Werner Conradie, Gabriela B. Bittencourt-Silva, Harith M. Farooq, Simon P. Loader, Michele Menegon and Krystal A. Tolley..

ABSTRACT

Nothophryne Poynton, 1963 is a monotypic genus of frog, with the nominal species N. broadleyi found only on Mount Mulanje, in southern Malawi. Recent surveys in northern Mozambique, however, have uncovered at least four new species associated with four inselbergs (Mount Inago, Mount Namuli, Mount Ribáuè and Taratibu Hills). Previous phylogenetic analyses using mitochondrial genes suggest that each mountain isolate has an endemic species of Nothophryne. Herein we provide a rediagnosis of the genus and comparative diagnoses of four new species based on new material.

Introduction:

Northern Mozambique is regarded as one of the most poorly studied areas in southern Africa particularly in terms of herpetofauna (Poynton & Broadley 1985; Tolley et al. 2016). In recent years, biological surveys of some of the many inselbergs have been conducted (e.g. Branch et al. 2005; Timberlake et al. 2007, 2009, 2012; Portik et al. 2013a; Bayliss et al. 2014; Farooq & Conradie 2015; Farooq et al. 2015; Conradie et al. 2016). These field studies have produced new records of range-restricted reptiles and amphibians and the discovery of new species (Branch & Bayliss 2009; Branch & Tolley 2010; Portik et al. 2013b; Branch et al. 2014). Given that species level phylogenies often reveal additional lineages, it has become clear that many taxonomic groups associated with these sky islands likely contain cryptic taxa (e.g. Branch & Tolley 2010; Branch et al. 2014).

The mongrel frog Nothophryne broadleyi Poynton (1963) was described from Mount Mulanje in southern Malawi as a monotypic genus. The species is named after the late Zimbabwean herpetologist Don Broadley who was the first to collect this frog. Later, during an expedition to northern Mozambique lead by Don Broadley, two individuals of Nothophryne were collected from Mount Ribáuè (Blake 1965). Poynton (1966) assigned this material to the nominal species, N. broadleyi, although he noted a slight difference in hindlimb length and the presence of slightly expanded fingertips. He regarded these differences to be to minor and therefore not supporting its distinctiveness as a new species.

Nothophryne are relatively small frogs from the family Pyxicephalidae that are found on rocky outcrops associated with mossy patches and water rivulets from seepages. Their fingertips are swollen, which facilitate adherence on slippery rock surfaces (Poynton 1963, 1966). Eggs are laid on wet moss and the semi-terrestrial larvae are found in the thin water film over the rock surface. The landscape in northern Mozambique consists of numerous smaller granite inselbergs, as well as other larger mountains (e.g. Mount Namuli, Mount Inago and Mount Ribáuè), which was believed to be excellent habitat for Nothophryne.

In 2014 and 2017 we had the opportunity to visit Mount Ribáuè in the footsteps of Don Broadley, where we collected a series of Nothophryne specimens. We also collected additional material from other localities (Mount Namuli and Mount Inago, and Taratibu Hills) in northern Mozambique. Bittencourt-Silva et al. (2016) identified at least four cryptic lineages of Nothophryne from the above-mentioned mountains using the Bayesian mixed Yule-Coalescent model (bGMYC) for species delimitation and uncorrected pairwise distances between 16S ribosomal DNA sequences. Given those results, we use morphological and acoustic data to revisit the taxonomic status of the Mount Ribáuè population, as well as the additional populations on Mount Inago, Mount Namuli, and Taratibu Hills in northern Mozambique. Furthermore, we provide uncorrected pairwise distances (p-distances) between sequences of one nuclear and one mitochondrial genes of Nothophryne.

Key words: Africa; amphibian; inselbergs; Pyxicephalidae; species; taxonomy.
 

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