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ANOSTRACANS (BRANCHIOPODA) OF BOTSWANA: MORPHOLOGY, DISTRIBUTION, DIVERSITY, AND ENDEMICITY

1997; Oxford University Press; Volume: 17; Issue: 1 Linguagem: Inglês

10.1163/193724097x00151

1937-240X

Luc Brendonck, Bruce Riddoch,

Marine Biology and Ecology Research

Including the present update, 14 anostracan species, belonging to Streptocephalus (8), Branchipodopsis (3), and Branchinella (3) are currently reported from Botswana. Branchinella spinosa and Branchipodopsis kalaharensis are the only species not occurring in neighboring southern African countries, with only the latter being a true endemic to Botswana. Streptocephalus cf. bidentatus and S. cf. cladophorusldendrophorus, distinct morphs close to the South African S. bidentatus, and to both S. dendrophorus and S. cladophorus, respectively, are additions to the fauna of Botswana, but are not given specific status. Branchinella ondonguae is also reported for the first time from Botswana. Higher species richness (33) and endemicity (64%) in South Africa are attributed to greater habitable surface area, topographic and environmental heterogeneity, and research effort. A high degree of overlapping ranges of cognate species is observed, and 2 pairs of sister species (Streptocephalus macrourus/S. cf. bidentatus and S. cafer/S. indistinctus) were found in syntopy. The occurrence of specimens with intermediate or odd morphology in the presence of, or in the area of overlap of, supposed parental species, suggests natural hybridization between S. cafer X S. indistinctus, and between S. macrourus × S. cf. bidentatus. No species were found in areas with less than 350 mm of mean annual rainfall. Species of Branchipodopsis are the only anostracans in often clear, short-lived rock pools. Expanding agricultural and mining industries, roadworks, together with inappropriate conservation management, are the most important threats to the temporary pool habitats in Botswana.