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Cardiocondyla kagutsuchi is a small (~2 mm) dark brown to black species with short antennal scapes, propodeal spines reduced to small angles and without erect hairs on its mesosoma. It is difficult to distinguish from its other introduced congeners, and nearly impossible to distinguish from its presumed sister species, C. mauritanica. The species is presumably native to Asia, and has spread across the Pacific where it has commonly been misidentified as C. nuda (Seifert, 2003). The species is generally considered inconspicuous, and it is not considered a pest anywhere in its range.
A tramp across Asia and the Pacific.
Native range. Tropical Asia.
Current range includes. Sri Lanka, E India, Nepal, Bhutan, S China, Korea, S Japan, Philippines, Malaysia, Indonesia, Papua New Guinea, Guam, Hawaii, Fiji.
In Fiji: Viti Levu: Lautoka Port 5 b.
In Hawaii: Hawaii, Maui, Oahu and Kauai
Seifert (2003)attributed the unusual success of Cardiocondyla species (including C. kagutsuchi) establishing outside their native range by the very small space needed for nest construction, the expressed polygyny in several species, a sufficient survival rate after shortage of water, and in particular the fact that, in some species, a dozen of detached workers with brood can establish a fully reproductive new colony containing all castes.
Seifert (2003)also relays a communication from K. Yamauchi who reported for all six of his study sites on Okinawa, in Malaysia, and in Indonesia that C. kagutsuchi nested in shallow soil in open, disturbed areas with bare or weakly herbaceous ground. Like other Cardiocondyla, it is omnivorous. What little else is known about the biology of C. kagutsuchi comes from studies investigating sex ratio and caste determination (Frohschammer & Heinze, 2009a; Narita et al., 2010; Schwander et al., 2010; Yoshizawa et al., 2009). Cardiocondyla kagutsuchi has sex mosaics of queens (gynandromorphs; mosaic of queens and winged male) and workers (ergatandromorphs; mosaic of worker and wingless ergatoid male). The species has unusually long-lived, heavily armed ergatoid males performing a constant spermiogenesis throughout their whole imaginal life (Heinze et al., 1993). These males usually stay within the mother nest, mate intranidally, and try to monopolize all matings by killing other ergatoid males, preferentially when these still are in the pupal stage.
Cardiocondyla kagutsuchi is believed to be sister species to C. mauritanica which it replaces across its range, and it is possible that the former may actually be a distinct population of the latter rather than a genetically isolated species (Seifert, 2003).
Among introduced Cardiocondyla species, C. kagutsuchi (together with C. mauritanica, C. minutior, and C. venustula) is differentiated from C. emeryi, C. obscurior and C. wroughtonii by (1) its weakly impressed to absent metanotal groove; (2) short propodeal spines that are reduced to right angles (those of C. minutior are of moderate length); and (3) a postpetiole that is lower than the petiole and lacking a distinct ventral bulge. Cardiocondyla kagutsuchi and C. mauritanica are separated from C. venustula by the more angulate postpetiolar sides, which in dorsal view give the postpetiolar disc a hexagonal appearance. Separating the former two species is difficult, and the reader is referred to Seifert (2003), who writes that C. kagutsuchi can be separated from C. mauritanica by it longer spines, higher petiole, broader postpetiole, shorter scape and shorter gaster pubescence.
Diagnosis among workers of introduced and commonly intercepted ants in the United States. Worker caste monomorphic. Head shape subrectangular. Antenna 12-segmented. Antennal club 3-segmented. Antennal scapes easily extended beyond eye level but scapes do not extend beyond posterior margin of head. Antennal scrobe lacking. Antennal insertion not surrounded by a raised sharp-edged ridge. Eyes greater than 5 facets; not unusually large (distinctly less than half head length). Posterolateral corners of head unarmed, without spines. Mandibles triangular. Mesosoma lacking erect hairs. Metanotal groove absent to shallow; not distinctly impressed. Pronotal spines absent. Propodeal spines short. Slope of mesosoma gradual. Waist 2-segmented. Petiole with a distinct and upright node; lacking large subpetiolar process. Petiolar peduncle long (length distinctly twice or more than height); does not taper gradually into node. Postpetiole appearing swollen. In dorsal view postpetiole wider than long and much broader than petiole; with gently rounded anterolateral corners; sides angulate giving the postpetiolar disc a hexagonal appearance. Postpetiole lower than petiole and lacking a distinct ventral bulge. Upper surface of gaster attached to postpetiole. Color polymorphism: most frequent light morphs with a yellowish to medium brown mesosoma and waist, head a little darker, gaster blackish brown, and antennal club dark brown; rarer dark morphs (Philippines) with blackish brown head and gaster and dark brown mesosoma and waist.
Frohschammer, S. & Heinze, J. (2009) A heritable component in sex ratio and caste determination in a Cardiocondyla ant. Front. Zool., 6: 27, 6 p.
Heinze, J., Cremer, S., Eckl, N. & Schrempf, A. (2006) Stealthy invaders: the biology of Cardiocondyla tramp ants. Insect. Soc., 53, 1-7.
Heinze, J., Kühnholz, S., Schilder, K. & Hölldobler, B. (1993) Behavior of ergatoid males in the ant, Cardiocondyla nuda. Insect. Soc., 40, 273-282.
Narita, S., Pereira, R.A.S., Kjellberg, F. & Kageyama, D. (2010) Gynandromorphs and intersexes: potential to understand the mechanism of sex determination in arthropods. Terrest. Arthropod Rev., 3, 63-96.
Reimer, N.J. (1994) Distribution and impact of alien ants in vulnerable Hawaiian ecosystems. In: Williams, D.F. (Ed.) Exotic ants. Biology, impact, and control of introduced species. Westview Press, Boulder. xvii + 332 p., pp. 11-22.
Schwander, T., Lo, N., Beekman, M., Oldroyd, B.P. & Keller, L. (2010) Nature versus nurture in social insect caste differentiation. Trends Ecol. Evol., 25(5), 275-282.
Seifert, B. (2003) The ant genus Cardiocondyla (Insecta: Hymenoptera: Formicidae) - A taxonomic revision of the C. elegans, C. bulgarica, C. batessi, C. nuda, C. shuckardi, C. stambuloffi, C. wroughtoni, C. emeryi, and C. minutior species groups. Ann. Naturhist. Mus. Wien Ser. B. Bot. Zool., 104, 203-338.
Terayama, M. (1999) Taxonomic studies of the Japanese Formicidae, Part 6. Genus Cardiocondyla Emery. Mem. Myrmecol. Soc. Jpn., 1, 99-107.
Yoshizawa, J., Mimori, K., Yamauchi, K. & Tsuchida, K. (2009) Sex mosaics in a male dimorphic ant Cardiocondyla kagutsuchi. Naturwissenschaften, 96, 49-55.
Found most commonly in these habitats: 1 times found in central crater, 2 times found in port of entry/city, 1 times found in urban garden, 1 times found in dist. habitat, 1 times found in lava flow.
Found most commonly in these microhabitats: 1 times nest under ground, 1 times ground forager(s), 1 times foraging on ground, 1 times ground foragers.
Collected most commonly using these methods: 1 times aspirating, 2 times hand collection, bait, recruiting to, 2 times hand collection, 1 times Pitfall.
Elevations: collected from 1 - 2134 meters, 857 meters average