On the colour types in Lycodes nakamurae (Tanaka, 1914) and species composition of the subgenus Furcimanus (Perciformes: Zoarcidae: Lycodes) in the Sea of Japan

Abstract

Two colour types were revealed in a zoarcid fish of the subgenus Furcimanus, genus Lycodes, in the Sea of Japan. A comparison of morphometric, meristic and genetic characters in dark coloured and light coloured individuals suggests that the two colour morphs represent a single species, determined to be Lycodes nakamurae (Tanaka, 1914). Variability in colouration within L. nakamurae and a lack of morphological or molecular characters distinguishing L. nakamurae from L. nishimurai Shinohara & Shirai, 2005 suggest that the latter should be considered a synonym of L. nakamurae (Tanaka, 1914). A record of L. pectoralis in the waters of the Republic of Korea is regarded as a misidentification. Thus, we conclude that only one species of the Lycodes subgenus Furcimanus, L. nakamurae, with dark and light colour morphs as well as specimens of intermediate colouration, inhabits the Sea of Japan.

Quantitative evaluation of color morphotypes in a deep-sea snailfish, <i>Careproctus trachysoma</i> in the Japan Sea and their genetic and environmental backgrounds

“…In the Bothrocara hollandi species complex of deep-sea eelpouts (Kido et al 2020), the frequency of individuals presenting the lighter color morphotype decreases with depth between 600 and 1,100 m, whereas only those of the darker color morphotype are found below 1,100 m (Okiyama 2004). Similar bathymetrical patterns for color morphotype frequency have been reported for deep-sea eelpouts Lycodes yamatoi (Balanov & Solomatov 2008, Balanov & Kukhlevskii 2011 and Lycodes nakamurae (Saveliev et al 2014).…”

“…The former is genetically determined, whereas the latter depends on the environment. Even in the deep sea where transmission of sunlight is limited, some fishes show more than one color morphotype (Okiyama 2004, Balanov & Kukhlevskii 2011, Saveliev et al 2014. However, the formative factors and mechanisms for maintaining this feature have not yet been investigated.…”

Reassessment of multiple species of Gymnelus (Teleostei: Zoarcidae) in Pacific Arctic and boreal regions

“…Lycodes yamatoi Toyoshima 1985 has dark and light color forms with the light morphotype exhibiting individually variable banding (Balanov & Kukhlevskii 2011). Lycodes nakamurae (Tanaka 1914) also has dark and light color forms with variable intermediate morphotypes (Saveliev et al 2014). Bothrocara hollandi (Jordan & Hubbs 1925) has two color forms, a "white" type (pale pinkish) and a "black" type (dark brown or blackish) that are depth-dependent (Okiyama 2004).…”