head elongated, CL/CW 1.180. Scape very short, SL/CS 0.731. Postocular index large, PoOc/CL 0.448. Occipital margin more or less straight. Anteromedian clypeal margin between level of frontal carinae straight to slightly concave. Frons very narrow, FRS/CS 0.216, frontal carinae in posterior part almost parallel. Vertex in the emeryi morph with deeply impressed, flat-bottomed foveolae of 16 - 17 µm diameter in densely-packed arrangement, foveolae showing an inner tubercle of 8 - 9 µm diameter; vertex sculpture in the rasalamae morph similar, but foveolar diameter a little smaller and arrangement less dense. Clypeus and narrow median stripe of anterior vertex frequently with short fragments of weak carinulae. Whole mesosoma without elements of longitudinal sculpture, except for 4 - 6 weak longitudinal carinae on lateral area of metapleuron. Whole dorsal area of mesosoma with deep, densely-packed foveolae; in the rasalamae morph foveolae less deep. Lateral area of mesosoma and petiolar peduncle reticulate. Petiole node foveolate, in dorsal view longer than wide, axis of petiolar peduncle deviating in lateral view from petiolar node axis by 45°. Spines well-developed, their axis deviating in lateral view by 18 - 30° from longitudinal mesosomal axis. Postpetiole with a strong anteroventral bulge, in dorsal view wider than long, with strongly convex sides, slightly concave anterior margin, and foveolate. Gaster tergites shining, but with very fine microreticulum. Colour bimorphism. Light form: lateral area of mesosoma, waist, and appendages yellowish; scutellum, gaster, and antennal club dark brown; remaining body parts yellowish brown. Dark form: whole body dark brown; coxae, femora, tibiae, scape, base of funiculus, and ventrolateral area of pronotum yellowish. For morphometric data of 12 gynes see Tab. 19.

Male
Andre (1881) described a male of the synonymous C. elegans and Emery (1909) described a C. emeryi ergatoid male.

Type Material


Seifert (2003) lists the following type material that he examined:
 * Cardiocondyla emeryi: 2 syntype workers labelled by Forel "Cardiocondyla Emeryi Forel Antilles St. Thomas (Forel)", MHN Genève.
 * C. emeryi var. rasalamae: 2 syntype workers labelled by Forel "C. emeryi Forel v. rasalamae Forel, Antananarivo Camboúe", MHN Genève. 1 syntype worker labelled by Forel "C. emeryi Forel v. rasalamae Forel, Antananarivo (Camboúe)" and by G. Mayr "Emeryi v. rasalamae Forel, Type", NHM Wien.
 * C. emeryi ssp. mahdii: 3 syntype workers labelled by Karavajev "Cardiocondyla mahdii sp.n. Karaw., Khartum 1900 W.K.", MHN Genève and NHM Basel.
 * C. nuda ssp. nereis: 4 syntype workers and 3 syntype gynes labelled "Norfolk I, A.M. Lea\Wm.M. Wheeler\M.C.Z. CoType 27887\subsp. nereis Wheeler", MCZ Cambridge.
 * C. mauritia: 1 type worker labelled "Mauritius 1941-45, 102, R. Mamel", "Pres. by Imp. Inst. Ent. B. M.1947-128", "Cardiocondyla mauritia H. Donisthorpe 1945 TYPE", BMNH London.