沖繩島産ヨシノボリの2型

概要

論文の詳細を見る
The freshwater gobioid fish Rhinogobius brunneus of Okinawa-Jima, Ryukyu Islands was distinguished ecologically and morphologically into two forms, the small-egg type and the medium-egg type. The former, having a large number of small eggs, showed no significant difference from the fish of the same type in Honshu, Japan. The latter was characterized by the size and number of its eggs intermediate between the small eggs of the former and the large eggs of the related species, Tukugobius flumineus which was once classified as a synonym of R. brunneus. In the number of pectoral fin rays, it was also intermediate between the small-egg type and T.flumineus. The newly hatched larva of the medium-egg type was morphologically similar to that of the small-egg type, having a continuous fin fold. While the colour pattern on body sides was similar to T.flumineus. In a stream, the medium-egg type was distributed mainly in the upper courses, and many larvae in their swimming stages were also observed in the same courses of streams. This indicates that the medium-egg type can spend its whole life in a stream, although the larvae in their early stages do not have the properly constituted fins.
社団法人日本動物学会の論文
1968-12-15