Abstract—Males ofIdea tambusisiana, previously unstudied, lack the only known unequivocal synapomorphy associating the constituent members ofIdea. Further cladistic analyses were performed on an expanded data matrix containing two characters alternatively coded in binary and multistate form. Two topologies were obtained of which one, in whichI. tambusisianaremains internal to the genus, is accepted following consideration of information content and assessment of the supporting character states. A character analysis is also performed in which the problem of ambiguous charater state assignments to the internal nodes of the cladogram is examined. Biogeographic implications of the results are discussed with respect to areas of endemism in southeast Asia, the origin of Sulawesi (Celebes), and vicariance/dispersal models intended to explain the distribution ofIdeaspecies in relation to the Makassar Strai