ハリゴチ科魚類の近似三種間にみられる種性及び成長段階的形態変異について

Abstract

The morphological variations dependent on the species, sex, and growth stages are researched in three approximate species of the family Hoplichthyidae (Hoplichthys gilberti JORDAN and RICHARDSON, H. langsdorfii CUVIER and VALENCIENNES and H. fiiamentosus MATSUBARA and OCHIAI). In this research, the auther particularly remarked the following body parts: trunk length, dorsal spine length, dorsal soft ray length and pectoral fin length, which are all distinctly variable with species, sex, and growth stages. The results obtained are summalized as follows (Table 1). 1. The sexal dimorphism displays in all Hoplichthys in the same characters, such as trunk length, dorsal first spine length and dorsal first soft ray length. 2. There appears the tendency toward parallelism in the observed differences between sexes and also between growth stages, among all species through these characters. 3. The morphological differences dependent on sexes and growth stages run parallelld with those between two species, H. gilberti and H. filamentosus. H. gilberti differs from H. fiiamentosus in the same way that the male differs from female, or the old from the young. But these parallelism can not be found between H. gilberti and H. langsdorfii, nor between H. langs-dorfii and H. fiiamentosus. 4. The specific differences are shown in the elongate conditions of dorsal soft rays of the male fishes which begin to mature (Fig. 6). H. gilberti diverges into two types in characters of soft dorsal fin. In one type, which is called herein as type A, the fourth to seventh soft rays are filamentous, whereas eighth to fourteenth are not longer than the first ray. The other type, which is called type B, is characterized by the length of second to thirteenth or fourteenth soft rays, which are longer than the first ray. In H. langsdorfii some anterior soft rays are filamentous and eighth to fourteenth rays are longer than the first ray. In H. filamentosus. all dorsal soft rays are filamentous, which is the peak of the differentiation of this character. The pattern of these processes in differentiation is shown in Fig. 7.