Larval identification following metamorphosis in the slender brown moray Strophidon ui from the western North Pacific

Abstract

Leptocephalus larvae collected from the western North Pacific, and characterized by yellow head pigmentation and many myomeres, were identified as the slender brown moray Strophidon ui following observations of metamorphosis in an aquarium. The leptocephali had 184-196 total myomeres (84-90 predorsal, 116-122 preanal) and 95-102 last vertical blood vessel myomeres. A horizontally elongate group of irregular melanophores before and behind the eye formed a poorly defined band. Some irregular melanophores on the iris encircled the pupil, and minute melanophores occurred ventrally on the spinal cord and along the dorsal and anal fin bases. Yellow pigments were present in anterior and posterior regions adjacent to the eye in fresh specimens. It was possible to clearly distinguish the leptocephali of S. ui from six unassigned leptocephalus types and Gymnothorax minor reported previously from the same region, owing to the lower total myomere counts (106-142) in the latter. This is the second description of specifically identified muraenid leptocephali from the western North Pacific.

The phylogenetic significance of colour patterns in marine teleost larvae

“…Tawa et al . (2012: fig. 2) published a colour image of a muraenid leptocephalus ( Strophidon ui ) that exhibits xanthophores in front of and behind the eye, and Miller (2009) provided images (Fig.…”

“…2AnguilliformesMuraenidae Strophidion ui YTawa et al . (2012)AnguilliformesMuraenidaeUnknownUnknownYFig. 5 and Miller (2009)AnguilliformesNettastomatidae Saurenchelys sp.YFig.…”

A review of the genus Strophidon (Anguilliformes: Muraenidae), with description of a new species

“…Strophidon ui was regarded as a junior synonym of S. sathete by Böhlke (1995) and the status was followed by most subsequent studies. Later, Hatooka (2002) considered S. ui a valid species and his opinion is followed by several authors ( e.g ., Hibino et al ., 2017; Koeda, 2018; Tawa et al ., 2012). The lack of clearly and concordantly defined diagnosis of S. ui has led to widespread taxonomic confusion, especially between S. ui and the most morphologically similar species S. sathete .…”

“…However, Gymnothorax dorsalis was recently placed in Strophidon by Loh et al . (2015b) due to the close genetic relationship and a combination of morphological characteristics, and S. ui has been treated as a valid species in several recent studies, although none of them provided the diagnostic character to distinguish it from their congeners (Hatooka, 2013; Hibino et al ., 2017; Koeda, 2018; Tawa et al ., 2012). Recently, Strophidon dawydoffi was described by Prokofiev (2020) based on a 650 mm specimen from Nha Trang, Vietnam, characterized by an exclusively long tail, much‐elongated body, fewer preanal vertebrae and the uniquely variegated colour of the body and oral cavity.…”

“…However, Gymnothorax dorsalis was recently placed in Strophidon by Loh et al (2015b) due to the close genetic relationship and a combination of morphological characteristics, and S. ui has been treated as a valid species in several recent studies, although none of them provided the diagnostic character to distinguish it from their congeners (Hatooka, 2013;Hibino et al, 2017;Koeda, 2018;Tawa et al, 2012).…”