Karyology of the redfin minnows, genus Pseudobarbus Smith, 1841 (Teleostei: Cyprinidae): one of the evolutionarily tetraploid lineages of South African barbines D. Naran 1* , P.H. Skelton 2* & M.H. Villet 3 1 Department of Ichthyology and Fisheries Sciences, Rhodes University, Grahamstown, 6140 South Africa 2 South African Institute for Aquatic Biodiversity, Private Bag 1015, Grahamstown, 6140 South Africa 3 Department of Zoology and Entomology, Rhodes University, Grahamstown, 6140 South Africa Received 11 April 2003. Accepted 1 December 2005 The karyotypes of six species of Pseudobarbus Smith, 1841, namely P. afer (Peters, 1864), P. asper (Boulenger, 1911), P. burchelli Smith, 1841, P. burgi (Boulenger, 1911), P. phlegethon (Barnard, 1938) and P. tenuis (Barnard, 1938), were examined by conventional Giemsa staining and described. All six karyotypes have 2n = 100 chromosomes, dominated by bi- armed chromosomes, as does the only other member of the genus, P. quathlambae (Barnard, 1938). Sex-related intraspecific karyotype variation was not found. The shared chromosome numbers and general similarity of the karyotypes (FN = 186–192) provide a new synapo- morphy to support their monophyly, which is already indicated by anatomical and mtDNA markers. Karyotype evolution within the genus has been accompanied by chromosomal inver- sions and centromeric shifts. Comparison of the diploid number found in Pseudobarbus with other African barbine cyprinines, which have in the region of 2n = 50 and lower FNs, suggests a tetraploid evolutionary origin of the genus, possibly by allotetraploidy. Key words: Pseudobarbus, Barbinae, tetraploidy, cytogenetics, karyotype INTRODUCTION Cyprinids are a major component of the freshwater ichthyofauna of Africa (Skelton et al. 1991; Skelton 2001). Biogeographically, the southern African representatives have been grouped into temperate (Cape and/or Karoid) and tropical (Zambezian) elements (Skelton 2001). Cyprinids comprise about 80% of the temperate region’s fish fauna, and the majority of these are barbine cyprinines (sensu Howes 1991), placed in the genera Barbus Cuvier & Cloquet, 1816, Pseudobarbus Smith, 1841, Labeobarbus Rüppel, 1836, and Labeo Cuvier, 1817 (Skelton et al. 1991; Skelton 1994, 2001). The available karyological studies showed that these African barbine lineages include three ancestral ploidy levels: diploid (e.g. Wolf et al. 1969; Ráb et al. 1995; Golubtsov & Krysanov 1993; Naran 1997); tetraploid (Naran 1997); and hexaploid (Oellermann & Skelton 1990; Golubtsov & Krysanov 1993; Guégan et al. 1995; Krysanov & Golubtsov 1996; Naran 1997; Berrebi & Ráb 1998). The first data on the phylogenetic relation- ships, based on mtDNA markers (Machordom & Doadrio 2001; Tsigenopoulos et al. 2002) suggest several conclusions. First, the genus of ‘true’ Barbus s. str. is tetraploid and is confined to the European region (Berrebi et al. 1996; Tsigenopoulos & Berrebi 2000); African species still assigned to the genus must be transferred to other genera. Second, the genus Labeobarbus, comprising a number of African and Middle Eastern evolu- tionarily hexaploid species, is monophyletic (Machordom & Doadrio 2001; Durand et al. 2002; Gorskova et al. 2002; Tsigenopoulos et al. 2002). Third, the endemic South African genus Pseudo- barbus is monophyletic (Machordom & Doadrio 2001) and may be of evolutionarily tetraploid origin (Oellermann & Skelton 1990). Finally, sev- eral other southern African barbine species (‘B.’ andrewi, ‘B.’ serra, ‘B.’ erubescens, ‘B.’ calidus and ‘B.’ trevelyani) are also tetraploid, but not do not form a monophyletic group, and several new genera should be erected for them (Tsigenopoulos et al. 2002). The genus Pseudobarbus is a distinct lineage of seven species, endemic to temperate South Africa (Skelton 1988). The monophyly of the genus is strongly supported by morphological characters *Authors for correspondence. E-mail: d.naran@ru.ac.za; p.skelton@ru.ac.za African Zoology 41(2): 178–182 (October 2006)