The Cichlid Fishes of Lake Malawi, Africa

Abstract of Doctoral Dissertation

Matthew R. Lisy
Pennsylvania State University, 2006
Adviser: Jay R. Stauffer, Jr.  

Systematics and bower-building behavior of the Tramitichromis Eccles and Trewavas (Teleostei: Cichlidae) from the southeast arm of Lake Malawi, Africa  

The Malawians derive 70% of their consumed animal protein from fish from Lake Malawi. It is the goal of the Malawi government to preserve and conserve this resource, but effective fishery management plans cannot be developed because species descriptions are still lacking. Part of my research focused on fish identified as Tramitichromis (an important food fish) in the southeast arm of Lake Malawi. Based upon suggestive evidence in a collection of works (see bibliography in this thesis) by Konings, Turner, numerous publications by Stauffer along with various other authors, and personal communications of Konings and Stauffer, I hypothesized that there were at least three undescribed species.

Collections of fish from the Pennsylvania State University and the Museum of Natural History, London were examined. I examined each collection in the laboratory and reexamined the identity of the fish based on the keys in Tramitichromis [sic]. A subset of fish was chosen out of each collection and lower pharyngeal bones dissected, and then used to verify the species. Fishes that could not be identified were grouped together based on some phenotypic character(s). Twenty-four morphometric and fourteen meristic data points were collected per fish. Differences in body shape were analyzed using sheared principal components analysis (SPCA) of the morphometric data. Differences among species were illustrated by plotting the sheared components of the morphometric data against the principal components of the meristic data in order to maximize the amount of separation. If the mean multivariate scores of the clusters formed by the plots were significantly different along one axis, independent of the other axis, a Duncanís multiple range test (p<0.05) was used to determine which clusters differed from each other. If not, then a MANOVA, in conjunction with a Hotelling-Lawley trace, was used (p<0.05).

Collections in the 1920s and 1930s allowed Trewavas to describe many new species of Lethrinops and place Haplochromis brevis into the Lethrinops based on buccal dentition. In 1935, Trewavas added one new species, Lethrinops intermedia. In 1989 Eccles and Trewavas placed all Lethrinops that possessed a keel into Tramitichromis. Tramitichromis is rediagnosed by the presence of a solid diagonal band that runs from the nape to the caudal peduncle, a significantly different body shape (e.g. a shorter caudal peduncle, longer vertical eye diameter, longer lower jaw, and fewer gill rakers on the outer ceratobranchial), and the use of a rock in cone shaped bowers constructed by breeding males. Tramitichromis brevis is retained in the genus. The remaining species currently in Tramitichromis are moved to a new genus. Six previously undescribed species that have variations in their lower pharyngeal bone, body pattern, and/or shape are described.

Bower building is the manifestation of a behavioral trait and is being used to diagnose species. Another research objective was to determine if it was possible to test bower-building behavior in a laboratory setting, and give comments and suggestions for future research. I had also hoped to provide some anecdotal evidence of the heritability of bower building. Comparisons to an analysis of a previous bower building study showing overlap between genetic and bower (behavioral) data were made as well. A new study for three of the new species was conducted which showed a different bower shape for each of the three species. This is significant because it supports the use of the bower building behavior as a taxonomic tool and shows correlation between morphological data and bower building (behavioral) data. Comments on the feasibility of laboratory studies of bower building are made where it was determined that an extremely large pool was needed with a high stocking density and a ratio of 7 males to 2 females.




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