Species Diversity, 2007, 12, 17–27

Pelagic Juveniles of Two Morids (Teleostei: : ), microlepis and , from the Western North Pacific

Makoto Okamoto1, Naoshi Sato2, Takashi Asahida2 and Yoshiro Watanabe3

1 Tohoku National Fisheries Research Institute, 3-27-5 Shinhama-cho, Shiogama, Miyagi, 985-0001 Japan E-mail: [email protected] 2 School of Fisheries Sciences, Kitasato University, 160-4 Okirai, Sanriku-cho, Ofunato, Iwate, 022-0101 Japan 3 Ocean Research Institute, University of Tokyo, Minamidai, Nakano-ku, Tokyo, 164-8639 Japan

(Received 1 July 2006; Accepted 20 November 2006)

Pelagic juveniles of two morids, Antimora microlepis Bean, 1890 and Physiculus japonicus Hilgendorf, 1879, were collected by midwater trawl (0–20 m depth) from transition waters between the Oyashio and Kuroshio fronts of the western North Pacific in May, 1989. Juveniles of A. microlepis (13 specimens, 30.2–54.3 mm standard length, SL) characteristically have an elongated body, posteriorly positioned anus, 24–25 precaudal vertebrae, chin with a barbel, no ventral luminous organ, elongated pelvic fin rays, and a non-protruding snout. Juveniles of P. japonicus (six specimens, 20.4–39.0 mm SL) characteristically have an elongated body, chin with a barbel, ventral lu- minous organ anterior to the anus, elongated pelvic fin rays, a pointed cau- dal fin, 9–10 dorsal fin rays, 66–70 second dorsal fin rays, 68–72 anal fin rays, six pelvic fin rays, 1641–42 vertebrae, and ca. 130 longitudinal scales. Key Words: Teleostei, Gadiformes, Moridae, Antimora microlepis, Physicu- lus japonicus, pelagic juvenile.

Introduction

The family Moridae currently comprises 18 genera and about 110 species, which occur widely from coastal to pelagic waters over the entire world except in the Arctic Ocean (Paulin 1989a; Okamura 1995; Eschmeyer 1998). The adult mor- phology and of the family have been comprehensively studied by Paulin (1983, 1989a) and Cohen (1984). The family is defined by the following four charac- ters: a swim bladder-auditory capsule connection, a caudal skeleton with four or five hypurals and X-Y bones, a joined first neural spine, and distinctive otoliths. Occurrence and morphological information on the early life stages of the family are limited to about 20 species in nine genera (Eretmophorus, , , Halargyreus, , Mora, Physiculus, Rhynchogadus, and Svetovidovia) (Fahay and Markle 1984; Cohen 1986; Okiyama 1988; Markle 1989; Olivar and Fortuño 1991; Ambrose 1996; Meléndez and Markle 1997; Fukui et al. 2003; Comyns