In the present paper is given a review of fishes of the family Chlorophthalmidae found in the deep waters of Japan. The specimens referable to two genera and four species with the annexed addition of two subspecies, of which one species and two subspecies seem to be new to science, are chiefly secured from the Mimase Market (Kochi City), Kôchi Prefecture and the Chôshi Market, Chiba Prefecture. All are secured by a kind of the small fishing motor-boat known as “kisen-teguri”, operated at grounds some 100 meters deep. In the following descriptions the body length is measured from the anterior end of upper jaw to the upper insertion of caudal; the length of head from the anterior end of upper jaw to the posterior end of opercle; the number of caudal rays is counted excluding unbranched ones; the color notes all are based on the material preserved in for malin. All the specimens except two of Chlorophthalmus albatrossis borealis from Chô-shi, which are collections of the Department of Fisheries, Kyôto University, are deposited in the Biological Laboratory, Liberal Arts Faculty, Kôchi University, Kôchi City, Japan. Before proceeding further, I wish to express my hearty thanks to Dr. Shigeho Tanaka, ex-professor of the Tokyo University, who offered kind advice in various ways.
This report is based on a physiological study of the digestive function in the mouth of Ophiocephalus argus CANTOR. The resuls obtained are summarized as follows: 1. Besides the usual teeth known in other fishes, this fish has teeth on the parasphenoid. 2. The young, up to ca. 62 mm in total length, have few teeth on the gillarches. 3. This fish is polyphobont and grows to a size of ca. 510 mm in total length within 16 months. The total number of teeth at thi3 size is ca. 4, 000. 4. It is presumed that the stage in which the voracity of this fish appears remarkably and attacks other animals is more than 16 months after hatching. 5. It is presumed that the suitable term for artificial culture of this fish in ponds is about 6 months, and that the body-weight suitable for harvest is about 1.2-0.23kg.
The new species here described under the name of Carapus owasianus is based on a specimen (MATSUBARA'S Fish Coll. No.18871) obtained by a deep-sea trawler on November 17, 1952 from off Owasi, Mie Prefecture, at a depth of about 100 hiro (about 151.5 meters). The present study is a part of the results of our investigations on the deep-water fishes of Japan and its adjacent regions. The expenses for the studies of the present series were defrayed from 1943 to 1945 from a research fund contributed by Viscount Keizo SHIBUSAWA and since 1948 from the grant-in-aid by the Ministry of Education.
In December of 1951 the writers published a description of a previously unknown species of the morid genus Physiculus, P. jordani (BOHLKE and MEAD, 1951: 27). The description was based on a single specimen trawled by the U. S. Fish Commission Steamer “Albatross” off Suruga Bay, Japan. In March of the following year Dr. Toshiji KAMOHARA of Kochi University described P. inbarbatum as new (KAMOHARA, 1952: 94), designating as types three specimens obtained from the Mimase market (Kochi City, Shikoku). Since these two nominal species appeared to be strikingly similar in many respects, a direct comparison of the type material seemed desirable. This comparison was effected through the kind cooperation of Dr. KAMOHARA, who made available to us not only his types but also several specimens subsequently collected from the type locality. Specimens of P. jordani and P. inbarbatum are similar in the absence of the mandibular barbel, in the extremely slender caudal peduncle, in color pattern and in many other general features. In several meristic and morphometric characters, however, the type of P. jordani differs significantly from those of P. inbarbatum. Counts and proportional measurements of the specimens at hand are recorded in Table 1. It is immediately apparent that our specimen has a greater number of dorsal and anal rays, a slightly longer and broader head, a longer snout, a wider interorbital space and more posteriorly placed pectoral and ventral fins than has Dr. KAMOHARA'S material. We cannot, therefore, assign P. inbarbatum a place in the synonymy of P. jordani, although it seems improbable that two closely related and morphologically similar populations could have evolved and maintained their identity while living together in waters off Shikoku and southern Honshu. A third form apparently closely related to these two is Physiculus edelmanni (BRAUER, 1906: 274, pl. 12: 6, from the Indian Ocean off the coast of Africa. Counts and measurements of this species, taken from BRAUER'S type description, are also included in the table. In many respects the specimens of P. inbarbatum appear to be intermediate between P. jordani, as originally understood, and P. edelmanni. A biometric study of the members of this complex based on material from various localities and depths may demonstrate the existence of but a single widespread and highly variable species. However, since available representatives of the three forms are in several respects at variance with one another the three nominal species must tentatively be considered distinct.