Kimboza, a small lowland forest with an outstanding herpetofauna diversity in East Africa

The Eastern Arc Mountains (EAM) and Coastal forests of Tanzania are renowned for harboring large numbers of threatened and endemic vertebrate species, yet most of these areas have been partially studied. The Kimboza Nature Forest Reserve (KNFR) is a small forest which is in transition between the EAM and Coastal forests, and among the poorly surveyed areas for amphibians and reptiles. We conducted systematic surveys across the KNFR in 2012 and between 2020 and 2023 using a range of approaches with the aim of establishing a comprehensive and updated list of reptile and amphibian species and assessing the contribution of EAM and Coastal forests to the KNFR's herpetofauna. We identified 77 species, 29 amphibians and 48 reptiles, substantially updating previous species lists. Three of these species (Kinyongia magomberae, Trachylepis boulengeri, and Philothamnus macrops) represent range extensions from previously known ranges. Fourteen species are endemic to East Africa, 11 of them being restricted to Tanzania. These results make the KNFR the richest forest reserve for herpetofauna per square km in Tanzania, and most similar in its composition to the Coastal, rather than Eastern Arc forests. With the caveats concerning taxonomic uncertainties and the inequalities of sampling intensity across the region, this study shows that the KNFR is an important area that deserves conservation attention. The KNFR, like other Coastal forests, is under significant pressure from anthropogenic activities which call for urgent action to protect this small but rich forest.

Methods
This study combines two short herpetofauna surveys (two nights, December 2012 and three nights, January 2023) with an intensive fieldwork of 11 months (December 2020 to June 2022). The 2012 and 2023 surveys used time constrained searching only, and the 2020–2022 involved time constrained searching in all months, and two lines of bucket pitfall trapping with a drift fence in May 2021. We also compiled information on other surveys conducted in the KNFR from the literature and biodiversity databases. We queried biodiversity databases (GBIF; www.gbif.org (https://doi.org/10.15468/dl.t26vw9, and https://doi.org/10.15468/dl.kth9yd), VertNet; www.vertnet.org, iNaturalist; www.inaturalist.org) and Google Scholar between March 10 and May 18 2024 using a combination of “Amphibia/Reptilia/Herpetofauna” and the reserve's boundary to find any record of these taxa from the forest reserve. We also queried the biodiversity database of the University of Dar es Salaam, and museum records of the Natural History Museum in London to access records of specimens deposited by previous researchers. All resulting species lists were curated to use the current nomenclature (Amphibians species of the world, Frost 2024 for amphibians and The reptile database, Uetz et al. 2023 for reptiles) and resolve species with uncertain identities, e.g., those which were not identified to species level, undergone taxonomic revisions or represent mis-identifications. To understand the position of the KNFR in terms of herpetofauna species when compared to other Coastal and Eastern Arc forests, we compare its species richness to records of amphibians and reptiles from Coastal forests of Tanzania and Eastern Arc Mountain blocks from Burgess and Clarke (2000) and Rovero et al. (2014). We supplemented these two sources by searching for other published and unpublished reports in Google scholar, and occurrence data from VertNet and GBIF between 10 March to 18 May 2024 using the name of each forest (see Burgess and Clarke (2000) and Rovero et al. (2014) for the list of forests used) together with the word amphibia/reptilia. The resulting species lists are listed in Excell with all the associated information.