Cardiocondyla minutior Forel 1899
Synonyms (Seifert 2003 )
Cardiocondyla nuda var . minutior Forel , Cardiocondyla sukuyomi Terayama
There are over 40 known species of Cardiocondyla , the majority of which are to be found in warmer parts of the Old World. Australia possesses only four species. C. minutior is a tramp species, apparently absent in Australia, which has only recently arrived here, probably through the port of Tauranga from the Pacific region to the north.
Distribution (see map)
First recorded in Mt Maunganui, Tauranga, on 19 March 2000; further specimens were collected there the following year (Harris & Berry 2001). Establishment in Tauranga at least seems assured. Specimens were collected at the Port of Napier in 2002, but whether establishment has taken place there remains to be ascertained. Also in doubt is whether this species is capable of successful long-term establishment, given its clear preference for warmer climates.
In the genus Cardiocondyla , in side view the pronotum, mesonotum and propodeum form a continuous flat or weakly arched surface interrupted only by the shallow metanotal groove. The postpetiole is swollen, wider than long, and much broader than the petiole when viewed from above.
Diagnostic features of the worker
Length 2.4 mm; antennae 12-segmented, with a distinct 3-segmented club; propodeum strongly armed with two blunt teeth; colour brown, with head and gaster darker than the mesosoma and petiole. Seifert (2003) provides a key to all Holarctic species groups.
Shattuck (1999) writes that " Cardiocondyla species are ground nesting and most workers also forage on the ground surface. They are only occasionally found foraging arboreally." Workers carry out a primitive form of recruitment communication called tandem running in which only a single worker is recruited at a time and the follower has to stay in direct antennal contact with the leader. The pair then proceed to the target site (Hōlldobler & Wilson 1990). Their small size and slow movement mean workers are often overlooked by the casual observer.
An unusual feature of colony structure is the striking male dimorphism. In small colonies there are both normal winged males and wingless (ergatoid) males. The latter are highly aggressive, attacking and killing ergatoid rivals, especially young ones, whereas the former are non-aggressive. Only the ergatoid morph is produced in those species that have large colonies. Both morphs are capable of inseminating nestmate queens.
Impacts not known, but considered unlikely to be a pest.
Compiled by Warwick Don & Richard Harris