Madabolus, gen. nov. is described to accommodate M. maximus, sp. nov. (type species) from several localities in western Madagascar. A phylogenetic analysis of 26 spirobolidan taxa, based on morphological characters, places Madabolus, gen. nov. with the Afrotropical genera Pelmatojulus de Saussure, 1860; Pachybolus Cook, 1897; Hadrobolus Cook, 1897 and Epibolus Cook, 1897. The tribe Pachybolini is proposed to include Madabolus, gen. nov. and the four abovementioned genera. Putative autapomorphies of Pachybolini are: a closed incisura lateralis; setae of gnathochilarial lamella lingualis apical; vulva kidney- or crescent-shaped, with valves meeting in a sinuous fissure and crest protruding. Within Pachybolini, Pelmatojulus (West Africa) stands out by virtue of an increased number of apical antennal sensory cones, with great probability an apomorphy. Madabolus, gen. nov. and east African genera of the tribe share another potential synapomorphy, namely, an increased number of setae on the gnathochilarial lamellae linguales. Other Malagasy genera of Pachybolidae do not seem to be related to Afrotropical genera.