The Cichlid Fishes of Lake Malawi, Africa

Abstract of Doctoral Dissertation

Michael Kenneth Oliver
Yale University, 1984
Adviser: Keith S. Thomson  

Systematics of African cichlid fishes: Determination of the most primitive taxon, and studies on the haplochromines of Lake Malawi  

The cichlids of Africa present many challenges to the taxonomist. Diverse systematic problems at three levels in cichlid phylogeny form the subject matter of this dissertation. At the most general level, I summarize current morphological evidence that supports cichlid monophyly and the most-inclusive groups of cichlids. With this review as a framework, I argue that the most phylogenetically primitive African cichlid is Heterochromis multidens, a little-known large cichlid from the Zaire River basin. I redescribe this monotypic genus and species and illustrate much of its osteology. It possesses a distinctive suite of derived characters, but is uniquely primitive among African cichlids in infraorbital morphology and other features.

At a less inclusive phylogenetic level, I examine the controversy over the monophyletic status of the "species flock" of haplochromine cichlids in Lake Malawi. A derived type of anal-fin markings present in a subset of the Malawian fauna is shared with many non-Malawian haplochromines, indicating that the species flock of Lake Malawi is not monophyletic. The two (or more) faunal components of Lake Malawi are ecologically distinct.

The remaining major parts of the study are concerned with particular assemblages of haplochromine cichlids in Lake Malawi. I present a detailed phylogenetic analysis of the Cyrtocara livingstonii species-group of ambush predators, and characterize a new species in the group. I also describe three new species of haplochromines with three lateral spots and present a key to the three-spot assemblage. Intralacustrine dispersion of Malawi cichlids is briefly addressed in appended material.




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