Mature spermatozoa of two perciform teleost fishes, Paraupeneus spilurus (Mullidae) and Siganus fuscescens (Siganidae) from Taiwan were examined using transmission and scanning electron microscopy. Despite the fact that spermatozoa of both species are of the primitive type, the results of the present study highlight the potential application of spermatozoal morphology in studies of fish phylogenetic relationships. To our knowledge, the flattened nucleus observed in P. spilurus spermatozoa is reported for the first time. Several features common to Sigandae spermatozoa-the unusual almost parallel situation of the centrioles, the arrangement of mitochondria and the near absence of shallow nuclear fossa-are significantly different from other common teleost sperm types. These unique features may be synapomorphies for the Siganidae and Mullidae and evidently contribute to the study of phylogenetic relationships in teleosts. (C) 2003 Elsevier Ltd. All rights reserved.
