A review of the anatomy of Polypteridae (Vertebrata: Cladistii).

Author(s)

Pedro Pereira Rizzato

• Document type: Doctoral Thesis
• Press: Ribeirão Preto.
• Institution: Universidade de São Paulo (USP). Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto (PCARP/BC)
• Defense date: 2019-03-15

Examining board members

Flávio Alicino Bockmann; Ricardo Macedo Corrêa e Castro; Fábio Di Dario; Alessio Datovo da Silva

• Advisor: Flávio Alicino Bockmann

Abstract

Polypteridae is a group of freshwater and brackish water fishes currently ocurring exclusively in tropical regions of Africa. The 14 extant species of polypterids are distributed in two genera, Polypterus (bichirs, 13 species) and Calamoichthys (the reedfish, C. calabaricus). The group attracts special interest of researchers due to their peculiar anatomy that combines features observed in different groups of living and extinct vertebrates with exclusive characters such as the presence of a unique type of dorsal fin. The singular combination of characteristics difficults establishing the phylogenetic position of polypterids, although they are considered nowadays the sister-group of all living ray-finned fishes, occupying a key phylogenetic position among the bony fishes. In this context, understanding in details their anatomy is crucial for understanding the evolutionary history of vertebrates as a whole and particularly of bony fishes. The present study consists of a revisionary investigation of the anatomy of polypterids, emphasizing underexplored mophological systems and complexes such as the laterosensory and musculoskeletal systems, on a holistic approach. We integrate the analysis of living specimens, specimens preserved in collections (ethanol-preserved and dry-skeleton preparations), stained and dissected specimens, radiographs, and tridimensional models generated by computadorized tomography. The analysis focuses on the Senegal Bichir, Polypterus senegalus, but includes several specimens of different sizes of all species of polypterids, including types of almost all of them. We include information from early ontogeny, with basis on an analysis of developmental series of P. senegalus and of representatives of the remaining groups of non-teleost actinopterygians (Acipenseriformes, Lepisosteiformes and Amiiformes). The study also includes an extensive revision of the literature on the anatomy and phylogenetic relationships of polypterids and other basal bony fishes. We provide several new interpretations about the anatomy of polypterids and other bony fishes, many of which are incorporated into new proposals of anatomical terminology for Actinopterygii or for Osteichthyes. We also provide a detailed analysis of the intra- and interspecific variation on the external anatomy of polypterids that will be useful in future attempts to unravel their taxonomy and phylogenetic interrelationships. The present study demonstrates that, even considering all the efforts by previous authors, there is still a lot to be known regarding the anatomy of polypterids, as well as of other basal groups of bony fishes. Much of this information can be incorporated into phylogenetic studies in order to improve our hypotheses of evolutionary relationships between the major clades of Vertebrata, and can also provide new ideas about the anatomy and evolutionary history of vertebrates. (AU)

• FAPESP's process: 14/10849-6 - Anatomic atlas of Polypteriformes: a comparative analysis of basal gnathostomates
• Grantee: Pedro Pereira Rizzato
• Support Opportunities: Scholarships in Brazil - Doctorate