STIJN DEVAERE Taxonomy and Evolutionary Morphology of African Catfishes (Clariidae), Roads to Anguilliformity I – Text
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Faculteit Academiejaar Wetenschappen 2004/2005 Vakgroep Biologie Taxonomy and evolutionary morphology of African catfishes (Clariidae), roads to anguilliformity I – Text ? STIJN DEVAERE Thesis submitted to obtain the degree of Rector: Prof. Dr. A. De Leenheer Doctor in Sciences (Biology) Decaan: Prof. Dr. L. Moens Proefschrift voorgedragen tot het bekomen van de graad van Doctor in de Promotor: Prof. Dr. D. Adriaens Wetenschappen (Biologie) Co-Promotor: Prof. Dr. W. Verraes MEMBERS OF THE EXAMINATION COMMITTEE Prof. Dr. WIM VYERMAN, Chairman (UGent, BE) Prof. Dr. DOMINIQUE ADRIAENS, Promotor (UGent, BE) Prof. Dr. WALTER VERRAES, Co–Promotor (UGent, BE) Dr. JEAN–FRANÇOIS AGNESE (Université de Montpellier, FR) Prof. Dr. JOS SNOEKS (MRAC, BE) Dr. ERIK VERHEYEN (KBIN, BE) Prof. Dr. ANN HUYSSEUNE (UGent, BE) Prof. Dr. LUC LENS (UGent, BE) Dr. PETER WEEKERS (UGent, BE) Nothing has such power to broaden the mind as the ability to investigate systematically and truly all that comes under thy observation in life. Marcus Aurelius All truths are easy to understand once they are discovered; the point is to discover them. Galileo Galilei Contents I Contents PART I – General Introduction I.1 - History and Aims ................................................................................1 I.1.1 History ................................................................................. 1 I.1.2 Aims .................................................................................... 4 I.1.3 Structure of this thesis.............................................................. 5 PART II – Taxonomic overview II.1 – Catfishes, a group of specialised Ostariophysi ............................................6 II.1.1 Ostariophysi .......................................................................... 6 II.1.1.a The Ostariophysi within the Teleostei ...........................6 II.1.1.b Ostariophysan characteristics ....................................7 II.1.1.c Ostariophysan affinities...........................................9 II.1.1.d Ostariophysan zoogeography ................................... 11 II.1.2 Siluriformes ........................................................................ 12 II.1.2.a Some catfishes specialisations ................................. 12 II.1.2.b Affinities between catfishes.................................... 15 II.1.2.c Siluriform zoogeography ........................................ 17 II.1.3 Clariidae ............................................................................ 18 II.1.3.a Some clariid specialisations .................................... 19 II.1.3.b Clariid composition ............................................. 20 II.1.3.c Affinities within the Clariidae .................................. 21 PART III – Material and Methods III.1 – Material ....................................................................................... 26 III.2 – Methods ....................................................................................... 34 III.2.1 Preparation of living specimens................................................ 34 III.2.1.a Anaesthesia and Sacrifice ..........................................34 III.2.1.b Fixation ...............................................................34 III.2.2 Morphological descriptions...................................................... 34 III.2.2.a In toto clearing and staining.......................................35 III.2.2.b Dissections............................................................35 III.2.2.c Serial sections........................................................36 III.2.3 Visualisation....................................................................... 36 Contents II III.2.3.a Camera lucida........................................................36 III.2.3.b CT–scanning (IV.3.1 G. nops) ......................................36 III.2.3.c Radiographs...........................................................36 III.2.4 Biometric and Morphometrical analysis....................................... 37 III.2.4.a Biometric measurements...........................................37 III.2.4.b Meristic................................................................39 III.2.5 Statistical analyses............................................................... 39 III.3 – Some Terminologies used .................................................................. 42 PART IV – Morphology and species demarcation of the anguilliform clariids IV.1 - The genus Platyallabes..................................................................... 44 IV.1.1 Morphology and spatial constraints in a dorso-ventrally flattened skull, with a revised species description of Platyallabes tihoni (Poll, 1944). .................................................................................... 44 IV.2 - The genus Platyclarias ..................................................................... 62 IV.2.1 Morphology of the cranial system of Platyclarias machadoi Poll, 1977: interdependencies of skull flattening and suspensorial structure in Clariidae .............................................................................. 62 IV.3 - The genus Gymnallabes .................................................................... 83 IV.3.1 Holotype skeletal morphology of Gymnallabes nops Roberts and Stewart, 1976, using micro CT-scanning ........................................... 83 IV.3.2 Gymnallabes typus ............................................................... 99 IV.4 - The genus Dolichallabes ..................................................................102 IV.4.1 Redescription of Dolichallabes microphthalmus Poll, 1942 (Siluriformes, Clariidae) ............................................................. 102 IV.5 - The genus Channallabes ..................................................................112 IV.5.1 The Congo River specimens.................................................... 112 IV.5.1.a Cranial morphology of the anguilliform clariid Channallabes apus (Günther, 1873) (Teleostei: Siluriformes): are adaptations related to powerful biting? ..............................................112 IV.5.1.b A survey of the anguilliform Clariidae of the Congo River basin, with the description of a new species...........................132 IV.5.2 The non Congo River Specimens .............................................. 143 IV.5.2.a A survey of the anguilliform Clariidae of the Central and Southern West Coastal Equatorial freshwater ecoregions (Gabon and Republic of the Congo); with the description of two new Contents III species, including a new, complete key of the African Clariidae genera ...................................................................143 PART V – Phylogenetic Analyses V.1 - Molecular Phylogeny........................................................................163 V.1.1 Phylogenetic and biogeographic analysis of air-breathing catfish (Siluriformes: Clariidae) inferred from ribosomal gene and spacer sequences, with an emphasis on anguilliformity................................. 163 V.2 – Combined, morphological and molecular phylogeny ..................................179 V.2.1 Phylogeny of the African catfish family Clariidae (Siluriformes) based on morphological and combined analyses: the road to anguilliformity ......................................................................... 179 PART VI – General discussion VI.1 - Consequences of the generated phylogeny (based on the consensus tree of the combined analysis) ..................................................................198 VI.2 - Encountered taxonomic problems .......................................................202 VI.2.1 Single specimen species........................................................ 202 VI.2.2 Sub–(species) ..................................................................... 204 VI.3 - Morphological versus molecular data, which is the best?............................207 PART VII – Conclusions and Summary VII.1 - Conclusions and Summary................................................................213 VII.2 - Conclusies en Samenvatting .............................................................217 PART VIII – References VIII.1 - References.................................................................................222 Appendix I .............................................................................................240 Acknowledgements - Dankwoord IV Acknowledgements – Dankwoord Dit dankwoord is één van de laatste dingen die ik heb geschreven, maar daarom is het zeker niet het minst belangrijke deel uit dit proefschrift. Als ik na bijna zes jaar eens terug kijk, dan zijn er verscheidene mensen die ik wil bedanken. Met het risico dat ik enkele vergeet, zou ik toch volgende personen eens uitdrukkelijk willen bedanken, die op verschillende manieren hebben bijgedragen tot dit werk. Uiteraard komen mijn promotor, co-promotor en begeleider (de link tussen titel en persoon bleek nogal eens te wijzigen) op de eerste plaats in dit lijstje. Prof. Dr. Walter Verraes wil ik bedanken om mij via zijn labo kennis te hebben laten maken met de “wondere wereld” van de Afrikaanse katvissen. Nooit gedacht toen ik begon met mijn thesis, dat ik bijna zes jaar later nog altijd op dezelfde vissen zou werken. Wijlen Prof. Dr. Guy Teugels zou ik willen bedanken om mijn eerste pasjes in de systematiek, taxonomie en fylogenie te begeleiden. Ik heb ook veel opgestoken van onze discussies gaande van de criteria van soorten en ondersoorten tot de troeven