African Journal of Aquatic Science

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Phylogenetic relationships between Synodontis species: some preliminary results

EE Bruwer, FH van der Bank, GJ Steyn, M Wink


The aim of this study was to identify genetic markers and morphological characters to distinguish Synodontis species, because certain species are extremely difficult to identify due to the taxonomically unreliable nature of prominent morphological features. Fixed allele mobility differences were obtained at eight of the 17 loci studied. Unique alleles were found at EST(B) in S. zambezensis and LGG(B) in S. nigromaculatus, whereas the outgroup species Parauchenoglanis ngamensis had private alleles at SDH(A), MPI(C) and LGG(A). The species boundaries were tested using controlled breeding studies between S. nigromaculatus and S. zambezensis. A preliminary DNA sequence (781 base pairs) analysis of the mitochondrial cytochrome b gene was done. Synodontis zambezensis, S. nigromaculatus, S. njassae and S. petricola, all with convex humeral processes, were grouped in one clade. The species S. macrostoma, S. macrostigma, S. woosnami and S. leopardinus were grouped together, but with poor resolution. Morphological characters to identify southern African Synodontis species are listed. A more detailed study is required to resolve the phylogenetic relationships of some of the species studied.

Keywords: Synodontis; relationships; DNA sequence; allozymes

(Afr J Aqua Sci: 2000 25: 89-92)
AJOL African Journals Online