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

Abstract

Morphological differences, including growth-related changes, were examined in three morphologically similar East Asian sea bass species,Lateolabraxjaponicus,L.maculatusandL.latus. In many cases, body measurements indicated specific patterns of growth-related proportional changes.Lateolabraxlatusdiffered 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 ofL.japonicusandL.maculatusrevealed 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 (%) ofL.japonicusandL.maculatuswere 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, inL.japonicus, whereas scales below the lateral line and gill raker numbers tended to increase with growth inL.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 genusLateolabrax.

The First Record of Adult Spotted Sea Bass (Lateolabrax maculatus, McClelland, 1844) from the Coastal Waters of Quang Ninh Province, Vietnam

“…Numerous studies on morphological characteristics have pointed out the differences between species in the genus Lateolabrax. Yokogawa (2019) having a caudal peduncle anterior depth [% of standard length (SL)] ≤ 15% (vs. > 15%), snout length (% of SL) ≤ 9% (vs. > 9%), upper and lower jaw lengths [% of head length (HL) ≤ 45% and 49% (vs. > 45% and 49%, respectively), 14 or fewer dorsal fin rays (vs. 15 or 16, rarely 14), and anal fin ray counts of eight or fewer (vs. 9-11 anal fin rays). Lateolabrax maculatus differs from L. japonicus by the following features: a post-orbital preopercular width (POPW) [% of snout length (SNL)] ≥ 90% (vs. < 90%) [POPW (% of SL) ≥ 7.5% in specimens ≤ 200 mm SL (vs. <7.5%), SNL (% of SL) ≤ 7.7% in specimens >200 mm SL (vs. ≥ 7.7%)], 18 or 19 caudal vertebrae (usually) [rarely 20 (9.2%)] (vs. 20 caudal vertebrae (usually) or 21) [rarely 19 (13.5%)]), 34 or 35 total vertebrae (usually) [rarely 36 (6.6%)] (vs. 36 total vertebrae (usually) or 37 [rarely 35 (13.5%)]), straight first anal pterygiophore (vs. modestly arched first anal pterygiophore in specimens ≥ 90 mm SL), and usually many clear black spots on the lateral and dorsal body regions (usually on or partly below the lateral line) (vs. spots/dots absent on body in specimens > 260 mm SL (although some specimens ≤ 260 mm SL have some dots restricted to the upper part above the lateral line).…”

“…Morphological characters. Dimensions of the fish were taken with digital calipers to the nearest 0.1 mm, and the methods of measurements and counts followed Yokogawa (2019). The following abbreviations were used for the measurable characteristics: AFL, anal fin (longest ray) length; BD, body depth; BWT, body width; CFL, caudal fin length; CFND, caudal fin notch depth; CPAD, caudal peduncle anterior depth; CPD, caudal peduncle depth; CPL, caudal peduncle length; FDFL, first dorsal fin (longest spine) length; HL, head length; IOW, inter-orbital width; LJL, lower jaw length; OD, orbital diameter; PAL, pre-anus length; PDL, pre-dorsal length; POL, post-orbital width; POPW, post-orbital preopercular width; P1FL, pectoral fin length; P2FL, pelvic fin length; SDFL, second dorsal fin (longest ray) length; SL, standard length; SNL, snout length; SOW, sub-orbital width; and UJL, upper jaw length.…”

“…The family Lateolabbracidae, order Perciformes, is comprised of eight species and three genera worldwide, including the genus Lateolabrax, which consists of three species: sea bass (SB), Lateolabrax japonicus (Cuvier, 1828); spotted sea bass (SSB), Lateolabrax maculatus (McClelland, 1844); and blackfin sea bass, Lateolabrax latus (Katayama, 1957) (Bae et al, 2016). The sea basses of the genus Lateolabrax are common East Asian coastal marine fishes (occasionally also occurring in freshwater) (Yokogawa, 2019). Species of the Lateolabrax complex (including L. japonicus and L. maculatus) are morphologically similar, which has led to considerable confusion regarding their taxonomic status.…”

“…In terms of external morphology and anatomical structure, many previous publications have pointed out the different characteristics of species in the Lateolabrax genus, including Chyung (1977), Yokogawa & Seki (1995), Park et al (1996), Kim & Jun (1997), Yokogawa et al (1997), Kang (2000), and Yokogawa (2019). In addition to morphology studies, DNA molecular genetics studies have also been conducted by Park et al (1996), Han et al (2015), and Bae et al (2016), indicating differences among species in the genus Lateolabrax.…”

Body size and age estimation of Chinese sea bass (Lateolabrax maculatus) and evidence of Late Neolithic fishing strategies, a case study from the Guye site

“…FishBase (Froese and Pauly, 2022) and the latest version of Fishes of the World (Nelson et al, 2016) suggest there are only two species in genus Lateolabrax, namely L. japonicus (Japanese sea bass) and L. latus (black fin sea bass). However, local ichthyologists argued that L. maculatus (Chinese sea bass) and L. japonicus are different species based on modern morphology, genetics, ecological habits, and natural distributions (Yokogawa, 1993(Yokogawa, , 2004(Yokogawa, , 2019Yokogawa and Seki, 1995). The Chinese sea bass is characterized by its lifelong black spots on body and dorsal fins although some might gradually downsize with growth, generally they are still larger than the scales (Figure 1).…”