The Linnean shortfall in action: amphibian surveys reveal undocumented species in the Nguru Mountains, Tanzania

The Nguru Mountains in the central Eastern Arc Mountains (EAM) consist of three main protected areas (Mkingu, Kanga and Magotwe), which form an important hotspot for endemic species of vertebrates and plants in Tanzania. However, the herpetofauna of the Nguru are relatively poorly understood, and rapid deforestation highlights the urgent need for comprehensive biodiversity studies. Using standardized survey methods, we conducted amphibian surveys in Nguru Mountains between May 2022 and November 2024, and together with literature and databases search, we provide an annotated amphibian checklist. Using molecular barcoding, we identify 42 lineages of amphibians in the Nguru Mountains, 15 of which are candidates for species new to science. Twenty-eight lineages are endemic to the Eastern Arc Mountains of Tanzania, eight of them being restricted to Nguru. Treating these new records as species would rank the Nguru Mountains third out of the 12 Eastern Arc Mountain blocks for the number of endemic amphibians, after Udzungwa and Uluguru. However, the identified lineages await formal description, and the partial sampling and taxonomic issues detected here, are common to all Eastern Arc Mountains. This study therefore highlights the reality of the Linnean shortfall even in recognized biodiversity hotspots, and how taxonomic work is required to remedy this. The impact of deforestation on Nguru amphibians is yet to be quantified, however this study helps to form a baseline for future studies.