Morphological divergence between two color morphotypes of Crystallichthys matsushimae (Cottoidei: Liparidae)

Abstract

Differences in distributional range and morphological characters between two color morphotypes of a snailfish, Crystallichthys matsushimae, were investigated. Specimens with yellow stripes (yellow morphotype) were collected only from southern part of the Sea of Japan, whereas those with rounded red markings (red morphotype) were collected from northern part of the Sea of Japan, the southern Sea of Okhotsk and the Pacific coast of northern Japan. Although principal component analysis based on 24 morphometric characters did not result in clear separation of the two color morphotypes, the combination of anal and pectoral-fin ray counts clearly distinguished them. These differences in distributional ranges and counts suggest that the two color morphotypes represent two difference species or subspecies, although some differences in measurements and counts among local populations (northern Sea of Japan, southern Sea of Okhotsk and Pacific coast of northern Japan) of the red morphotype were also evident. Because snailfishes usually bear large demersal eggs and have no planktonic stage, the results suggested that migration among local populations is probably restricted due to their low dispersal ability.