Fig 1.
The study area showing the Operational Geographic Units (OGUs).
The Maputaland-Pondoland-Albany (MPA) biodiversity hotspot is demarcated by the dashed line and the OGUs considered here as MPA units are indicated in dark grey, while the greater MPA region of vertebrate endemism [24] is in light grey. The OGUs are labelled as: ACB–Albany coastal belt, AWB–Amatola-Winterberg, CBV–central Bushveld, CFR–Cape Floristic Region except Knysna transition zone, DBP–Drakensberg plateau, DEE–Drakensberg-Eastern Cape escarpment, DKE–Drakensberg-KwaZulu-Natal escarpment, HUK–Highveld-upper Karoo, INH–Inhambane, KBV–Kalahari-Bushveld, KNY–Knysna transition zone (shared between the Cape Floristic Region and the greater MPA region), KUK–Kalahari-upper Karoo, LKR–lower Karoo, MLV–Mozambique lowveld, NBV–northern Bushveld, NCB–Natal coastal belt, NDH–northern dry Highveld, NGO–Ngoye, NMD–Natal Midlands, NME–northern Mpumalanga escarpment, NMH–northern mesic Highveld, NMO–northern mopane, NMP–northern Maputaland, NMV–northern Middleveld, NNT–northern Natal, PND–Pondoland, SDH–southern dry Highveld, SKR–Succulent Karoo, SME–southern Mpumalanga escarpment, SMH–southern mesic Highveld, SMO–southern mopane, SMP–southern Maputaland, SMV–southern Middleveld, SNB–Sneeuberg, SPB–Soutpansberg, STR–southern Transkei coastal belt, TMD–Transkei Midlands, UKR–upper Karoo, WLB–Wolkberg, WTB–Waterberg. See text for further details. The MPA hotspot boundary is reprinted from Hoffman et al. [26] (public domain).
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.
Fig 3.
Land snail species richness, endemism and percentage endemicity within the MPA hotspot, MPA-Knysna province and the greater MPA region of land snail endemism.
Table 1.
Proposed regionalisation hierarchy for land snail zoogeography in south-eastern Africa (SEA).
Table 2.
Land snail species selected for the study (n = 73; representing 12 genera and three families) and their endemism within the Maputaland-Pondoland-Albany (MPA) biodiversity hotspot, the MPA-Knysna province, the greater MPA region of land snail endemism, and the south-eastern Africa (SEA) dominion.
Fig 4.
Centres of endemism (COEs) and centres of narrow endemism (CONEs) for land snails of south-eastern Africa derived from the phenetic cluster dendrogram (Fig 2A).
Centres are shaded on a grey scale based on number of endemics, given below for each in brackets (darker shades denote high endemism). See Table 3 for lists of endemic species. (a) COEs: A–Sky islands (4), B–Extended Maputaland (4), C–Natal (6), D—Extended Pondoland (7), and E—Albany-Knysna (7). (b) CONEs: a—Soutpansberg (2), b—Wolkberg (2), c—Northern Middleveld (2), d—Natal coastal belt-Ngoye (3), e—Natal Midlands, and f—Knysna (3). The whole (blue) line indicates the Maputaland-Pondoland-Albany (MPA) hotspot boundary while the dashed (black) line delimits the greater MPA region of land snail endemism. COEs and CONEs are spatially compared with (c) South African biomes and (d) the protected area network of South Africa (SA); protected areas in Lesotho (L), Swaziland (S) and Mozambique (M) are not included. The MPA hotspot boundary, biomes and protected areas of SA are reprinted from Hoffman et al. [26], Open Knowledge Foundation [67] and the Department of Environmental Affairs, Forestry and Fisheries [68] (public domain), respectively.
Table 3.
Range-restricted species endemic to centres of endemism (COEs), centres of narrow endemism (CONEs) and areas of endemism (AOEs) within the south-eastern Africa dominion (see Fig 4), also showing their nested hierarchy, verification as and areas of endemism (AOEs) and corresponding biotic elements (see text for details).
Fig 5.
Delineation of areas of endemism (AOEs) for land snails in south-eastern Africa based on the strict consensus tree of parsimony analysis of endemicity (PAE).
Four of the five clades in the area cladogram harbour more than two sympatric endemic species, and hence identified as AOEs, together with two OGUs each with two narrow endemics with congruent ranges. All six AOEs are shaded in the map on a grey scale according to the number of endemic species, given below for each in brackets (darker shades denotes high endemism; see Table 3 for lists of endemic species): A—Soutpansberg (2), B—Wolkberg (2), C—Extended Maputaland (4), D—Natal (6), E—Extended Pondoland (7), and F—Albany-Knysna. The MPA hotspot boundary is reprinted from Hoffman et al. [26] (public domain).
Fig 6.
Biotic elements of land snails in south-eastern Africa.
(a) First two dimensions of the nonmetric multidimensional scaling of the distribution ranges of land snails of south-eastern Africa based on their incidence in pre-defined operational geographic units (Fig 1). Biotic elements found by PRABCLUS are denoted by 1‒9; N = noise component. (b) Distribution maps of the nine biotic elements of the land snail fauna of south-eastern Africa. Four different shadings from light to dark indicate the areas where >30%, >45%, >60% and >100% of the species of each element are present. The MPA hotspot boundary is reprinted from Hoffman et al. [26] (public domain).
Fig 7.
Spatial patterns of land snail fauna in south-eastern Africa (SEA).
Species richness for the whole study area and all spatial measures on endemism for the SEA dominion (see Fig 2). (a) species richness, (b) SEA dominion endemism, (c) narrow endemism, (d) weighted endemism and (e) corrected weighted endemism. See text for details on above calculations. The whole (blue) line indicates the Maputaland-Pondoland-Albany (MPA) hotspot boundary while the dashed (black) line delimits the Greater MPA region of land snail endemism. The MPA hotspot boundary is reprinted from Hoffman et al. [26] (public domain).
Table 4.
Comparison of centres and areas of land snail endemism in south-eastern Africa (SEA), defined in the present study through UPGMA clustering, PAE and BEA with similar areas defined for Sciobius weevils of south-eastern Africa using various methods employed in previous studies.