Spiders collected as part of a rapid biodiversity survey in an isolated forest patch in the northern part of Madagascar contained a new species of Katableps. The male of Katableps lilyarisoni n. sp. is characterized by the pale fusiform metatarsus and tarsus of the first leg pair and details of the palp, the female by the widely separated spermathecae and broad copulatory ducts. It is most likely that other forest patches may contain more species of this remarkable taxon of forest-dwelling lycosids.