Contributions to Zoology, 70 (4) (2002)Miguel Vences; Frank Glaw; Franco Andreone; Riccardo Jesu; Giovanni Schimmenti: Systematic revision of the enigmatic Malagasy broad-headed frogs (Laurentomantis Dubois, 1980), and their phylogenetic position within the endemic mantellid radiation of Madagascar

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Introduction

Recent phylogenetic studies based on mitochondrial DNA sequences suggested that the endemic Malagasy frogs of the genera Aglyptodactylus, Boophis, Laliostoma (previously Tomopterna), Mantidactylus and Mantella form a monophyletic lineage (Richards and Moore, 1998; Bossuyt and Milinkovitch, 2000; Richards et al., 2000; Vences et al., 2000), although they had been previously assigned to three different subfamilies in the family Ranidae (Blommers-Schlösser, 1993). Based on the genetic evidence, Vences and Glaw (2001) proposed including representatives of the five genera in a separate family Mantellidae, with three subfamilies (Mantellinae, Boophinae, Laliostominae).

Molecular studies on Mantidactylus included single representatives of eight subgenera (Richards et al. 2000), but morphological phylogenies of this genus based on an adequate number of characters and terminal taxa have so far not been published (see Glaw et al., 1998). While Mantella, Aglyptodactylus and Laliostoma are well defined lineages with a limited number of species, Boophis and Mantidactylus are speciose, with about 40 and 75 nominal species, respectively. Especially Mantidactylus, currently partitioned into 12 subgenera (Glaw and Vences, 1994), contains very diverse frogs both in size and morphology as well as in habits and reproductive modes. Basic data on ecology and reproductive biology are incomplete or totally lacking for many species of Mantidactylus and Boophis. To understand how the mantellid radiation could give rise to its present extraordinary diversity in Madagascar, it is crucial to gatherinformation on its less known lineages.

Despite of the important recent progress in knowledge on the batrachofauna of Madagascar (Glaw and Vences, 2000), a number of groups remain largely unknown. Such is the case for the frog species classified in Laurentomantis, which at present (Glaw and Vences, 1994) is considered as subgenus of Mantidactylus: Mantidactylus (Laurentomantis) horridus (Boettger, 1880), M.(L.) malagasius (Methuen and Hewitt, 1913) and M.(L.) ventrimaculatus (Angel, 1935). The monograph of Blommers-Schlösser and Blanc (1991) contained no information on habitat, biology or life coloration of any Laurentomantis species. Blommers-Schlösser and Blanc (1993) showed, for the first time, a photograph of a living M. malagasius. Glaw and Vences (1994) provided photographs, call descriptions and natural history notes for two different morphs referred to this species from the Central East and Marojejy in the North-East, and reported the discovery of an adult M. horridus at Montagne d’Ambre in northern Madagascar.

The nomenclatural and taxonomic history of Laurentomantis is extensive and still confusing. While Boettger (1880) described the taxon horridus as Hemimantis horrida, Boulenger (1882) treated this species as Arthroleptis horridus. Methuen and Hewitt (1913) erected the genus Microphryne to accomodate their taxon malagasius (as M. malagasia), and assumed that horrida belonged to this genus as well. As the name Microphryne was preoccupied, Methuen (1920) created the replacement name Trachymantis. However, as demonstrated by Dubois (1980), Trachymantis was also preoccupied (by Trachymantis Giglio-Tos, 1917). Dubois (1980) thus created the replacement name Laurentomantis, which was considered to merit genus rank by Blommers-Schlösser and Blanc (1991) and Dubois (1992). Glaw and Vences (1994), however, concluded that no phylogenetic data exist to consider Laurentomantis as a separate genus in addition to the speciose Mantidactylus, and consequently considered Laurentomantis as a subgenus of Mantidactylus.

During the last years, numerous additional specimens of Laurentomantis were collected during surveys in several regions of Madagascar. In the present paper we review the Laurentomantis material available to us (more than 45 specimens), provide detailed morphological and bioacoustic data, and describe one new species. We furthermore undertake a phylogenetic analysis of 33 species, representing all mantellid genera, to assess the position of Laurentomantis relative to them, and to draw hypotheses on the origin and evolution of this radiation.