한국산 망둑어과 (Gobiidae) 미끈망둑 (Luciogobius guttatus)의 재검토 및 첫기록종, L. martellii

A re-examination of Gobiid Fish, Luciogobius guttatus, with First Record of L. martellii in Korea

Abstract

우리나라 전 해안을 대상으로 미끈망둑 (Luciogobius guttatus)에 대한 분류학적 재검토를 실시하였다. 그 결과 41개체 (31.3~54.4 mm SL)가 L. martellii로 분류되었다. 본 종의 형태학적 특징은 다음과 같다: 복추골 수 16개; 총 척추골 수 35~37개; 등지느러미 기저부의 길이가 미병부 상부의 길이보다 길거나 같음; 가슴지느러미 상부에 1개의 유리연조; 꼬리지느러미 끝이 하얀색인 특징이 있다. 그중에서 L. guttatus와 형태학적으로 가장 뚜렷한 차이점인 등지느러미 기저부 길이와 미병부 상부의 길이의 차이는 L. martellii의 총모식표본과도 잘 일치하였다. 본 종의 한국명으로 "검정미끈망둑"을 제안한다.

A re-examination of Luciogobius guttatus was conducted using 84 samples, which lives on all coastal waters of Korea. As a result, 41 specimens (31.3~54.4 mm SL) collected from the west and south coasts were classified as L. martellii. The morphological features of L. martellii as follows: number of abdominal vertebrae 16; total number of vertebrae 35~37; dorsal fin base length longer than upper caudal peduncle length or equal; one free ray on its upper pectoral fin; and edge of tail fin white. Among these, the most prominent morphological difference in L. guttatus is comparing the dorsal fin base length and upper caudal peduncle length, which is also well observed in syntypes of L. martellii. We proposed a new Korean name, "Geom-jeong-mi-kken-mang-duk" referring to their color.

INTRODUCTION

The gobiid fishes of genus Luciogobius Gill, 1859, are characterized based on the following morphological features: absence first dorsal fin and pterygiophore; origin of second dorsal fin and anal fin positioned at the rear of the body; elongated body whit scaleless body; depressed head; small eye; more than 31 total vertebrae (Shibukawa et al., 2019).

Recently, Shibukawa et al.(2020) confirmed the validity of the genus Inu, and this made L. ama, L. koma, and L. saikaiensis to be reclassified into the genus Inu.

Consequently, 16 valid species in the genus Luciogobius have been reported to be restricted to Eastern Asia regions such as Korea, Japan, China, Taiwan, Hong Kong, and Russia (Yamada et al., 2009; Ikeda et al., 2019; Dyldin et al., 2020; Koreeda and Motomura, 2022).

Six species of Luciogobius have been reported in Korea; they include L. elongatus, L. grandis, L. guttatus, L. pallidus, L. parvulus, and L. platycephalus (Kim, 2012; Cho and Choi, 2014; Kim et al., 2021). Among them, L. guttatus as a single species has been questioned due to morphological and ecological considerations.

Therefore, we compared the specimens collected from all coast of Korea, including Baekryeong Island in the northwestern part of Korea and Jeju Island, with the syntypes of L. martellii, which had been misclassified as L. guttatus owing to their morphological resemblance. As a result, we identified the presence of L. martellii in the samples collected in Korea, so we described L. martellii for the first time in Korea.

MATERIALS AND METHODS

All specimens are fixed in 10% formalin thereafter preserved in 70% ethanol. Methods of counting and measurements followed Hubbs and Lagler (2004) and are expressed in percentage of standard length (SL) or head length (HL). Measurements were made to the nearest 0.1 mm using digital vernier calipers. Vertebrae were determined from radiographs (X-eye 5000NSL, SEC, Korea) and count method followed Akihito in Masuda et al.(1984) (NNIBR-P42096~42098(3), 44977~44978(2), 44992, 45005~45007(3), 45046, 45054, 45099, 45111, 45113, 45151~45154(4)). The vouchers are deposited at the Nakdonggang National Institute of Biological Resources, Korea.

TAXONOMIC ACCOUNTS

Luciogobius martellii Di Caporiacco, 1948

(New Korean name: Geom-jeong-mi-kken-mang-duk)

(Figs. 2, 3; Table 1)

Table 1. Comparison of counts and proportional measurements of Luciogobius martellii and L. guttatus

Luciogobius martellii Di Caporiacco, 1948: 200 (type locality: Hong Kong); Okiyama, 2001: 141; Shibukawa et al., 2019: 29 (Shizuoka, Japan).

Luciogobius sp. Arai, 1981: 161 (Izu Peninsula, Japan).

Luciogobius sp. 6 Akihito et al., 2013: 1378 (Japan).

Luciogobius sp. Matsui et al., 2014: 4 (Wakasa Bay, Japan).

Material examined. Total 41 specimens (Fig. 1): 10 specimens (SOKN-P1039~P1048), 45.0~51.5 mm SL , Eurwang-dong, Jung-gu, Incheon, Korea, 23 June 2020; 8 specimens (SOKN-P1050~P1057), 46.2~54.4 mm SL, Uihang-ri, Sowon-myeon, Taean-gun, Chungcheongnam-do, Korea, 18 June 2020; 1 specimen (SOKN-P1059), 53.7 mm SL, Seondo-ri, Biin-myeon, Seocheon-gun, Chungcheongnam-do, Korea, 1 July 2020; 8 specimens (SOKN-P1060, P1062~P1068), 37.9~48.7 mm SL, Dodun-ri, Seo-myeon, Seocheon-gun, Chungcheongnam-do, Korea, 2 July 2020; 2 specimens (SOKN-P1179, P11 81), 41.0~44.1 mm SL, Mangchi-ri, Irun-myeon, Geoje-si, Gyeongsangnam-do, Korea, 21 May 2020; 6 specimens (SOKN-P1182~P1186, P1188), 40.6~53.7 mm SL, Seungeon-ri, Anmyeon-eup, Taean-gun, Chungcheongnam-do, Korea, 21 June 2020; 1 specimen (SOKN-P1210), 31.3 mm SL, Nampo-ri, Baengnyeong-myeon, Ongjin-gun, Incheon, Korea, 31 March 2021; 1 specimen (NNIBR-P45099), 48.8 mm SL, Uihang-ri, Sowon-myeon, Taean-gun, Chungcheongnam-do, Korea, 18 June 2020; 2 specimens (NNIBR-P45005, P45007), 40.1~43.8 mm SL, Uihang-ri, Sowon-myeon, Taean-gun, Chungcheongnam-do, Korea, 18 June 2020; 2 specimens (NNIBR-P45111, P45113), 44.5~48.7 mm SL, Seungeon-ri, Anmyeon-eup, Taean-gun, Chungcheongnam-do, Korea, 21 June 2020, collected by Seung-Ho Choi and Min-Soo Kim, hand net at gravel beaches.

Fig. 1. Sampling sites of Luciogobius martellii from Korea.

Description. Meristic and measurements are shown in Table 1. Dorsal fin rays 11~14; anal fin rays 12~15; pectoral fin rays 15~18; free ray on upper pectoral fin 1; abdominal vertebrae 16; total number of vertebrae 36~37.

Body elongated, lacking scales, consistent depth throughout and slight compression towards the posterior end. Head depressed. Mouth terminal and maxilla extending beyond the posterior border of eye. Lower jaw above the upper jaw. Small conical teeth on both jaws. Pectoral fin rounded shape. Pelvic fin united, forming a sucker. First dorsal fin absent. Anal fin originates anterior to the dorsal fin. Length of dorsal fin base is longer than length of upper caudal peduncle length or equal. Margin of caudal fin circular.

Coloration when fresh. The head and body background white, with black blotches covered very densely. Ventral area white, with few spots present from the chin to the origin of anal fin. Black spots concentrate at the base of all fins and gradually diminish towards the edges, giving the appearance of relative transparency. Edge of caudal fin translucent white.

Coloration after preserved specimen. Body predominantly dark brown. Dorsum darker than ventral surface. White edge of the caudal fin consistently preserved.

Ecological notes. This species inhabits rocky intertidal zones and gravel beaches. Places unaffected by freshwater or very little, even though they are affected.

Distribution. Hong Kong (The original description is Hong Kong, but in tags of syntypes, it was noted as Shanghai) (Nocita and Vanni, 1997), Japan (Shibukawa et al., 2019) and Korea.

Remarks. In Japan, taxonomic discussions on L. guttatus and several related studies have consistently suggested the existence of more than two species within the L. guttatus group, with very broad habitat range (Arai, 1981; Mukai and Nishida, 2004; Yamada et al., 2009; Hashimoto et al., 2014; Matsui et al., 2014; Shibukawa et al., 2019).

Arai (1981) distinguished two types of L. guttatus, the ocean type and the freshwater type, based on the differences in the number of abdominal vertebrates in the specimens from Izu Peninsula in Japan. Mukai and Nishida (2004) and Hashimoto et al. (2014) supported the report of Arai (1981) because mtDNA genetic analysis revealed the there are some lineage groups whose habitats are separated into intertidal zones and estuaries.

These studies seems nuclear and confusing due to the limited research on L. martellii, a species which resembes L. guttatus. Shibukawa et al. (2019) addressed this issue by directly examining the syntypes of L. martellii and presented the morphological features of L. martellii as follows: dorsal fin base length longer than upper caudal peduncle length or equal; abdominal vertebrae 16; total number of vertebrae 35~37; and edge of tail fin white. Furthermore, we reaffirmed the classification method of Shibukawa et al. (2019) by measuring the syntypes of L. martellii from Natural History Museum, “La Specola” Section, Florence University.

In this study, the samples collected from the west and south coasts reflected the aforementioned Japanese research results, showing apparent differences in morphological characteristics and habitats; hence, we identified these specimens as L. martellii.

Additionally, L. martellii, has a free ray on its upper pectoral fin, a feature shared by L. guttatus. However, L. martellii can be distinguished from the five Luciogobius species recorded in Korea, excluding L. guttatus, as follows: L. elongatus (1 vs. 0), L. grandis (1 vs. 3~4), L. pallidus (1 vs. 0), L. parvulus (1 vs. 0), and L. platycephalus (1 vs. 3~4) (Arai, 1970; Kim, 2012; Cho and Choi, 2014; Kim et al., 2021).

Therefore, in this study, L. martellii is listed as an unrecorded species in Korea, and we proposed a new Korean name, “Geom-jeong-mi-kken-mang-duk” referring to their color.

Comparative materials. L. martellii: Total 2 specimens: MZUF-5556~5557, 40.0~42.2 mm SL, syntypes of L. martellii, Hong Kong.

Fig. 2. Syntypes of Luciogobius martellii(MZUF-5556, 42.2 mm SL; MZUF-5557, 40.0 mm SL). Photo by Annamaria Nocita.

Fig. 3. Luciogobius martellii, NNIBR-P45005, 43.8 mm SL, from the Irun-myeon, Geoje-si, Gyeongsangnam-do, Korea.

L. guttatus: Total 43 specimens: 6 specimens (SOKN-P1012, P1014~P1018), 48.3~64.3 mm SL, Sadong-ri, Jindong-myeon, Masanhappo-gu, Changwon-si, Gyeongsangnam-do, Korea, 19 May 2020; 3 specimens (SOKN-P1019~1021), 59.2~63.0 mm SL, Mulchi-ri, Ganghyeonmyeon, Yangyang-gun, Gangwon-do, Korea, 28 April 2020; 1 specimen (SOKN-P1022), 52.9 mm SL, Eosin-ri, Hoehwa-myeon, Goseong-gun, Gyeongsangnamdo, Korea, 19 May 2020; 1 specimen (SOKN-P1023), 56.1 mm SL, Yojang-ri, Jindong-myeon, Masanhappo-gu, Changwon-si, Gyeongsangnam-do, Korea, 19 May 2020; 1 specimen (SOKN-P1049), 49.4 mm SL, Uihang-ri, Sowon-myeon, Taean-gun, Chungcheongnam-do, Korea, 18 June 2020; 2 specimens(SOKN-P1061, P1069), 40.2~44.7 mm SL, Dodun-ri, Seo-myeon, Seocheon-gun, Chungcheongnam-do, Korea, 2 July 2020; 3 specimens (SOKN-P1070, P1072~P1073), 62.7~70.0 mm SL, Gwanpo-ri, Jangmok-myeon, Geoje-si, Gyeongsangnam-do, Korea, 24 May 2020; 4 specimens (SOKN-P1172~P1175), 61.5~73.1 mm SL, Jangjwa-ri, Donghae-myeon, Goseong-gun, Gyeongsangnam-do, Korea, 20 May 2020; 1 specimen (SOKN-P1176), 56.3 mm SL, Sinwol-ri, Goseong-eup, Goseong-gun, Gyeongsangnam-do, Korea, 19 May 2020; 4 specimens (SOKN-P1194~P1197), 56.4~59.1 mm SL, Haye-dong, Seogwipo-si, Jeju-do, Korea, 9 September 2020; 4 specimens (SOKN-P1205~P1206, P1208~P1209), 49.5~52.4 mm SL, Nampo-ri, Baengnyeong-myeon, Ongjin-gun, Incheon, Korea, 31 March 2021; 1 specimen (SOKN-P1212), 65.3 mm SL, Jeongdo-ri , Wando-eup, Wando-gun, Jeollanam-do, Korea, 5 June 2020; 2 specimens (NNIBR-P44977~P44978), 60.2~63.7 mm SL, Sadong-ri, Jindong-myeon, Masanhappo-gu, Changwon-si, Gyeongsangnam-do, Korea, 19 May 2020; 1 specimen (NNIBR-P45046) 67.7 mm SL, Gwanpo-ri, Jangmok-myeon, Geoje-si, Gyeongsangnam-do, Korea, 24 May 2020; 1 specimen (NNIBR-P44992), 64.7 mm SL, Jangjwa-ri, Donghae-myeon, Goseong-gun, Gyeongsangnam-do, Korea, 20 May 2020; 4 specimens(NNIBR-P45151~P45154), 53.3~71.5 mm SL, Haye-dong, Seogwipo-si, Jeju-do, Korea, 9 September 2020; 3 specimens(NNIBR-P42096~P42098), 50.8~51.3 mm SL, Nampo-ri, Baengnyeong-myeon, Ongjin-gun, Incheon, Korea, 31 March 2021; 1 specimen (NNIBR-P45054), 62.6 mm SL, Jeongdo-ri , Wando-eup, Wando-gun, Jeollanam-do, Korea, 5 June 2020, collected by Seung-Ho Choi and Min-Soo Kim, hand net at gravel beaches.