The Evolutionary biology and taxonomic review of Zambian riverine haplochromine cichlids
Date
2012-11-01
Authors
Katongo, Cyprian
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Abstract
This study aimed at reconstructing the phylogenetic relationships among Zambian riverine haplochromine cichlids and at reviewing their taxonomic status. The riverine haplochromines used were from the Zambezi River and the Luapula-Congo River systems. The target taxa were from two major groups: the Serranochromine species and the Pseudocrenilabrus species complex. Phylogenetic studies were based on mitochondrial DNA sequence analysis while the taxonomic studies were based on principal component analysis (PCA) of morphological characters. The results indicate that the Zambian riverine haplochromines share a common ancestor, which is likely to have originated from the Congo drainage and later colonized the Zambezi drainage. The results also indicate a need to revise the genera Serranochromis, Sargochromis, Pseudocrenilabrus and Pharyngochromis from all the rivers of Zambia. There are likely to be a number of undescribed species and/or misidentifications within these genera. There might be at least 3 species of Pseudocrenilabrus in Zambia. The Pseudocrenilabrus 'sp haplochromis-orange' population from the Lake Mweru / Mwatishi River confluence is morphologically the most distant from the other populations. Some of the Pseudocrenilabrus species from Luc de Vos' collection from the Lufubu River drainage, held in the Royal Museum of Central Africa at Tervuren, Belgium (MRAC 96-031-P and MRAC 96-083-P) may be members of a new species. The Sargochromis specimens from the Luapula, collected by Van Zwieten (MRAC 9-035-P) and those collected during this study (MRAC A4-25), both held at the Royal Museum of Central Africa, appear to consist of two morpho-types with one of them likely to be Sargochromis mellandi while the second is likely to be different. There seem to be two or more undescribed species of Sargochromis- collected from the Kafue River. One of them, a slender type with a long snout (Sargochromis 'sp longsnout-kafue'), was quite abundant during the field fcrjp of the summer of 2002, while another one with longitudinal stripes Hvas less abundant (Sargochromis 'sp striped'). Van der Waal's collection (RUSI 062863) has one Sargochromis species collected from below the Itezhi tezhi Dam, on the Kafue River. This taxon (Sargochromis 'sp Zambia') is very likely to be a new record in the Kafue system or even an undescribed species. The Pharyngochromis group seems to consist of at least more than one species. The Pharyngochromis acuticeps from Lake Kariba fits very well into the description of Skelton (1993) and Greenwood (1992). The other Pharyngochromis individuals are generally bigger in size with a different coloration on the head. There seem to be some individuals, which are intermediate between Sargochromis and Pharyngochromis from the Upper Zambezi. There was one Serranochromis 'sp elongate', collected from Lake Mweru, which is morphologically similar to (but does not fit into the description of) either S. macrocephalus or S. stappersi, which have both been documented in that lake. It has a close mitochondrial phylogenetic relationship with Serranochromis angusticeps.
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Keywords
Cladistic analysis , Evolution (Biology)