Arisaema madhuanum, a new species of Araceae from the southern Western Ghats, is described and illustrated. The new species is morphologically allied to Arisaema attenuatum, from which it differs in having subulate neuters on the male spadix, a wide-mouthed spathe tube with the margins dilated into broad auricular extensions, and an erect to arching, oblong-lanceolate spathe limb with a narrow constricted basal region. The new taxon belongs to Arisaema sect. Sinarisaema Nakai.