Phylogenetics of the freshwater crab (Potamonautes MacLeay, 1838) fauna from ‘sky islands’ in Mozambique with the description of a new species (Brachyura: Potamoidea: Potamonautidae)

Savel R Daniels,Vanessa Muianga,Julian Bayliss,Gabriela B Bittencourt-Silva

doi:10.5852/ejt.2020.716

Savel R Daniels, Vanessa Muianga + Show 2 more

Open Access

https://doi.org/10.5852/ejt.2020.716

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Abstract

Patterns and processes of cladogenesis among taxa living on the Mozambique ‘sky islands’ remain poorly studied. During the present study, we report on a new freshwater crab species from Mount Lico, an inselberg and ‘sky island’ in the Zambezia Province of Mozambique. Phylogenetic analyses using three mitochondrial DNA sequence loci (12S rRNA, 16S rRNA and COI) were used to determine the evolutionary placement of the freshwater crab specimens from Mount Lico. The freshwater crab specimens from Mount Lico were retrieved sister to Potamonautes choloensis. The new species, Potamonautes licoensis sp. nov., is described and compared with other southern African freshwater crab species. Divergence time estimations for the Mozambican freshwater crab species suggest a Miocene / Plio–Pleistocene diversification. Some endemic ‘sky island’ species form an early branching and are sister to other predominantly East African species, while other ‘sky island’ species are more recently derived and nested within a predominantly southern African clade. The present study presents the description of the fourth endemic freshwater crab species from Mozambique and suggests that the species diversity in the country is likely highly underrepresented, reiterating the call for renewed systematic surveys. An argument for the conservation of these mountainous ‘sky islands’ is presented.

Highlights

The East African Afrotemperate biodiversity hotspot, one of eight on the continent, extends from the Eritrean highlands along the East African coast including Djibouti, Ethiopia, Kenya, Rwanda, Burundi, Uganda, the eastern Democratic Republic of the Congo, Tanzania and Zimbabwe, and terminates in Mozambique (Mittermeier et al 2004)
Clade 1 (1.00 posterior probabilities (pP) / 98%) contained five east African freshwater crab species, all occurring in Mozambique; the endemic P. namuliensis, sister to P. obsesus A
Our results clearly demonstrate the presence of a new freshwater crab species from Mount Lico, from the Zambezia Province in Mozambique

Summary

Introduction

The East African Afrotemperate biodiversity hotspot, one of eight on the continent, extends from the Eritrean highlands along the East African coast including Djibouti, Ethiopia, Kenya, Rwanda, Burundi, Uganda, the eastern Democratic Republic of the Congo, Tanzania and Zimbabwe, and terminates in Mozambique (Mittermeier et al 2004). The region contains three ancient blocks of mountain massif, the Eastern Arc Mountains and Southern Rift, the Albertine Rift and the Ethiopian Highlands, while the volcanic highlands of Kenya and Tanzania are of more recent, early Miocene origin (Davidson & Rex 1980; Sepulchre et al 2006). Speciation in the southern mountains of the East African hotspot is poorly studied in comparison to that in the central and northern regions (Assefa et al 2007; Demos et al 2014). Phylogenetic studies have been conducted on several vertebrate groups (Taylor et al 2012; Branch et al 2014; Conradie et al 2018), but the invertebrate fauna of the ‘sky islands’ has to date received limited alpha taxonomic attention and evolutionary relationships remain poorly understood

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