Morphological differences and classifications of small spines of puffer fishes

The differences among the small spines of 6 species of puffers have been clarified by means of microscopic observation. Small spines of puffers arise from the basement, which is composed of spines protruding from the surface skin, with roots extending horizontally in all directions in the layer under the surface skin. Using the characteristic shapes of the basement, we have classified the puffer group of 'Sansaifugu' (Takifugu flavidus) and 'Mefugu' (T. obscurus) as Type I and the group of 'Shirosabafugu' (Lagocephalus wheeleri) 'Kurosabafugu' (L. gloveri) 'Dokusabafugu' (L. lunaris) and 'Motosabafugu' (L. spadiceus) as Type II. The number of fore and back roots, including the branches at the ends, further varies in each group. The length and width of each root were measured. As a result, similar species within the group comprising 'Sansaifugu' (T. flavidus) and 'Mefugu' (T. obscurus) and 4 species of the 'Sabafugu' (Lagocephalus) group including 'Dokusabafugu' (L. lunaris) have been clearly distinguished. We conclude that examination of the shape of the basement of small spines can be an effective identification index.