メダカOryzias latipesの骨学的研究

抄録

Recent studies which drastically changed the systematic position of Oryzias latipes stimulated us to investigate and provide complete osteological illustrations and description of the rice fish which has been one of the most popular fishes in Japan.

The important osteological features of Oryzias latipes Temminck et Schlegel include loss of some elements, and specialization in structures related to feeding and sexual dimorphism. Bony elements lost in Oryzias latipes are parietals, prevomer, infraorbital bones, supraorbitals, intercalars, orbitosphenoid, basisphenoid, 1st and 2nd pleural ribs, ectopterygoids, metapterygoids, 1st pharyngobranchials, upper hypohyals, interhyals, supracleithra, mesocoracoids. Morphological specializations include sexual dimorphism in tooth forms: teeth are larger and fewer in male with robust teeth at the posterior end of the premaxillary. Branchial skeletons have special enlargement of 3rd pharyngobranchials and pharyngeal bones. Number of vertebrae is 27–30 with 11–12 abdominal and 16–18 caudal vertebrae.