STUDY ON THE GOBIOID FISH, “YOSHINOBORI” Rhinogobius similis GILL-II

COMPARISON OF MORPHOLOGICAL CHARACTERS OF THREE ECOLOGICAL TYPES

Abstract

Succeeding the life history study in the previous paper of three ecological types of “Rhinogobius similis”, the morphological characters of adult fish are compared in the present paper.
In spite of the apparent similarities in the body form, the fluvial type is clearly different from the other two types (the amphidromous and lacustrine types) in the colour pattern on the body side (Fig. 1), and in the number of vertebrae, pectoral and first dorsal fin rays (Table 1; Fig. 2). Considering the more distinctive features in the size and number of mature eggs, in the size and developmental stage of newly hatched larvae as reported in the previous paper, it seems appropriate to conclude that the fluvial type is to be referred to the genus Tukugobius HERRE, 1927 instead of the genus Rhinogobius. The other two types, i. e., amphidromous and lacustrine types have no more distinctions with each other than intraspecific variations (Table 1; Figs. 2 and 3). Thus, the fluvial type is named as Tukugobius flumineus and the other two types retain the customary name Rhinogobius similis GILL.