Abstract
During the midwater trawl survey of the T/V Oshoro-Maru of Hokkaido University, a rare macrourid larva was collected at 0-400m depth in the southeast of the Ryukyu Islands in November 1988. The larva has a discoid pectoral fin with long, stalked base, a feature that identifies it as a macrourid alevin (Merrett, 1989). The structure of the light organ and the presence of seven branchiostegal rays further identifies the specimen as a species of Hymenocephalus.
Information on the early life history of PacificOcean macrourids is available for only four speciesof two genera, Coryphaenoides and Mesobius (Gilbertand Burke, 1912; Hubbs and Iwamoto, 1977;Stein, 1980). In this paper, we report the first discoveryfrom the Pacific Ocean of an alevin of Hymenocephalus.
The specimen was fixed and preserved in 5% buffered formalin, and is deposited in the larval collection of the Laboratory of Marine Zoology, Faculty of Fisheries, Hokkaido University (HUMZ-L). Methods for taking meristic and morphological data follow Stein (1980) and Merrett (1989). Terminology for life history stages follows Merrett (1989).
