A revision of species included in the subgenus Laurentomantis (genus Mantidactylus) yielded new information about phylogeny, taxonomy, and biogeography of the endemic mantellid frog radiation in Madagascar. Four Laurentomantis species, distinguished by morphology and advertisement calls, are recognized: Mantidactylus (Laurentomantis) horridus (Northern and North-Western biogeographic regions), M. (L.) ventrimaculatus (South-East and East); M. (L.) malagasius (East); and the new species M. (L.) striatus (North-East). M. striatus and M. malagasius are probably sister species based on bioacoustic and morphological affinities. A tibial gland, so far unknown in anurans, is described in M. malagasius and M. horridus. A phylogenetic analysis of 54 mainly osteological and morphological characters in 33 endemic Malagasy anurans resulted in a position of Laurentomantis close to species of the subgenera Spinomantis and Gephyromantis (genus Mantidactylus), in accordance with its subgeneric status. However, also the well-established genus Mantella resulted to be nested within Mantidactylus, supporting the need of generic partitioning of the latter.