Abstract:
Invertebrate diversity is often neglected in conservation planning initiatives. There are also very
few large-scale diversity studies in Africa, with most studies being restricted to single properties
and spatial extents that are on average not much larger than 30 km2. Here, we provide a
comparative regional assessment, two orders of magnitude larger than usual (30 000 km2), of
epigeal spider, beetle and millipede diversity in the Vhembe Biosphere Reserve – the largest
biosphere reserve in South Africa, and one of the largest in Africa. Firstly we aim to provide an
evaluation of the ability of a range of broad and fine scale predictors to explain the variation in the
diversity of these taxa. Secondly, we measured cross-taxon congruence between our selected
invertebrate taxa and woody vegetation, and within-taxon surrogate efficiency. Thirdly we
evaluated performance of existing and proposed zonations in representing regional invertebrate
species diversity. Finally, to aid in the development of species conservation profiles for lesser
known taxa, annotated check lists are provided for two neglected but dominant epigeal beetle
families, Tenebrionidae and Carabidae. Vegetation units explained the largest and most significant
component of beetle and spider diversity (richness and complementarity of alpha and beta
diversity). Elevation and mean annual temperature played a lesser but still significant role. Overall,
woody vegetation was a poor surrogate, especially for millipedes which have several localized
endemics. The use of higher taxa (genus and tribe in particular) shows the greatest potential for
conservation planning. The current zonation of the Vhembe Biosphere Reserve performed
significantly better than expected in representing invertebrate diversity across the region. The
reality though is that conservation decision-making is largely informed by knowledge on the
distribution of rare, localized or endangered species, for which detailed species inventories are
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required. Though a coarse filter approach is recommended, the augmentation of species level data
provides an extra filter, and contributes to our knowledge of what taxa are in urgent need of
protection. Targeting rare and endangered species in transition zones and developing conservation
assessments and plans for these in relatively small areas would compliment existing conservation
initiatives in the VBR. Annotated check lists ofTenebrionidae of the Vhembe Biosphere suggest
that the family is particularly speciose, the assemblage being comprised of an east African and a
Kalahari element which contributes significantly to local endemicity, and yielded three new
species, one of which is described in the revision to the genus Anaxius, a group largely restricted
to the mountainous areas of Limpopo Province. Carabidae were also found to be speciose, with
the assemblage comprised of a large proportion of stenotypic species. There is support for the use
of vegetation types in conservation plans but these should be augmented with species level
conservation initiatives that target particularly transition and buffer zones.
