Background
Fishes of the genus Hypoptychus Steindachner 1880 (family Hypoptychidae) occurs in cold areas of the North Pacific near Korea, Japan, and Russia (Froese and Pauly 2017). The single species of this genus, Hypoptychus dybowskii Steindachner 1880, has been recognized in those regions (Kim et al. 2005a; Senou 2013; Parin et al. 2014). In Korea, Mori and Uchida (1934) were the first to report H. dybowskii from the coast of Hamgyeongnam-do, North Korea, but no morphological description was provided. Subsequently, Chyung (1977) described the species morphology and distribution and defined the Korean common name as “Yang-mi-ri”. Subsequently, many Korean ichthyologists regarded the distribution of this species in Korea as on the coast of the East Sea (Kim et al. 2005a; Kim et al. 2005b). However, no additional confirmed record of this species has been reported south of Hamgyeongnam-do, except that of Lee et al. (1997), for which confirmation is required. Another issue is the incorrect identification of this species. Chyung (1977) named Ammodytes personatus Girard 1856 (revised to Ammodytes japonicus Duncker and Mohr 1939 for Korean specimens by Kim et al. 2017), which is similar to H. dybowskii in external shape. In Korean, A. japonicus is called “Kka-na-ri”; however, Korean people who are not ichthyologists called this species “Yang-mi-ri” rather than “Kka-na-ri”. Subsequently, some researchers have used the incorrect scientific name or the Korean common name (Kim et al. 2008a; Lee et al. 2011; Kim et al. 2012). Providing wrong information can cause serious problems in communication and scholarship, so a correction is required.
Therefore, the present study provides a morphological description of H. dybowskii on the basis of new material from Korea and compares this species with A. japonicus (= A. personatus for Korean specimens) in terms of external morphology.
Methods
Two specimens of H. dybowskii were collected from Goseong-gun, Gangwon-do, Korean coast of the East Sea, with a hand net in May 2017. They were fixed as whole-body specimens in 99% ethanol. Counts and measurements follow Hubbs and Lagler (2004) using digital vernier calipers (to the nearest 0.1 mm). The fin rays were counted under a stereomicroscope (SZX16, Olympus, Japan). The specimens have been deposited at the National Marine Biodiversity Institute of Korea, Marine Fish Diversity (MFD).
Results
(Korean name: Yang-mi-ri) (Figs. 1 and 2a)
Hypoptychus dybowskii Steindachner 1880: 158 (type locality: Peter the Great Bay); Mori and Uchida 1934: 31; Lindberg and Krasyukova 1975: 201; Kim et al. 2005a: 199; Senou 2013: 609; Parin et al. 2014: 203.
Hypoptychus steindachneri Franz 1910: 8 (type locality: Fukuura, Japan).
MFD-1052–1053, two specimens, Machajin beach, Machajin-ri, Hyeonnae-myeon, Goseong-gun, Gangwon-do, Korea, hand net, 31 May 2017.
Counts are provided in Table 1. Proportions as a percentage of standard length: head length 22.3–22.6; predorsal length 63.3–64.8; preanal length 65.4–66.8; body depth 7.3–8.4; caudal peduncle depth 2.8–3.0; caudal peduncle length 7.9–9.1; postorbital length 8.7–9.4; pectoral fin length 13.7–13.9. Proportions as a percentage of head length: eye diameter 26.4; snout length 34.0–35.2; interorbital width 24.5–25.8; suborbital width 10.1–10.7; upper jaw length 32.7–34.6. Body elongate, compressed. Head small and eyes large. Snout somewhat long and pointed. Mouth moderate and terminal. Anterior tip of lower jaw projects beyond anterior tip of upper jaw. Posterior tip of the maxilla does not reach anterior margin of eye. Small conical teeth on upper jaw. Interorbital region slightly wide and flat. Head and body naked. A single lateral line extending to caudal-fin base in a straight line. Dorsal fin located opposite to anal fin on posterior part of body; origin of dorsal fins just above that of anal fin. Dorsal and anal fins high anteriorly and gradually decreasing in height posteriorly. Pectoral fins slightly large. Caudal fin forked. Pelvic fin absent. Longitudinal dermal fin fold developed on ventral surface of body; its posterior tip in male hook-like.
|
Hypoptychus dybowskii |
Ammodytes personatus |
||
|---|---|---|---|
|
Present study |
Senou (2013) |
Kim et al. (2008b) |
|
|
Number of specimens |
2 |
– |
90 |
|
Standard length (mm) |
70.5–71.3 |
– |
91.0–228.1 |
|
Counts |
|||
|
Dorsal fin rays |
21 |
19–21 |
53–60 |
|
Anal fin rays |
21–22 |
19–22 |
27–33 (n = 89) |
|
Pectoral fin rays |
9 |
9–10 |
13–16 |
When fresh, head and body reddish-yellow and semi-transparent with small black dots (Figs. 1 and 2a). Black dots well developed on anterior region of lower jaw and ventral region of gill membrane. All fins semi-transparent. Membranes of dorsal and anal fins with small black melanophores. After alcohol fixation, head and body pale and whitish.
Discussion and conclusion
The present study provides a morphological description of H. dybowskii on the basis of specimens collected from the coast of the East Sea, Goseong-gun, Gangwon-do, south of Hamgyeongnam-do. The present specimens can be identified as H. dybowskii in the family Hypoptychidae based on the following characters: absence of scales and pelvic fin; dorsal and anal fins without spines and located in the posterior region of the body; and elongate body (Nelson et al. 2016). The present specimens well agree with the original description of H. dybowskii in terms of body shape and the locations of the dorsal and anal fins (Steindachner 1880). Many people often confuse H. dybowskii and A. japonicus because the Korean common name or dialect “Yang-mi-ri” is applied to both species. Although they have a similar body shape, these two species possess different external morphologies. Hypoptychus dybowskii can be distinguished from A. japonicus by means of the location of the origin of the dorsal fin (behind to above anus in H. dybowskii vs. above the pectoral fin in A. japonicus) (Fig. 2), and the number of dorsal and anal fin rays (19–21 and 19–22, respectively, vs. 53–60 and 27–33, respectively) (Table 1) (Kim et al. 2005a; Kim et al. 2008b; Senou 2013). Furthermore, H. dybowskii is not exploited as a fisheries resource, but A. japonicus, which can easily be found in local fish markets in Korea, is commonly consumed in Gangwan-do. Therefore, the samples used in several studies (Kim et al. 2008a; Lee et al. 2011; Kim et al. 2012), which were collected from fish markets, are more likely to be A. japonicus than H. dybowskii.
