STUDIES ON THE DEVELOPMENT OF THE CRAB PUGETTIA QUADRIDENS (DE HAAN) : 1.HATCHING AND ZOEAE

Abstract

Among the Brachyuran larvae recorded from Japan (AIKAWA '29, '33, '35, '37, '41; TAKEDA and MIYAKE '68), the first zoea of Pugettia quadridens (BRACHYURA, Majidae) has been described by AIKAWA ('29, p. 38 and 39), who obtained the larvae from the berried crabs. In the winter of 1969, the present writer had a chance to observe the development of P. quadridens collected on the Pacific coast of the southwestern Hokkaido, North Japan, and came to a conclusion that his first zoea obtained shows many differences in structure in comparison with that of AIKAWA. As the crabs studied by AIKAWA were collected on the Pacific coast of the southern Kanto District, .Middle Japan, the differences between the characters of the bot~ larvae may be either due to the environmental or to the genetical differences. The present paper deals with the development of Pugettia quadridens from northern Japan, especially regarding the hatching of eggs and characters of the pre- and first zoea. The crabs for the present observation are stocked in the Zoological Institute, Faculty of Science, Hokkaido University, Sapporo, Japan. Before going further, the writer wishes to express his cordial thanks to Prof. emer. Dr. Tune SAKAI, Faculty of Education, Yokohama National University, Yokohama, for his kind suggestions on the identification of the present species. Thanks are also due to Prof. emer. Dr. Tohru UCHIDA for his kindness to read through the manuscript.