First Record of a Gaper Champsodon longipinnis (Perciformes: Champsodontidae) from Korea

Abstract

This is the first report of Champsodon longipinnis (Champsodontidae) collected from Korea. The specimen (100.9 mm in standard length) was caught by a bottom trawl in the coastal waters off Busan, Korea. This species is characterized by the following morphological traits: body with small denticulate scales except abdomen around pelvic fin base; posterior end of maxilla extending beyond margin of eye; dark pigmentation on most of the first dorsal fin, upper half of the first to the fourth soft ray of the second dorsal fin, and partial upper lobe of caudal fin. We add C. longipinnis to the Korean fish fauna and suggest a new Korean name, "Jeom-ak-eo-chi," for the species.

Introduction

The champsodontid fishes are recognized by a sole genus, Champsodon Günther, 1867, containing 13 species and are distributed in the tropical and Indo-Pacific Ocean (Nelson, 2006). The family is characterized by having a large head and mouth, an elongate compressed body densely covered with small denticulate scales, a short spinous dorsal fin, small pectoral fins, unusually large pelvic fins, and a forked caudal fin (Nemeth, 1994). Among the 13 species of the genus Champsodon, only one species (Champsodon snyderi Franz, 1910) has been reported in Korea so far (Kim et al., 1995). A single specimen of Champsodon longipinnis was collected by a bottom trawl in the coastal waters off Busan on October 28, 2012. Here, we describe the morphological characteristics of C. longipinnis as an addition to the list of Korean fishes based on the specimen.

 

Materials and Methods

Counts and measurements followed the method of Hubbs and Lagler (2004). The examined specimen was deposited at the Fish Genetics and Breeding Laboratory, Jeju National University (JNU), Korea.

 

Results and Discussion

Champsodon longipinnis Matsubara and Amaoka, 1964

(New Korean name: Jeom-ak-eo-chi)

(Figs. 1, 2; Table 1)

Fig. 1.Champsodon longipinnis, JNU-869, 100.9 mm SL, bottom trawl, off Busan, Korea. Scale bars = 10 mm.

Table 1.Comparison of morphological characters of Champsodon longipinnis

Matsubara and Amaoka in Matsubara, Ochiai, Amaoka and Nakamura, 1964: 10 (type locality: off Todoro, Miyazaki Prefecture, Japan); Amaoka, 1984: 221 (Japan); Nemeth, 1994: 357 (Australia, Indonesia, Philippines, Japan); Mooi and Johnson, 1997: 158 (Australia, Philippines, Japan); Nemeth, 2001: 3499 (Australia, Indonesia, Philippines, Japan); Hatooka, 2002: 1071 (Japan).

Material examined

JNU-869, one specimen, 100.9 mm in standard length (SL), bottom trawl, ~100 m depth, off Busan, Korea, 28 October 2012.

Description

Counts and measurements for the present specimen are shown in Table 1.

Body compressed and covered with small denticulate scales except abdomen around pelvic fin base (Fig. 2A); head and mouth large; posterior end of maxilla extending beyond margin of eye; eye with dark posterodorsal cirrus split into two branches; five pairs of sensory papillae between parallel bony ridges on dorsal surface of head, from snout to interorbital; transverse row of ten sensory papillae between the posterior margins of the pterotic ridges (Fig. 2B); pectoral fins short, reaching level of the fifth dorsal-fin spine; pelvic fins elongate, reaching level of anus; upper half of the first dorsal fin, half of the first-fourth soft ray of the second dorsal fin and partial upper lobe of caudal fin dark.

Fig. 2.The Illustrations of the head region of Champsodon longipinnis. A, dorsal sensory papillae and bony ridges on the head (P1, five pairs of sensory papillae between parallel bony ridges on the dorsal surface of the head; P2, transverse row of ten sensory papillae between the posterior margins of the pterotic ridges); B, distribution pattern of ventral scales shaded grey; pelvic fins are cut to expose the abdomen. Scale bar = 5.0 mm.

Color when fresh: Body dark brown dorsally; silvery white ventrally; with a row of spots where dark and light pigmentation meet; a part of the first dorsal fin, second dorsal and partial upper lobe of caudal fin dark; caudal base with dark blotch.

Color in alcohol: Dark brown dorsally color paler than alive; a part of the first dorsal fin, the second dorsal and partial upper lobe of caudal fin still dark.

Distribution

Widely known from Indo-West Pacific: Japan, Philippines, Indonesia, Australia (Matsubara and Amaoka in Matsubara et al., 1964; Nemeth, 1994; Hatooka, 2002), and Korea (coastal waters off Busan, present study).

Remarks

The present specimen was easily distinguishable from the family (Champsodontidae) by having small denticulate scales except abdomen around pelvic fin base (Fig. 2A), posterior end of maxilla extending beyond margin of eye, dark pigmentation on most of the first dorsal fin, upper half of the first-fourth soft ray of the second dorsal fin, and upper lobe of caudal fin. The morphological characteristics of the specimen were well matched with the species description given by previous studies (Amaoka, 1984; Nemeth, 1994), and all counts of the present specimen coincide with those of Nemeth (1994), C. longipinnis is morphologically similar to C. pantolepis (Nemeth, 1994), but is distinguished from the latter by having a pectoral fin with 14-16 rays (vs. 13 rays for C. pantolepis), posterior end of maxilla extending beyond margin of eye (vs. almost reaching posterior margin of eye) (Fig. 1) (Nemeth, 1994; Hatooka, 2002). It is also morphologically similar to C. snyderi which is only known Korean Champsodontid fish at a glance. However, C. longipinnis is easily distinguished from C. snyderi by having dark pigmentation on dorsal fin and caudal fin. We propose a new Korean name, “Jeom-ak-eo-chi,” for C. longipinnis.