Original Research

Phylogenetic placement of the enigmatic Floodplain water snake, Lycodonomorphus obscuriventris FitzSimons, 1964

Chad Keates, Werner Conradie, Tatenda Dalu, Farai Dondofema, Eddie S. Riddell, Ryan J. Wasserman
Koedoe | Vol 64, No 1 | a1698 | DOI: https://doi.org/10.4102/koedoe.v64i1.1698 | © 2022 Chad Keates, Werner Conradie, Tatenda Dalu, Farai Dondofema, Eddie S. Riddell, Ryan J. Wasserman | This work is licensed under CC Attribution 4.0
Submitted: 07 October 2021 | Published: 28 June 2022

About the author(s)

Chad Keates, Department of Zoology and Entomology, Rhodes University, Makhanda, South Africa; and, South African Institute for Aquatic Biodiversity (SAIAB), Makhanda, South Africa
Werner Conradie, Port Elizabeth Museum, Humewood, South Africa; and, Department of Nature Conservation Management, Natural Resource Science and Management Cluster, Faculty of Science, Nelson Mandela University, George, South Africa
Tatenda Dalu, School of Biology and Environmental Sciences, University of Mpumalanga, Mbombela, South Africa
Farai Dondofema, Department of Ecology and Resource Management, University of Venda, Thohoyandou, South Africa
Eddie S. Riddell, Kruger National Park, South African National Parks, Skukuza, South Africa; and, Centre for Water Resources Research, University of KwaZulu-Natal, Pietermaritzburg, South Africa
Ryan J. Wasserman, Department of Zoology and Entomology, Rhodes University, Makhanda, South Africa; and, South African Institute for Aquatic Biodiversity (SAIAB), Makhanda, South Africa

Abstract

Lycodonomorphus is a genus of lamprophiid water snake endemic in Africa. Although widespread, abundant and presumably an important component of many aquatic and semi-aquatic food webs, these snakes are poorly understood taxonomically, particularly from a phylogenetic perspective. With only four of the nine species currently sequenced, this study attempts to improve our understanding of the evolutionary relationships within the genus through the phylogenetic placement of one of the most elusive species, Lycodonomorphus obscuriventris. Collected in the Ramsar declared Makuleke Wetlands in northern Kruger National Park (South Africa), the sample used in this study not only yielded the first DNA sequences for the taxon but also represented the most northerly South African record, bridging the gap between the southern and northern populations. The snake was sequenced for three partial mitochondrial genes (16S, Cyt-b, ND4) and one partial nuclear gene (c-mos) and phylogenetically placed, relative to the rest of the genus, using maximum likelihood (ML) and Bayesian inference (BI). Sequence divergences between sister taxa were also estimated using pairwise distance analysis. The concatenated phylogenetic reconstruction yielded similar topological structuring when compared to phylogenies from past articles, with both the ML and BI algorithms recovering strong support for L. obscuriventris as sister to a clade comprising of L. whytii + L. laevissimus + L. rufulus. The phylogenetic placement, albeit based on a single sample, challenges the original placement (morphological) of L. obscuriventris as sub-specific within L. whytii, suggesting that multiple species concepts should be considered when delineating species within this group.

Conservation implications: Prior to the discovery of the new record, the global distribution of L. obscuriventris was characterised by two disjunct populations. The new record bridges the distribution gap between these two populations, rendering the distribution continuous. This bodes well for the species as there is likely no barrier to gene flow, thereby buffering the species from localised threats given the more expansive distribution. Furthermore, given that the specimen was sampled from the Kruger National Park, the species is likely to be well-protected as much of its distribution within South Africa seems to fall within protected areas.


Keywords

Lamprophiidae; molecular systematics; water snake; range expansion; wetlands; African herpetology; Kruger National Park; Southern Africa

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