The Pennsylvania State University The Graduate School College of Agricultural Sciences TAXONOMIC STUDY OF THE GENUS PETROTILAPIA TREWAVAS 1935 (TELEOSTEI: CICHLIDAE) FROM LAKE MALAŴI, AFRICA A Dissertation in Wildlife and Fisheries Science by Mary Lundeba © 2009 Mary Lundeba Submitted in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy August 2009 The dissertation of Mary Lundeba was reviewed and approved* by the following: J.R. Stauffer Jr. Distinguished Professor of Ichthyology Dissertation Advisor Chair of Committee Graduate Program Chair Cecilia Paola Ferreri Associate Professor of Fisheries Management Walter M. Tzilkowski Associate Professor of Wildlife Science Ke Chung Kim Professor of Entomology and Curator Emeritus; Director Emeritus, Center for Biodiversity Research Adrianus Konings Special Signatory Proprietor of Cichlid Press, Texas * Signatures are on file in the Graduate School. ii ABSTRACT Lake Malaŵi is the southernmost of the East African Rift Lakes and harbors about 850 cichlid species of which less than 500 have been scientifically described. One of the genera of cichlid fishes is Petrotilapia, which contains the largest mbuna (rock- dwelling cichlids) of Lake Malaŵi. Petrotilapia species are characterized by broad fleshy lips that are densely covered with slender teeth that are visible even when the mouth is closed. The members of the genus Petrotilapia have been divided into three groups namely the P. tridentiger, the P. genalutea, and the P. nigra group. The members of the P. tridentiger group are mainly found in the wave-washed upper rocky habitats, while those of the P. genalutea group inhabit the sediment-rich and intermediate habitats. The P. nigra group contains the largest number of species that inhabit the deeper rocky environments; this group prefers sediment-free rocky habitats. The three Petrotilapia groups are also distinguished by female melanin pattern. The pattern in females of the P. tridentiger group consists of indistinct vertical bars. Females of the P. genalutea group are characterized by two rows of spots on the flank, with the lower row consisting of a few large blotches. Females of P. nigra group often have a yellow or golden background color and a pattern consisting of two horizontal rows of dots of about the same size, with the ones of the mid-lateral row slightly larger. A pattern of, sometimes indistinct, vertical bars is superimposed on the two horizontal rows of dots. Five hundred and sixty newly collected Petrotilapia specimens were evaluated. New species of Petrotilapia were diagnosed and described by investigating morphological and meristic differences among populations. Petrotilapia populations were compared on the basis of locality, species complex (Petrotilapia tridentiger, iii Petrotilapia genalutea, or Petrotilapia nigra group), and markings (presence or absence of a black band in the dorsal fin). Differences in morphology were analyzed using sheared principal component analysis (SPCA) of the morphometric data and principal component analysis of the meristic data. Differences among species were illustrated by plotting the second sheared components of the morphometric data against the first principal component of the meristic data 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, a Duncan Multiple Range Test (DMRT) (p<0.05) was used to determine which clusters differed from each other. If the clusters were not significantly different along either axis, then a multivariate analysis of variance (MANOVA), in conjunction with a Hottelling-Lawley trace was used (p<0.05). Five populations of Petrotilapia were found to be different from all other populations as well as from described species and were described as new species. Newly described species include Petrotilapia xanthos from Gallireya Reef, Petrotilapia mumboensis from Mumbo and Thumbi West islands, Petrotilapia pyroscelos from Mkanila Bay, Chizumulu Island, Petrotilapia flaviventris from Same Bay, Chizumulu Island, and Petrotilapia palingnathos from Mkanila Bay, Chizumulu Island; this brings the total to 10 described Petrotilapia species. I determined Petrotilapia ‗ruarwe‘ from Kakusa and Mbowe Island as conspecifics with Petrotilapia microgalana from Nkhata Bay. There was no morphological difference between Petrotilapia sp. ‗mumbo yellow‘ from Mumbo Island and P. nigra from neighboring Thumbi West Island. I, therefore, considered P. sp. ‗mumbo yellow‘ a geographical variant of P. nigra. There may be five more undescribed species in the genus Petrotilapia. iv TABLE OF CONTENTS LIST OF FIGURES .......................................................................................................... vi LIST OF TABLES ............................................................................................................. ix ACKNOWLEDGEMENTS ................................................................................................ x Chapter 1 ............................................................................................................................. 1 Introduction ..................................................................................................................... 1 Study goal and objectives………………………………………………………………4 Cichlid phylogeny, speciation, and diversity…………………………………………...5 Stages of evolutionary cichlid radiation………………………………………………..8 Historical review of Petrotilapia .................................................................................. 13 Species concepts and criteria used to delimit species of Petrotilapia………………...16 Chapter 2…………………………………………………………………………………20 Materials and Methods .................................................................................................. 20 Chapter 3…………………………………………………………………………………29 Description of Petrotilapia ........................................................................................... 29 Generic description ................................................................................................... 29 Genus Petrotilapia Trewavas, 1935 ......................................................................... 29 Petrotilapia tridentiger Trewavas (1935) ................................................................. 31 Petrotilapia genalutea Marsh (1983) ........................................................................ 35 Petrotilapia nigra Marsh (1983) ............................................................................... 39 Petrotilapia chrysos Stauffer and Van Snik (1996) .................................................. 43 Petrotilapia microgalana Ruffing, Lambert, and Stauffer (2006) ........................... 47 New species of Petrotilapia .............................................................................................. 52 Petrotilapia xanthos n. sp. (Fig. 12) ........................................................................ 52 Petrotilapia mumboensis n. sp. (Fig. 18) .................................................................. 63 Petrotilapia pyroscelos n. sp. (Fig. 21)..................................................................... 71 Petrotilapia flaviventris n. sp. (Fig. 24) .................................................................... 79 Petrotilapia palingnathos n. sp. (Fig. 27) ................................................................. 87 Chapter 4 ........................................................................................................................... 94 Discussion and conclusion ............................................................................................ 94 Chapter 5 ........................................................................................................................... 96 Taxonomic key to the Species of Petrotilapia: Species Identification………………......96 Key to described species of Petrotilapia ................................................................. 97 Literature Cited ............................................................................................................... 102 v LIST OF FIGURES Figure 1: Illustration of the three stages of evolutionary vertebrate radiation from Lake Malaŵi, Africa ………………………………………………………….………….10 Figure 2: A member of the genus Petrotilapia from Lake Malaŵi, showing visible teeth while mouth is closed, a key diagnostic feature. ...................................................... 14 Figure 3: Lake Malaŵi: showing some localities of Petrotilapia species ........................ 24 Figure 4: Illustration of some of the morphometric and meristic data points ................... 25 Figure 5: Petrotilapia tridentiger male, Boadzulu Island, Lake Malaŵi, Malaŵi. .......... 32 Figure 6: Petrotilapia genalutea male, Boadzulu Island, Lake Malaŵi, Malaŵi. ............ 36 Figure 7: Petrotilapia nigra male, Thumbi West Island, Lake Malaŵi ........................... 40 Figure 8: Plot of the second sheared principal component (morphometric data) and the first factor scores (meristic data) of Petrotilapia sp. ‗mumbo yellow‘ from Mumbo Island (N = 39); Petrotilapia nigra from Thumbi West (N = 14 PSU 4801; Petrotilapia nigra from Monkey Bay (Holotype) BMNH 1981.2.2:206……………………………………………………………………..48 Figure 9: Petrotilapia chrysos male, Chinyamwezi Island, Lake Malaŵi,. ..................... 44 Figure 10: Petrotilapia microgalana male, Lion‘s Cove (T‘hoto), Lake Malaŵi ...........