Thesis (M.Sc.)--Chulalongkorn University, 2007

The present taxonomic study is the update revision of spiny eels (Synbranchiformes: Mastacemeblidae) found in Thailand. It is based on specimens deposited in local reference collections and newly collected specimens throughout Thailand during June 2006 to September 2007. It represents an attempt to alleviate difficulties with the species identification of individual specimens by providing a treatment of the nomenclature and taxonomy of all available local members. Two genera and twelve species, Macrognathus aculeatus, M. circumcinctus, M. maculatus, M. meklongensis, M. semiocellatus, M. siamensis, M. zebrinus, Mastacembelus alboguttatus, M. armatus, M. erythrotaenia, M. favus and M. tinwini were recognized. All of them are freshwater fish. However M. erythrotaenia can be found in both fresh and brackish waters. Upon this study, M. tinwini is a newly recorded species. The species identification of the family Mastacembelidae is based largely on configurations and the presence or absence of colour markings on body and fins and different numbers of spines, fin rays and vertebrae. The dichotomous keys to genera and to species are provided. The information about the scientific names, synonyms and citations, common names, local names, examined material, diagnosis, descriptions, distribution, habitats, frequency distribution of spines, fins and vertebrae and photographs are available. Morphometric and meristic dendograms using Hierarchical cluster analysis were constructed.