Land snail biogeography and endemism in south-eastern Africa: Implications for the Maputaland-Pondoland-Albany biodiversity hotspot

corrected WE [56]). Values obtained for all measures were normalized to stand between 0 and 1. Each of the above parameters were mapped using ArcMap10.1 [66] with a graduated grey scale for a maximum of five classes determined by natural breaks calculated using Jenk’s opti- misation, so that the patterns inherent in the data are best revealed. Results Biogeography of land snails in south-eastern Africa The first ever numerical regionalisation for land snails in south-eastern Africa is presented in Fig 2 and Table 1. An initial division of the UPGMA dendrogram (Fig 2A) separates a very Fig 2. Proposed zoogeographical regionalisation for land snails of south-eastern Africa. (a) Dendrogram of hierarchical relationships between operational geographic units (OGUs), based on UPGMA clustering with Jaccard’s coefficient of similarity. The hierarchy of zoogeographical entities were established using phenon lines of increasing similarity: Do = dominion; Sd = subdominions; Pr = provinces; Sp = subprovinces and Ds = districts. Centres of endemism (dark grey) and centres of narrow endemism (light grey) are also recognized from the same dendrogram, and mapped in Fig 4. Three letter codes for OGU names follow Fig 1. (b) The proposed hierarchical zoogeographical regionalisation of the South- Eastern Africa (SEA) dominion (thick dark red boundary; Lowveld and Cape dominions respectively in north-east and south-west are also indicated). The coloured phenon lines in panel (a) defines subdominions, provinces, subprovinces and districts of the SEA dominion, listed in

Table 1, with respective codes for provinces (A-C), subprovinces (A1, A2, etc.). Entities labelled on the map are subprovinces (Sp) and districts (Ds); S = South, N = North and KZN = KwaZulu-Natal. (c) Malacofaunal provinces within the two subdominions of SEA dominion (separated by thick purple boundary): MPA-Highveld subdominion with three provinces—MPA-Knysna province (light green), Highveld province (pale orange) and Bushveld province (olive green); and southern escarpment subdominion with no subordinate provinces (pale maroon). OGUs shown here in white (and marked with × on the dendrogram) do not form geographically contiguous clusters, and were hence dissolved into the geographically nearest and ecologically closest biogeographical entity (see discussion for more details). MPA hotspot boundary is reprinted from Hoffman et al. [26] (public domain) in blue to show its recovery as a valid zoogeographical entity (MPA-Knysna province), despite an extension towards Knysna in south-west. https://doi.org/10.1371/journal.pone.0248040.g002 PLOS ONE Land snail endemism in the Maputaland-Pondoland-Albany biodiversity hotspot PLOS ONE | https://doi.org/10.1371/journal.pone.0248040 March 4, 2021 7 / 26