Trypanorhynchid cestodes of commercial inshore fishes of the West African coast

A wide spectrum of fish hosts in the Gulf of Guinea was examined for infestation with trypanorhynchid cestodes. A total of 1341 specimens belonging to 45 species were examined. The following 9 trypanorhynchid species were identified: Callitetrarhynchus gracilis, Grillotia perelica, Nybelinia sp., Otobothrium cysticum, O. dipsacum, Otobothrium sp., Poecilancistrum caryophyllum, Ptero-bothrium sp. and one unidentified species. The pattern of occurrence of Callitetrarhynchus gracilis has been used to draw conclusions on a possible 4-host life cycle of the species, involving two obligatory teleost host fish species, small clupeids and large predatory fish. The most abundant parasite was O. cysticum which was found in 8 host fishes. In general most other species occurred in one host fish species only. The study confirms the predominance of otobothriid cestodes in the parasite fauna of tropical and subtropical teleost fish species. Since only Pseudotolithus senegalensis and Stromateus fiatola harboured flesh infestations, trypanorhynchids do not pose serious dangers to the marketability of most commercially important fish species in the area. The method of scanning electron microscopy was used to clarify the details of hooklet arrangement on the tentacular armature of some species for the first time.