ADETOMYRMA, AN ENIGMATIC NEW ANT GENUS FROM MADAGASCAR (HYMENOPTERA, FORMICIDAE), AND ITS IMPLICATIONS FOR ANT PHYLOGENY

Adetomyrma venatrix, representing a new genus and species of ant, is d escribed from a single collection of twenty-one workers from Zombitse Forest, in western Madagascar. Remarkable features of its morphology i nclude: (i) absence of a petiole in dorsal view (abdominal tergum 3 la cking a dorsally differentiated pretergite), (ii) gaster large and exp anded posteriorly, all terga and sterna unfused and without constricti ons, (iii) absence of eyes, and (iv) presence of a very large sting (l arger, in relation to body size, than that of any other known ant). Ad etomyrma does not possess any of the derived features heretofore said to characterize the existing ant subfamilies. Morphological evidence s uggests, however, that it is cladistically a member of the ponerine tr ibe Amblyoponini despite the absence of apomorphic abdominal character s (tergostemal fusion of abdominal segments 3 and 4) seen in all other Ponerinae and in the more inclusive 'poneroid group' of subfamilies. Whether A detomyrma shows primitive absence of such characters or seco ndary reversal to an unfused state has important implications for the higher phylogeny of the ants. There is insufficient evidence to choose decisively between these two alternatives, but in either case the mon ophyly of the ant subfamily Ponerinae becomes doubtful.