Research Article |
Corresponding author: Kōji Yokogawa ( gargariscus@ybb.ne.jp ) Academic editor: Nina Bogutskaya
© 2019 Kōji Yokogawa.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Yokogawa K (2019) Morphological differences between species of the sea bass genus Lateolabrax (Teleostei, Perciformes), with particular emphasis on growth-related changes. ZooKeys 859: 69-115. https://doi.org/10.3897/zookeys.859.32624
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Morphological differences, including growth-related changes, were examined in three morphologically similar East Asian sea bass species, Lateolabrax japonicus, L. maculatus and L. latus. In many cases, body measurements indicated specific patterns of growth-related proportional changes. Lateolabrax latus 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.
Lateolabrax japonicus, Lateolabrax maculatus, Lateolabrax latus, morphology, growth, new key
The sea basses of the genus Lateolabrax (Lateolabracidae) are common East Asian coastal marine fishes (occasionally also occurring in fresh water).
General aspects of small (fingerling) and large (adult) individuals of Lateolabrax japonicus (A, B), L. maculatus (C, D) and L. latus (E, F) in fresh condition. A KPM-NI 27449 (91.9 mm SL) B KPM-NI 30671 (331.0 mm SL) C uncatalogued specimen (94.3 mm SL) D BSKU 100776 (265.0 mm SL) E KPM-NI 29044 (97.1 mm SL) F KPM-NI 24656 (369.0 mm SL). A, B, E and F were photographed by Hiroshi Senou (KPM), C and D were photographed by K. Yokogawa.
Lateolabrax latus has been distinguished from L. japonicus by having greater proportions of body and caudal peduncle depth (BD and CPD), more dorsal and anal fin rays (≥15 and ≥9, respectively), fewer scales below the lateral line (≤16) and possessing ventromandibular scale rows (VSRs) (
Lateolabrax maculatus has been characterized by many clear black spots on the body, but this character is also problematic as a few individuals of the species lack such spots (
Thus, morphological identifications of the three Lateolabrax species remain problematic, although genetic studies have shown them to be independent species (
Measurements were based on the following Lateolabrax specimens, which have been deposited in the Laboratory of Marine Biology, Faculty of Science, Kochi University (BSKU), Kanagawa Prefectural Museum of Natural History (KPM), the Kagoshima University Museum (KAUM) and Tokushima Prefectural Museum (TKPM), together with some uncatalogued ones. Because presence of some specialized sea bass populations, which resulted from introgressive hybridization between Lateolabrax japonicus and L. maculatus, have been reported from Japan (Ariake and Yatsushiro Seas) (
Lateolabrax japonicus (229 specimens). BSKU 100789–100804 (16), 100826, KPM-NI 9697, 9698, KAUM–I. 82683–82703 (21), 93431–93439 (9), uncatalogued specimens (54) – all Kagawa Pref.; BSKU 101505–101541 (37), Hyogo Pref., Seto Inland Sea; BSKU 100739–100769 (31), 100788, Yamaguchi Pref., Seto Inland Sea; BSKU 66400, KPM-NI 9699 – both Uwajima, Ehime Pref., TKPM-P 352 (20), Tokushima Pref.; KPM-NI 27449, Mie Pref.; KPM-NI 30671, Sagami Bay; BSKU 100837, 100839, 100842, 100845, 100846, 100852, 100854, 100855, 100859–100862 (4), 100865, 100867, 100873, 100874, 100876, 100878, 100879, 100882, 100883, 100886, 100888, 100891, 100893, 100897, 100898, 100900–100902 (3), 100904, 100906, 100907 – all Ishikawa Pref.
Lateolabrax maculatus (170 specimens). BSKU 100770–100787 (18), 101787–101826 (40), a wild strain imported from Yantai, China and cultured in Kagawa, Japan; TKPM-P 1655 (40), uncatalogued specimens (33), a wild strain imported from China (locality unknown) as aquacultural seeds; BSKU 66398, 66399, 66401–66406 (6), TKPM-P 6114, 6140, KPM-NI 9686–9689 (4), 9691–9694 (4), uncatalogued specimens (17) – all Uwajima, Ehime Pref. (presumed escapees from nurseries); TKPM-P 16897, KPM-NI 9696, uncatalogued specimens (2) – all eastern Seto Inland Sea (presumed escapees from nurseries).
Lateolabrax latus (136 specimens). BSKU 101827, Awaji I., Seto Inland Sea; BSKU 100553, 100554, 100556–100561 (6), 101835, TKPM-P 372 – all Tokushima Pref.; KAUM–I. 1895 (4) locality unknown; KAUM–I. 25203, 29117, KPM-NI 24246–24248 (3), 24252–24256 (5), 24648–24656 (9), 24935–24940 (6) – all Yakushima I.; KAUM–I. 33778, Ikarajima I., Yatsushiro Sea.; KAUM–I. 39049–39051 (3), 39055–39058 (4), 39128, 39129, 61956, 64737, 64738, 66393, 66394, 67090, Tanegashima I.; KAUM–I. 42043, 42044, 51058–51068 (11), 54112, 54668, 57963, 58161, 58162, 61406, 61407, 61577, 63162–63169 (8), 63625, 65483–65485 (3), 65671, 80441–80444 (4), Kagoshima Pref. (mainland); KAUM–I. 66081, 75375, 75660, 75815, 75816, Nagasaki Pref.; KPM-NI 21869, 22433, 23429, Shizuoka Pref.; KPM-NI 24566, 24579, 24615, 35333, Miyazaki Pref.; KPM-NI 26185, 26186, 26992, 28599 (3), 29040, Chiba Pref.; KPM-NI 26973, 26975–26979 (5), 26988–26991 (4), Uwajima, Ehime Pref.; KPM-NI 29041–29048 (8), 31568, Kochi Pref.; KPM-NI 29279, 37509, 37919, 37920, Kanagawa Pref.
Methods of measurements and counts followed
Abbreviation | Abbreviation | ||
Length-measured body characters | Post-orbital preopercular width | POPW | |
Standard length | SL | Upper jaw length | UJL |
Pre-anus length | PAL | Lower jaw length | LJL |
Body depth | BD | Meristic characters | |
Body width | BWT | Dorsal fin spine | DFS |
Caudal peduncle depth | CPD | Dorsal fin soft ray | DFR |
Caudal peduncle anterior depth | CPAD | Anal fin spine | AFS |
Caudal peduncle length | CPL | Anal fin ray | AFR |
Pre-dorsal length | PDL | Pectoral fin ray | P1FR |
First dorsal fin (longest spine) length | FDFL | Pelvic fin spine | P2FS |
Second dorsal fin (longest ray) length | SDFL | Pelvic fin ray | P2FR |
Caudal fin length | CFL | Pored scale on lateral line | LLS |
Caudal fin notch depth | CFND | Scale above lateral line | SAL |
Anal fin (longest ray) length | AFL | Scale below lateral line | SBL |
Pectoral fin length | P1FL | Upper-limb gill raker | UGR |
Pelvic fin length | P2FL | Lower-limb gill raker | LGR |
Pectoral scaly area length | PSAL | Total gill raker | TGR |
Head length | HL | Abdominal vertebra | AV |
Length-measured cephalic characters | Caudal vertebra | CV | |
Snout length | SNL | Total vertebra | TV |
Orbital diameter | OD | Others | |
Inter-orbital width | IOW | Dorsocephalic scale row | DSR |
Sub-orbital width | SOW | Ventromandibular scale row | VSR |
Post-orbital length | POL | First anal pterygiophore | FAP |
Scale row and paired fin ray counts were made on the left side of the body, whereas gill rakers were counted on the first gill arch on the right side by separating the upper and lower limbs of the gill arch. Because counts of pelvic fin-spine (P2FS) and soft rays (P2FRs) showed no variation (P2FS: 1, P2FRs: 5 in all specimens), these counts were omitted from the statistical analyses. Abdominal and caudal vertebrae were counted, and first anal fin pterygiophore morphology observed from radiographs.
Total numbers of recognizable black or faint spots / dots on the left side of the body and mid-dorsal aspect of the caudal peduncle (Fig.
For a length-measured dimension (LD), a growth-related proportional change pattern is given by the relationship between base dimension [e.g., standard length (SL) or head length (HL)] and the LD proportion (LD / SL or LD / HL). Because the relationship between SL (or HL) and LD is generally expressed by a power regression formula (LD = a SL b) (allometric growth), the following formula was used (LD / SL = a SL b-1). Accordingly, power regressions were applied for the relationships between SL (or HL) and the LD proportions (Table
Regression parameters and correlation between standard length (SL) or head length (HL) and proportions of length-measured dimensions (LD) [SL = a (LD/SL)b, HL = a (LD/HL)b] of three Lateolabrax species.
Regression | Lateolabrax japonicus | Lateolabrax maculatus | Lateolabrax latus | ||||||
a | b | r | a | b | r | a | b | r | |
SL–PAL/SL | 64.42 | 0.004 | 0.092 | 74.89 | -0.026 | -0.524 | 63.90 | 0.008 | 0.270 |
SL–BD/SL | 44.23 | -0.108 | -0.735 | 29.94 | -0.029 | -0.379 | 33.03 | -0.021 | -0.240 |
SL–BWT/SL | 8.78 | 0.075 | 0.471 | 10.71 | 0.048 | 0.455 | 8.43 | 0.079 | 0.466 |
SL–CPD/SL | 16.55 | -0.100 | -0.749 | 11.48 | -0.025 | -0.353 | 11.32 | 0.002 | 0.034 |
SL–CPL/SL | 22.33 | -0.007 | -0.069 | 19.83 | 0.019 | 0.216 | 21.55 | -0.010 | -0.115 |
SL–CPAD/SL | 21.12 | -0.091 | -0.686 | 14.36 | -0.014 | -0.220 | 15.05 | 0.009 | 0.140 |
SL–PDL/SL | 44.01 | -0.041 | -0.574 | 39.76 | -0.029 | -0.513 | 45.07 | -0.039 | -0.711 |
SL–FDFL/SL | 22.72 | -0.081 | -0.407 | 12.40 | 0.008 | 0.065 | 22.22 | -0.086 | -0.541 |
SL–SDFL/SL | 36.65 | -0.201 | -0.762 | 17.05 | -0.068 | -0.443 | 23.31 | -0.091 | -0.485 |
SL–CFL/SL | 32.62 | -0.085 | -0.472 | 17.40 | 0.008 | 0.056 | 28.45 | -0.055 | -0.445 |
SL–CFND/SL | 9.30 | -0.115 | -0.220 | 2.87 | 0.077 | 0.176 | 25.10 | -0.296 | -0.781 |
SL–AFL/SL | 28.14 | -0.142 | -0.713 | 18.56 | -0.061 | -0.474 | 24.60 | -0.096 | -0.553 |
SL–P1FL/SL | 25.19 | -0.070 | -0.581 | 16.98 | -0.010 | -0.109 | 19.79 | -0.024 | -0.270 |
SL–P2FL/SL | 31.24 | -0.101 | -0.701 | 25.47 | -0.073 | -0.682 | 23.84 | -0.040 | -0.357 |
SL–HL/SL | 42.88 | -0.054 | -0.677 | 38.39 | -0.036 | -0.629 | 46.25 | -0.066 | -0.836 |
SL–SNL/SL | 8.23 | 0.002 | 0.047 | 11.42 | -0.087 | -0.664 | 10.91 | -0.027 | -0.456 |
SL–OD/SL | 65.54 | -0.431 | -0.958 | 42.67 | -0.364 | -0.945 | 55.60 | -0.368 | -0.963 |
SL–IOW/SL | 7.55 | -0.020 | -0.173 | 9.31 | -0.064 | -0.601 | 7.75 | -0.010 | -0.082 |
SL–SOW/SL | 2.26 | 0.067 | 0.232 | 1.80 | 0.135 | 0.513 | 2.04 | 0.070 | 0.246 |
SL–POPW/SL | 5.47 | 0.045 | 0.423 | 13.03 | -0.094 | -0.741 | 7.21 | -0.008 | 0.066 |
SL–POL/SL | 15.94 | 0.016 | 0.170 | 13.46 | 0.060 | 0.691 | 19.07 | -0.027 | -0.373 |
SL–UJL/SL | 19.09 | -0.061 | -0.706 | 20.81 | -0.083 | -0.778 | 22.01 | -0.071 | -0.778 |
SL–LJL/SL | 20.51 | -0.058 | -0.700 | 22.29 | -0.084 | -0.782 | 21.66 | -0.052 | -0.629 |
SL–PSAL/SL1 | 8.14 | -0.130 | -0.203 | ||||||
SL–POPW/SNL | 71.07 | 0.030 | 0.314 | 90.56 | 0.031 | 0.222 | 65.79 | 0.020 | 0.149 |
HL–SNL/HL | 20.42 | 0.057 | 0.530 | 28.48 | -0.054 | -0.453 | 24.50 | 0.040 | 0.533 |
HL–OD/HL | 109.60 | -0.400 | -0.946 | 79.68 | -0.338 | -0.945 | 93.74 | -0.323 | -0.950 |
HL–IOW/HL | 18.38 | 0.033 | 0.246 | 23.83 | -0.031 | -0.292 | 17.72 | 0.057 | 0.359 |
HL–SOW/HL | 5.90 | 0.127 | 0.397 | 5.55 | 0.178 | 0.625 | 4.98 | 0.143 | 0.432 |
HL–POPW/HL | 14.81 | 0.090 | 0.690 | 26.66 | -0.022 | -0.240 | 16.41 | 0.061 | 0.418 |
HL–POL/HL | 39.87 | 0.073 | 0.729 | 38.83 | 0.099 | 0.873 | 42.78 | 0.041 | 0.498 |
HL–UJL/HL | 44.57 | -0.009 | -0.139 | 51.77 | -0.049 | -0.667 | 47.53 | -0.006 | -0.109 |
HL–LJL/HL | 48.01 | -0.005 | -0.092 | 55.24 | -0.049 | -0.713 | 47.36 | 0.014 | 0.237 |
Characteristics that changed with growth were evaluated so as to determine if the changes were isometric or allometric, i.e., regressions between SL (or HL) and LD were transformed into natural logarithms (ln) (lnLD = a lnSL + b), and a t test was used to examine slope significance for the null hypothesis (a = 1), according to
To examine inter-specific differences in length-measured characters, regressions between SL (or HL) and LD were also logarithm-transformed (lnLD = a lnSL + b), since most characters showed allometric growth (Table
Regression parameters (slope and intercept) and correlation between logarithm-transformed length-measured characters, together with results of t tests to examine significance of slopes for three Lateolabrax species (null hypothesis, slope = 1).
Regression | Lateolabrax japonicus | Lateolabrax maculatus | Lateolabrax latus | ||||||
Slope | Intercept | t | Slope | Intercept | t | Slope | Intercept | t | |
ln SL–ln PAL | 1.004 | -0.44 | 1.39 | 0.974 | -0.29 | -7.97*** | 1.008 | -0.45 | 3.25* |
ln SL–ln BD | 0.892 | -0.82 | -16.35*** | 0.971 | -1.21 | -5.31*** | 0.979 | -1.11 | -2.87* |
ln SL–ln BWT | 1.075 | -2.43 | 8.05*** | 1.048 | -2.23 | 6.62*** | 1.079 | -2.47 | 6.10*** |
ln SL–ln CPD | 0.900 | -1.80 | -17.04*** | 0.975 | -2.16 | -4.89*** | 1.002 | -2.18 | 0.40 |
ln SL–ln CPL | 0.993 | -1.50 | -1.05 | 1.019 | -1.62 | 2.86* | 0.990 | -1.53 | -1.33 |
ln SL–ln CPAD | 0.909 | -1.55 | -14.28*** | 0.986 | -1.94 | -2.92* | 1.009 | -1.89 | 1.63 |
ln SL–ln PDL | 0.959 | -0.82 | -10.56*** | 0.971 | -0.92 | -7.71*** | 0.961 | -0.80 | -11.72*** |
ln SL–ln FDFL | 0.919 | -1.48 | -6.72*** | 1.008 | -2.09 | 0.85 | 0.914 | -1.50 | -7.45*** |
ln SL–ln SDFL | 0.794 | -0.97 | -17.15*** | 0.932 | -1.77 | -6.31*** | 0.909 | -1.46 | -6.42*** |
ln SL–ln CFL | 0.914 | -1.11 | -7.84*** | 1.008 | -1.75 | 0.70 | 0.974 | -1.35 | -2.55 |
ln SL–ln CFND | 0.880 | -2.35 | -3.41** | 1.077 | -3.55 | 2.22 | 0.704 | -1.38 | -13.88*** |
ln SL–ln AFL | 0.858 | -1.27 | -15.17*** | 0.939 | -1.68 | -6.97*** | 0.904 | -1.40 | -7.67*** |
ln SL–ln P1FL | 0.930 | -1.38 | -10.73*** | 0.990 | -1.77 | -1.41 | 0.976 | -1.62 | -3.25* |
ln SL–ln P2FL | 0.899 | -1.16 | -14.81*** | 0.927 | -1.37 | -12.06*** | 0.960 | -1.43 | -4.42*** |
ln SL–ln HL | 0.946 | -0.85 | -13.87*** | 0.964 | -0.96 | -10.46*** | 0.934 | -0.77 | -17.67*** |
ln SL–ln SNL | 1.002 | -2.50 | 0.67 | 0.913 | -2.17 | -11.57*** | 0.973 | -2.22 | -5.94*** |
ln SL–ln OD | 0.569 | -0.42 | -50.25*** | 0.636 | -0.85 | -37.39*** | 0.632 | -0.59 | -41.41*** |
ln SL–ln IOW | 0.980 | -2.58 | -2.64 | 0.936 | -2.37 | -9.71*** | 0.990 | -2.56 | -0.95 |
ln SL–ln SOW | 1.067 | -3.79 | 3.60** | 1.135 | -4.02 | 7.73*** | 1.070 | -3.89 | 2.94* |
ln SL–ln POPW | 1.033 | -2.84 | 5.68*** | 0.943 | -2.26 | -7.72*** | 0.993 | -2.63 | -0.69 |
ln SL–ln POL | 1.014 | -1.82 | 2.10 | 1.060 | -2.00 | 12.25*** | 0.974 | -1.66 | -4.56*** |
ln SL–ln UJL | 0.939 | -1.66 | -15.04*** | 0.917 | -1.57 | -16.02*** | 0.929 | -1.51 | -14.34*** |
ln SL–ln LJL | 0.942 | -1.58 | -14.74*** | 0.916 | -1.50 | -16.11*** | 0.948 | -1.53 | -9.34*** |
ln SNL–ln POPW | 1.026 | -0.26 | 4.37*** | 1.020 | 0.01 | 1.71 | 1.017 | -0.36 | 4.19*** |
ln HL–ln SNL | 1.057 | -1.59 | 9.41*** | 0.946 | -1.26 | -6.65*** | 1.040 | -1.41 | 7.28*** |
ln HL–ln OD | 0.600 | 0.09 | -44.06*** | 0.662 | -0.23 | -37.38*** | 0.677 | -0.06 | -35.28*** |
ln HL–ln IOW | 1.033 | -1.69 | 3.82** | 0.969 | -1.43 | -3.94** | 1.057 | -1.73 | 4.45*** |
ln HL–ln SOW | 1.127 | -2.83 | 6.52*** | 1.178 | -2.89 | 10.36*** | 1.143 | -3.00 | 5.55*** |
ln HL–ln POPW | 1.090 | -1.91 | 14.36*** | 0.978 | -1.32 | -3.19* | 1.061 | -1.81 | 5.32*** |
ln HL–ln POL | 1.073 | -0.92 | 15.93*** | 1.099 | -0.95 | 23.15*** | 1.041 | -0.85 | 6.62*** |
ln HL–ln UJL | 0.991 | -0.81 | -2.11 | 0.951 | -0.66 | -11.57*** | 0.994 | -0.74 | -1.27 |
ln HL–ln LJL | 0.995 | -0.73 | -0.19 | 0.952 | -0.59 | -13.19*** | 1.014 | -0.75 | 2.81* |
Because some meristic counts tended to increase significantly with growth (Table
Regression parameters (slope and intercept) and correlation between standard length (SL) and meristic counts of three Lateolabrax species (null hypothesis, slope = 0).
Regression | Slope | Intercept | r | t |
Lateolabrax japonicus | ||||
SL–DFS counts | -0.00008 | 12.87 | -0.019 | -0.28 |
SL–DFR counts | -0.00081 | 13.13 | -0.130 | -2.05 |
SL–AFR counts | 0.00048 | 7.56 | 0.089 | 1.34 |
SL–P1FR counts | -0.00047 | 16.96 | -0.086 | -1.30 |
SL–LLS counts | 0.01207 | 77.01 | 0.343 | 5.50*** |
SL–SAL counts | -0.00258 | 15.84 | -0.258 | -3.98** |
SL–SBL counts | 0.00057 | 18.57 | 0.046 | 0.68 |
SL–UGR counts | 0.00111 | 8.63 | 0.126 | 1.90 |
SL–LGR counts | -0.00025 | 17.93 | -0.027 | -0.41 |
SL–TGR counts | 0.00086 | 26.56 | 0.073 | 1.10 |
SL–AV counts | 0.00017 | 16.00 | 0.073 | 0.93 |
SL–CV counts | -0.00068 | 20.02 | -0.108 | -1.38 |
SL–TV counts | -0.00051 | 36.02 | -0.083 | -1.80 |
SL–Dot counts | -0.02297 | 12.69 | -0.198 | -2.90* |
Lateolabrax maculatus | ||||
SL–DFS counts | -0.00046 | 12.95 | -0.153 | -2.00 |
SL–DFR counts | -0.00028 | 13.03 | -0.066 | -0.86 |
SL–AFS counts | 0.00008 | 2.98 | 0.104 | 1.36 |
SL–AFR counts | 0.00097 | 7.34 | 0.217 | 2.88 |
SL–P1FR counts | 0.00079 | 16.33 | 0.190 | 2.50 |
SL–LLS counts | 0.00261 | 73.45 | 0.099 | 1.30 |
SL–SAL counts | 0.00008 | 15.52 | 0.009 | 0.24 |
SL–SBL counts | 0.00477 | 18.17 | 0.409 | 5.72*** |
SL–UGR counts | 0.00139 | 6.40 | 0.173 | 2.24 |
SL–LGR counts | 0.00330 | 14.70 | 0.507 | 7.49*** |
SL–TGR counts | 0.00469 | 21.11 | 0.408 | 5.68*** |
SL–AV counts | -0.00026 | 15.97 | -0.135 | -1.67 |
SL–CV counts | 0.00022 | 19.00 | 0.089 | 1.09 |
SL–TV counts | 0.00003 | 34.97 | -0.012 | -0.02 |
SL–Spot counts | 0.02333 | 33.89 | 0.126 | 1.62 |
Lateolabrax latus | ||||
SL–DFS counts | -0.00026 | 13.05 | -0.092 | -1.08 |
SL–DFR counts | -0.00041 | 15.11 | 0.011 | -1.20 |
SL–AFS counts | -0.00002 | 3.00 | 0.001 | -0.34 |
SL–AFR counts | 0.00026 | 9.06 | 0.002 | 0.55 |
SL–P1FR counts | -0.00026 | 16.20 | 0.004 | -0.73 |
SL–LLS counts | 0.00264 | 72.91 | 0.169 | 1.99 |
SL–SAL counts | -0.00063 | 13.86 | -0.079 | -0.92 |
SL–SBL counts | -0.00013 | 15.79 | -0.014 | -0.16 |
SL–UGR counts | -0.00045 | 6.83 | -0.072 | -0.83 |
SL–LGR counts | -0.00109 | 17.11 | -0.176 | -2.07 |
SL–TGR counts | -0.00154 | 23.94 | -0.166 | -1.95 |
SL–AV counts | 0.00004 | 16.03 | 0.018 | 0.22 |
SL–CV counts | -0.00005 | 19.92 | -0.014 | -0.17 |
SL–TV counts | 0.00001 | 35.95 | -0.004 | -0.05 |
SL–Dot counts | -0.06278 | 24.74 | -0.365 | -4.53*** |
In the above statistical inferences, due to multiple tests being applied simultaneously in each case, multiple comparisons were introduced for the t test results, risk percentages for the t values being corrected according to total test counts, using the Holm-Bonferroni method (
In the three Lateolabrax species, slopes of the logarithm-transformed regressions were significantly different from 1 (allometric growth) for most characters (Table
Relationships between standard length and proportions of some length-measured body characters which exhibited prominent plot separation among three Lateolabrax species. For character abbreviations, see Figure
Similar patterns of growth-related proportional changes common to the three species were observed for some characters, viz., significant positive allometric growth (proportions increased with growth) in body width and significant negative allometric growth (proportions decreased with growth) in head (HL) and pre-dorsal length (PDL), and second dorsal, anal and pelvic fin (longest ray) lengths (SDFL, AFL and P2FL), although patterns of the regression curves or plot distributions for the three species sometimes varied from one another (Figs
For length-measured dimensions (LD) of cephalic characters, SL-based (SL–LD / SL) and HL-based relationships (HL–LD / HL) are illustrated in pairs with multiple specific plots in Figure
Growth-related proportional change patterns based on SL and HL were inconsistent with each other for some characters in L. japonicus and L. latus, e.g., snout length (SNL) of L. japonicus was isometric and positively allometric for SL and HL, respectively; that of L. latus was negatively and positively allometric for SL and HL, respectively (Fig.
As well as some body characters, specific proportional change patterns were recognized for some characters, e.g., SL-based relationships of POPW, exhibiting isometric growth in L. japonicus, and positive and negative allometric growth in L. maculatus and L. latus, respectively (Fig.
The relationship between SL and pectoral scaly area length (PSAL) in L. latus was well fitted to a power regression (like many other body and cephalic length-measured characters), the PSAL / SL proportion gradually decreasing with growth (Fig.
Plot separation of L. latus from the other two species was prominent for vertical body dimensions of body depth (BD), caudal peduncle depth (CPD) and caudal peduncle anterior depth (CPAD), L. japonicus and L. maculatus both showing significant negative allometric growth, the degree of relative decrease being especially acute in the former. Although BD of L. latus showed slight negative allometric growth, CPD and CPAD were regarded as isometric (Fig.
Plot separation of first and second dorsal (FDFL and SDFL), caudal (CFL) and pectoral (P1FL) fin lengths was also apparent between L. japonicus and L. maculatus (Fig.
Upward plot separation of L. latus from the other two species was prominent for SNL and upper and lower jaw lengths (UJL and LJL), there being almost no overlap with L. maculatus and only modest overlap with L. japonicus (Fig.
On the other hand, plot separation between L. japonicus and L. maculatus was prominent for SNL, POPW and POL (Fig.
POPW proportional to SNL is shown graphically in Figure
The t tests of regressions between SL and meristic counts (null hypothesis, slope = 0) proved significant for scales on (LLS) and above the lateral line (SAL) in L. japonicus, and scales below the lateral line (SBL) and gill raker counts [lower limb and total (LGR and TGR, respectively)] in L. maculatus (Table
Figure
Some examples of L. japonicus and L. latus had small and fine dots, respectively, on the lateral body region (Fig.
Post-juvenile specimens (> ca. 70 mm SL) of the three Lateolabrax species had a pair of scale rows (dorsocephalic scale rows, DSRs) extending forward from the inter-orbital area, which was densely covered with fine scales (Fig.
Squamation on dorsal head regions of Lateolabrax japonicus (A, B), L. maculatus (C, D) and L. latus (E, F). Thick arrows indicate anterior nostrils, thin arrows indicate anterior edges of dorsocephalic scale rows. A KAUM–I. 93435 (137.0 mm SL) B BSKU 100803 (265.2 mm SL) C uncatalogued specimen (104.9 mm SL) D BSKU 100773 (254.2 mm SL) E KAUM–I. 39058 (114.2 mm SL) F KPM-NI 24255 (240.1 mm SL).
Some individuals of the three Lateolabrax species had a pair of ventromandibular scale rows (VSRs), VSR status by body size being summarized in Table
Frequencies (%) of ventromandibular scale row status in three Lateolabrax species.
SL range (mm) | Anterior part | Posterior part | ||||
Present | Vestigial | Absent | Present | Vestigial | Absent | |
Lateolabrax japonicus | ||||||
≤100 | 0.0 | 0.0 | 100.0 | 0.0 | 0.0 | 100.0 |
100–200 | 0.0 | 14.3 | 85.7 | 10.7 | 21.4 | 67.9 |
200–300 | 5.0 | 25.0 | 70.0 | 35.0 | 30.0 | 35.0 |
300–400 | 5.3 | 26.3 | 68.4 | 31.6 | 57.9 | 10.5 |
>400 | 25.0 | 50.0 | 25.0 | 37.5 | 62.5 | 0.0 |
Lateolabrax maculatus | ||||||
≤100 | 0.0 | 0.0 | 100.0 | 0.0 | 0.0 | 100.0 |
100–200 | 0.0 | 0.0 | 100.0 | 0.0 | 0.0 | 100.0 |
200–300 | 0.0 | 18.2 | 81.8 | 22.7 | 54.5 | 22.7 |
300–400 | 5.6 | 55.6 | 38.9 | 55.6 | 27.8 | 16.7 |
>400 | 12.1 | 51.5 | 36.4 | 84.8 | 15.2 | 0.0 |
Lateolabrax latus | ||||||
≤100 | 0.0 | 13.3 | 86.7 | 6.7 | 13.3 | 80.0 |
100–200 | 70.5 | 18.0 | 11.5 | 49.2 | 19.7 | 31.1 |
200–300 | 95.1 | 4.9 | 0.0 | 97.6 | 2.4 | 0.0 |
300–400 | 100.0 | 0.0 | 0.0 | 100.0 | 0.0 | 0.0 |
>400 | 100.0 | 0.0 | 0.0 | 100.0 | 0.0 | 0.0 |
All three Lateolabrax species had a well-developed first anal pterygiophore (FAP), which comprised a short thin plate-like anterior part and a long thick spiny posterior part (Fig.
Radiographs of first anal pterygiophores in Lateolabrax japonicus (A–D), L. maculatus (E–H) and L. latus (I–L), according to body size by species. A KAUM–I. 82683 (65.6 mm SL) B BSKU 100883 (96.8 mm SL) C BSKU 100756 (252.4 mm SL) D KPM-NI 9697 (317.0 mm SL) E uncatalogued specimen (58.4 mm SL) F TKPM-P 1655-6 (95.2 mm SL) G BSKU 100771 (250.8 mm SL) H KPM-NI 9686 (364.0 mm SL) I KAUM–I. 1895-4 (70.3 mm SL) J KAUM–I. 64737 (SL 94.2 mm) K KPM-NI 24650 (265.4 mm SL) L KAUM–I. 57963 (342.0 mm SL).
Analyses of covariance (ANCOVA) for regressions of logarithm-transformed length-measured characters by pairwise comparisons for the three Lateolabrax species indicated significant differences in the slopes or intercepts of all such characters (Table
Results of analysis of covariance (ANCOVA) (t test) to compare regression parameters of logarithm-transformed length-measured characters between three Lateolabrax species.
Regression | L. japonicus × L. maculatus | L. japonicus × L. latus | L. maculatus × L. latus | |||
---|---|---|---|---|---|---|
Slope | Intercept | Slope | Intercept | Slope | Intercept | |
ln SL–ln PAL | 7.00*** | – | 1.03 | 6.61*** | 7.08*** | – |
ln SL–ln BD | 9.03*** | – | 8.16*** | – | 0.91 | 26.57*** |
ln SL–ln BWT | 2.34 | 6.92*** | 0.22 | 2.58* | 2.22 | 9.23*** |
ln SL–ln CPD | 9.51*** | – | 10.97*** | – | 3.26 | 26.59*** |
ln SL–ln CPL | 2.81 | 2.97* | 0.29 | 9.35*** | 2.69 | 11.00*** |
ln SL–ln CPAD | 9.41*** | – | 10.18*** | – | 2.91 | 36.84*** |
ln SL–ln PDL | 2.22 | 11.60*** | 0.25 | 10.07*** | 1.83 | 21.83*** |
ln SL–ln FDFL | 5.75*** | – | 0.30 | 5.13*** | 5.99*** | – |
ln SL–ln SDFL | 8.52*** | – | 6.02*** | – | 1.23 | 18.51*** |
ln SL–ln CFL | 6.05*** | – | 3.45* | – | 1.86 | 16.84*** |
ln SL–ln CFND | 3.99** | – | 3.49* | – | 7.37*** | – |
ln SL–ln AFL | 6.28*** | – | 2.88 | 12.25*** | 2.25 | 11.23*** |
ln SL–ln P1FL | 6.17*** | – | 4.24** | – | 1.26 | 12.21*** |
ln SL–ln P2FL | 3.07 | 9.89*** | 5.18*** | – | 2.96 | 16.28*** |
ln SL–ln HL | 3.45* | – | 1.82 | 5.42*** | 5.30*** | – |
ln SL–ln SNL | 9.97*** | – | 3.68* | – | 5.53*** | – |
ln SL–ln OD | 5.26*** | – | 4.66*** | – | 0.26 | 28.99*** |
ln SL–ln IOW | 4.29** | 0.73 | 10.95*** | 4.27** | – | |
ln SL–ln SOW | 2.64 | 7.96*** | 0.08 | 5.20*** | 2.15 | 12.35*** |
ln SL–ln POPW | 10.37*** | – | 3.61* | – | 4.15** | – |
ln SL–ln POL | 5.43*** | – | 3.90** | – | 10.54*** | – |
ln SL–ln UJL | 3.42* | – | 1.44 | 25.97*** | 1.55 | 26.46*** |
ln SL–ln LJL | 4.05** | – | 0.79 | 22.93*** | 3.76* | – |
ln SNL–ln POPW | 0.48 | 33.61*** | 0.76 | 27.56*** | 0.18 | 44.42*** |
ln HL–ln SNL | 11.07*** | – | 1.82 | 23.86*** | 7.76*** | – |
ln HL–ln OD | 4.84*** | – | 5.29*** | – | 1.02 | 28.82*** |
ln HL–ln IOW | 5.47*** | – | 1.52 | 7.78*** | 5.92*** | – |
ln HL–ln SOW | 1.95 | 9.36*** | 0.46 | 6.42*** | 1.14 | 15.08*** |
ln HL–ln POPW | 12.17*** | – | 2.40 | 2.74* | 6.34*** | – |
ln HL–ln POL | 4.04** | – | 4.15** | – | 7.64*** | – |
ln HL–ln UJL | 6.89*** | – | 0.38 | 22.63*** | 6.19*** | – |
ln HL–ln LJL | 7.92*** | – | 2.84 | 3.37** | 9.71*** | – |
Although the Mann-Whitney U tests for pairwise comparisons of meristic characters of the three species found significant differences in many, significance was not apparent for others, including counts of vertical fin rays [dorsal fin spines (DFSs), DFRs and AFRs] between L. japonicus and L. maculatus, and vertebrae [abdominal vertebrae (AVe), CVe and TVe] between L. japonicus and L. latus (Table
Results of the Mann-Whitney U test (z values) to compare meristic counts between three Lateolabrax species.
Character | L. japonicus × L. maculatus | L. japonicus × L. latus | L. maculatus × L. latus |
DFS counts | 0.37 | 3.00* | 3.64** |
DFR counts | 0.12 | 16.22*** | 15.60*** |
AFS counts | 0.00 | 1.29 | 0.64 |
AFR counts | 1.39 | 14.64*** | 14.11*** |
P1FR counts | 5.69*** | 10.62*** | 5.77*** |
LLS counts | 11.53*** | 13.74*** | 0.89 |
SAL counts | 2.04 | 11.50*** | 11.47*** |
SBL counts | 3.57** | 14.43*** | 13.88*** |
UGR counts | 14.31*** | 14.58*** | 0.65 |
LGR counts | 15.45*** | 8.83*** | 11.76*** |
TGR counts | 16.54*** | 15.13*** | 7.81*** |
AV counts | 4.23*** | 0.64 | 4.15*** |
CV counts | 13.58*** | 0.01 | 13.45*** |
TV counts | 14.82*** | 0.73 | 14.09*** |
Standard errors (SEs) for regression lines between logarithm-transformed SL and length-measured characters, and between SL and meristic characters are summarized in Table
Standard errors for morphological character regressions of three Lateolabrax species.
Regression | L. japonicus | L. maculatus | L. latus |
ln SL–ln PAL | 0.024 | 0.029 | 0.015 |
ln SL–ln BD | 0.057 | 0.050 | 0.043 |
ln SL–ln BWT | 0.080 | 0.064 | 0.077 |
ln SL–ln CPD | 0.051 | 0.046 | 0.036 |
ln SL–ln CPL | 0.055 | 0.060 | 0.044 |
ln SL–ln CPAD | 0.055 | 0.044 | 0.031 |
ln SL–ln PDL | 0.033 | 0.033 | 0.020 |
ln SL–ln FDFL | 0.103 | 0.084 | 0.068 |
ln SL–ln SDFL | 0.094 | 0.096 | 0.084 |
ln SL–ln CFL | 0.085 | 0.095 | 0.068 |
ln SL–ln CFND | 0.273 | 0.299 | 0.119 |
ln SL–ln AFL | 0.079 | 0.079 | 0.074 |
ln SL–ln P1FL | 0.056 | 0.063 | 0.045 |
ln SL–ln P2FL | 0.058 | 0.053 | 0.054 |
ln SL–ln HL | 0.034 | 0.031 | 0.022 |
ln SL–ln SNL | 0.044 | 0.067 | 0.027 |
ln SL–ln OD | 0.074 | 0.087 | 0.053 |
ln SL–ln IOW | 0.066 | 0.059 | 0.065 |
ln SL–ln SOW | 0.160 | 0.155 | 0.140 |
ln SL–ln POPW | 0.050 | 0.058 | 0.060 |
ln SL–ln POL | 0.057 | 0.044 | 0.035 |
ln SL–ln UJL | 0.035 | 0.046 | 0.029 |
ln SL–ln LJL | 0.034 | 0.046 | 0.033 |
ln SNL–ln POPW | 0.052 | 0.097 | 0.068 |
SL–DFS counts | 0.515 | 0.424 | 0.299 |
SL–DFR counts | 0.649 | 0.607 | 0.420 |
SL–AFS counts | 0.000 | 0.109 | 0.086 |
SL–AFR counts | 0.626 | 0.629 | 0.581 |
SL–P1FR counts | 0.624 | 0.589 | 0.432 |
SL–LLS counts | 3.828 | 3.725 | 1.623 |
SL–SAL counts | 1.117 | 0.614 | 0.837 |
SL–SBL counts | 1.394 | 1.516 | 1.009 |
SL–UGR counts | 1.020 | 1.131 | 0.659 |
SL–LGR counts | 1.073 | 0.804 | 0.644 |
SL–TGR counts | 1.366 | 1.507 | 0.963 |
SL–AV counts | 0.155 | 0.279 | 0.191 |
SL–CV counts | 0.420 | 0.370 | 0.336 |
SL–TV counts | 0.426 | 0.414 | 0.333 |
The present study revealed that most body proportions of the three Lateolabrax species change with growth (Table
On the other hand, taxonomic and related literature on Lateolabrax have commonly noted the diagnostic importance of ranges and / or averages of body proportions (e.g.,
Proportional range comparisons of head length [HL, % of standard length (SL)] in Lateolabrax japonicus (upper graph, axis labelled BD / SL) and orbital diameter (OD, % of HL) in L. maculatus (lower graph, axis labelled OD / HL) in the present study and previous literature. Data based on A present study B
Differing growth-related proportional change patterns in the three Lateolabrax species include pre-anus length (PAL) (Fig.
As in many other fishes (
Growth-related proportional change patterns of length-measured cephalic characters (based on SL and HL) were sometimes inconsistent in L. japonicus and L. latus (Fig.
The proportional values (percentages) of proportions subject to allometric growth are correlated with the base dimension (e.g., SL and HL). In Figure
Because most of the length-measured characters of the three Lateolabrax species were subject to allometric growth (Table
Counts of pored scales on the lateral line (LLSs) and scales above the lateral line (SALs) tended to increase and decrease with growth, respectively, in L. japonicus (Fig.
The growth-related status of dots / spots on the lateral body region also varied among the three Lateolabrax species. In L. japonicus and L. latus, although dots appeared in some smaller specimens (up to 260.6 and 254.8 mm SL, respectively), they disappeared with growth (Fig.
The proportional growth-related change pattern of pectoral scaly area length (PSAL) in L. latus closely fitted a power regression (Fig.
Lateolabrax latus is typically characterized by a deeper body, represented by BD and CPD. However, neither character provides unequivocal identification due to the range overlap for proportional BD and CPD between L. latus and L. japonicus (
The CPAD proportion may be a useful feature for specific identification, since it can also be determined from illustrations and photographs of Lateolabrax species. For instance, an illustration of “L. japonicus (as Perca-labrax japonicus)” in Fauna Japonica (
In addition to caudal peduncle stoutness in L. latus,
Caudal fin notch depth (CFND) has been recently proposed as a new character for distinguishing L. latus from the other two species, the former having a shallower CFND than the others (
Among the length-measured cephalic characters of L. latus, plot separation of that species from the others was marked for snout length (SNL) (Fig.
The UJL and LJL plots for all three species (SL-based relationships) were well clustered around their regression curves (high negative allometry), but could not be distinguished from one another vertically (Fig.
The original description of L. latus included several diagnostic meristic characters, including counts of DFRs, AFRs and SBLs (
In addition to length-measured and meristic characters in the original description of L. latus a further diagnostic feature proposed was the possession of ventromandibular scale rows (VSRs) (
The diagnosis accompanying the original description of L. latus included ventral (pelvic fins) generally dusky, unlike in L. japonicus (
Recent keys for identification of L. japonicus and L. maculatus have adopted SNL, that of L. maculatus supposedly being relatively shorter than that of the former (
On the other hand, post-orbital preopercular width (POPW) is a notable dimension, showing a contrasting pattern to SNL, i.e., plots of proportional POPW in small (< 200 mm SL) L. maculatus shifted upward and separated completely from those of similar sized L. japonicus (border levels ca. 7.5% and 23% for SL- and HL-based relationships, respectively), although larger specimens (> 200 mm SL) of the two species had some overlap due to the relative decrease of POPW with growth (highly negative allometry) in the former (Fig.
Proportional differences between L. japonicus and L. maculatus were also apparent in many of the fin lengths (first and second dorsal, caudal and pectoral), proportions of the former being distinctly greater than those of the latter in smaller specimens (< ca. 200 mm SL), although plots of the two species overlapped in the larger size class (> ca. 200 mm SL), due to the relative fin lengths decreasing and not changing with growth in the former and latter species, respectively (Fig.
Although
On the other hand, caudal and total vertebral counts (CV and TV, respectively), in which dominant counts were almost completely replaced between L. japonicus and L. maculatus (20 and 19 CVe, 36 and 35 TVe, for the former and latter, respectively) (Fig.
Although L. maculatus typically possessed many black spots on the body, individual spot counts and patterns varied considerably (
A morphological difference in the first anal pterygiophore (FAP) between L. japonicus and L. maculatus was initially noted by
Standard errors (SEs) for the length-measured and meristic character regressions, which indicated degrees of morphological variation, were generally lowest in L. latus (Table
The present study demonstrated a number of growth-related morphological changes in the three Lateolabrax species, including some new key characters for identification. Despite the number of taxonomic descriptions and studies of Lateolabrax, such features have remained obscure due to the limited numbers of specimens examined and an inherent belief that fish morphology is stable regardless of growth, notwithstanding some recent unique allometric approaches to fish morphology and taxonomy (e.g.,
a1 | Caudal peduncle anterior depth [% of standard length (SL)] > 15%. Snout length (% of SL) > 9%. Upper and lower jaw length [% of head length (HL)] > 45% and 49%, respectively. Dorsal fin rays 15–16 [rarely 14 (7.4%)]. Anal fin rays 9 (usually)–11 [rarely 8 (11.0%)] | Lateolabrax latus |
a2 | Caudal peduncle anterior depth (% of SL) ≤ 15%. Snout length (% of SL) ≤ 9%. Upper and lower jaw length (% of HL) ≤ 45% and 49%, respectively. Dorsal fin rays 14 or fewer. Anal fin ray counts 8 or fewer (rarely 9) | b |
b1 | Post-orbital preopercular width (POPW) [% of snout length (SNL)] < 90% [POPW (% of SL) < 7.5% in specimens ≤ 200 mm SL; SNL (% of SL) > 7.7% in specimens > 200 mm SL]. Caudal vertebrae 20 (usually)–21 [rarely 19 (13.5%)]; total vertebrae 36 (usually)–37 [rarely 35 (13.5%)]. First anal pterygiophore modestly arched in specimens ≥ 90 mm SL. Spots / dots absent on body in specimens > 260 mm SL (although some specimens ≤ 260 mm SL have some dots restricted to upper part than lateral line) | Lateolabrax japonicus |
b2 | Post-orbital preopercular width (POPW) [% of snout length (SNL)] ≥ 90% [POPW (% of SL) ≥ 7.5% in specimens ≤ 200 mm SL; SNL (% of SL) ≤ 7.7% in specimens > 200 mm SL]. Caudal vertebrae 18–19 (usually) [rarely 20 (9.2%)]; total vertebrae 34–35 (usually) [rarely 36 (6.6%)]. First anal pterygiophore straight. Usually many clear black spots on lateral and dorsal body regions (usually even on lower part than lateral line) | Lateolabrax maculatus |
The author is grateful to Drs. Hiroshi Senou (KPM), Hiroyuki Motomura (KAUM) and Hiromitsu Endo (BSKU) for the loan of registered specimens of Lateolabrax species. Dr. Motomura also enabled registration of additional L. japonicus specimens to KAUM. Dr. Senou provided some photographs of fresh KPM specimens. Mr. Taiga Naito (BSKU) assisted with radiography and some measurements. Dr. Shi Dong (Tianjin Normal University) advised on translation of some Chinese literature. Dr. Endo, Mr. Hirokazu Kishimoto (Shizuoka City, Japan), Mr. Taiji Kurozumi (Natural History Museum and Institute, Chiba), Dr. Brian L. Sidlauskas (Oregon State University) and Mr. Ikuo Wakabayashi (Wildlife Research Society of Shima Peninsula) helped with provision of literature. Finally, I wish to thank Dr. Graham S. Hardy (Ngunguru, New Zealand) for checking the manuscript.