Morphological differences between species of the sea bass genus Lateolabrax (Teleostei, Perciformes), with particular emphasis on growth-related changes.

Kōji Yokogawa

doi:10.3897/zookeys.859.32624

Abstract

Morphological differences, including growth-related changes, were examined in three morphologically similar East Asian sea bass species, Lateolabraxjaponicus, L.maculatus and L.latus. In many cases, body measurements indicated specific patterns of growth-related proportional changes. Lateolabraxlatus differed from the other two species in having greater body depth, caudal peduncle depth, caudal peduncle anterior depth, snout length, and upper and lower jaw length proportions. In particular, scatter plots for caudal peduncle anterior depth relative to standard length (SL) in that species indicated complete separation from those of the other two species, being a new key character for identification. Comparisons of L.japonicus and L.maculatus revealed considerable proportional differences in many length-measured characters, including fin lengths (first and second dorsal, caudal and pelvic), snout length, post-orbital preopercular width (POPW) and post-orbital length. In particular, snout length (SNL) and POPW proportions of the former were greater and smaller for specimens >200 and ≤ 200 mm SL, respectively. Because the scatter plots of these proportions for the two species did not overlap each other in either size range, identification of the species was possible using a combination of the two characters. In addition, scatter plots of the POPW / SNL proportion (%) of L.japonicus and L.maculatus were almost completely separated throughout the entire size range examined (border level 90%), a further aid to identification. The numbers of pored lateral line scales and scales above the lateral line tended to increase and decrease with growth, respectively, in L.japonicus, whereas scales below the lateral line and gill raker numbers tended to increase with growth in L.maculatus. Because the ranges of these meristic characters may therefore vary with specimen size, they are unsuitable for use as key characters. Accordingly, a new key is proposed for the genus Lateolabrax.

Highlights

The sea basses of the genus Lateolabrax (Lateolabracidae) are common East Asian coastal marine fishes. Bleeker (1854–57) established the genus for a single species, Lateolabrax japonicus (Cuvier, 1828), Katayama (1957) later describing a second species, Lateolabrax latus, from Japan
Similar patterns of growth-related proportional changes common to the three species were observed for some characters, viz., significant positive allometric growth in body width and significant negative allometric growth in head (HL) and pre-dorsal length (PDL), and second dorsal, anal and pelvic fin lengths (SDFL, AFL and P2FL), patterns of the regression curves or plot distributions for the three spe
The present study revealed that most body proportions of the three Lateolabrax species change with growth (Table 3)

Summary

Introduction

The sea basses of the genus Lateolabrax (Lateolabracidae) are common East Asian coastal marine fishes (occasionally occurring in fresh water). Bleeker (1854–57) established the genus for a single species, Lateolabrax japonicus (Cuvier, 1828), Katayama (1957) later describing a second species, Lateolabrax latus, from Japan. Yokogawa and Seki (1995) concluded that differences between the Japanese and Chinese forms of “L. japonicus” were sufficient for the Chinese form to be recognized as a distinct species, being referred to as “spotted sea bass” by Yokogawa and Tajima (1996) It was formally redescribed as Lateolabrax maculatus (McClelland, 1844) in Yokogawa’s (2013b) revision, where Lateolabrax lyiuy (Basilewsky, 1855), which is incorrectly treated as valid and applied to the Chinese form (Kottelat 2013; Eschmeyer 2019), was regarded as a junior synonym of L. maculatus. The range of dorsal fin ray (DFR) counts in L. latus, which had been considered to not overlap that of L. japonicus, had become established as a key identification character (e.g., Katayama 1960a, 1965, 1984; Hatooka 1993). Proportional differences in BD and CPD appear to be based on the premise that their proportions are stable (isometric growth), this has not been verified to date

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