Worker minute, smooth, almost hairless. Clypeus projecting over the bases of the mandibles, steep in front, with rounded anterior border. Frontal area strongly impressed. Frontal carinae short and straight. Eyes well developed; ocelli lacking. Mandibles broad, triangular, dentate. Antennae 12-jointed, with long first funicular joint and 3-jointed club, the last joint very large. Promesonotal suture indistinct; mesoepinotal constriction well developed. Epinotum armed with spines or teeth. Petiole with long peduncle and small, rounded node. Postpetiole conspicuously large, cordate or transversely elliptical. Gaster formed in large part by the first segment.
Female winged (except in C. emeryi Forel), somewhat larger than the worker; head of the same shape but with ocelli. Pronotum not covered by the mesoscutum in front. Petiole and postpetiole usually broader than in the worker. Wings with reduced venation; pterostigma near the middle of the costal border; one closed cubital cell; distal portions of radius and cubitus obsolete; brachius not developed beyond the nervulus but bending up into the submedius. According to Emery, the female of C. emeryi is wingless and has the posterior ocelli vestigial.
Male usually ergatomorphic but winged in C. emeryi . In this form the antennae are 13-jointed but in ergatomorphic males they are 10- to 12-jointed; with long scape and more indistinct club. Petiole and postpetiole resembling the corresponding segments of the female, in the male of emeryi much as in the worker.
These minute ants are of Old World origin but several species have become widespread vagrants. Two of these occur in disturbed (mostly urban) habitats in California, where they nest in sidewalks and along roadways. Both are able to survive in sites invaded by the Argentine ant ( Linepithema humile ). The males of' Cardiocondyla occur in two forms: dispersing winged males and wingless, worker-like (ergatoid) males that mate in the nest.
Species identification: keys in Seifert (2003). Additional references: Anderson et al. (2003), Creighton and Snelling (1974), Cremer and Heinze (2003), Gulmahamad (1997), Heinze (1999), Heinze and Hölldobler (1993B), Heinze et al. (2004), Kugler (1984), MacKay (1995), Snelling (1974).
Cardiocondyla Emery, 1869: Ann. accad. Aspir. Nat. Napoli (2)2:20.
Type-species: Cardiocondula elegans Emery , 1869: Ann. Acad. Aspir. Nat. Napoli (2)2:21.
Distribution: Palaearctic, Ethiopian, Oriental, Australian, Polynesian, Nearctic & Neotropical regions.
Key to species
1- Propodeal spines very short and blunt (Fig.30); head, alitrunk, nodes and appendages reddish brown, gaster black ... C. nuda (Mayr)
- Propodeal spines long and acute (Fig.31); head, alitrunk, nodes and appendages yellow, gaster dark brown...... C. wroughtonii (Forel)
Taxonomy. The genus Cardiocondyla is assigned to the tribe Formicoxenini by Bolton (1994, 2003). 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.
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.
Vietnamese species. Five species have been recognized by us from Vietnam: kagutsuchi Terayama [= sp. eg- 3; = nuda (Mayr) in Eguchi et al., 2005] (Cuc Phuong, Tam Dao); minutior Forel [= sp. eg-2; = emery Forel in Eguchi et al., 2005] (Ba Vi, Cuc Phuong, Tam Dao); wroughtonii Forel [= sp. eg-1] (Tam Dao); sp. eg-4 (Tay Yen Tu); sp. eg-5 (Binh Chau-Phuoc Buu).
Bionomics. Cardiocondyla species inhabit open and man-made habitats such as around settlements and in gardens. Workers are frequently found on the ground surface.
