Ibotyporanga Mello-Leitão: tropical spiders in Brazilian semi-arid habitats (Araneae: Pholcidae)

Three new species of the previously monotypic ninetine genus Ibotyporanga Mello-Leitão, 1944 are described: I. emekori sp. n., I. diroa sp. n., and I. ramosae sp. n., all from the Brazilian state Bahia. All were collected in 'caatinga', a vegetation type that covers most of the area with semiarid climate in the northeastern region of Brazil. It is argued that two alternative explanations might account for the apparently almost universal restriction of ninetines to relatively inhospitable areas: they might be a relict group (possibly monophyletic), displaced from more favorable areas by more modern pholcids; or they might be a polyphyletic assemblage of lineages that independently evolved the ability to thrive in arid and semiarid areas by reducing their body size and appendage length to fit into spaces with tolerable microclimate. Preliminary cladistic analyses based on morphology alone have not been able to settle this question.