Yokogawa K.,13 5 Higashihama
Ichthyological Research | Year: 2013
Morphological variations in bluegill, Lepomis macrochirus, including growth-related changes, sexual dimorphism and morphological differences between populations in different habitats, were examined in samples from three reservoirs in Kagawa, Japan. Body measurements demonstrated frequent growth-related proportional changes, particularly in body depth, body width, caudal peduncle length and head length, which all showed relative increases, whereas first dorsal fin length, caudal fin length and orbital diameter became relatively shorter. Body weight increased relatively with growth, with relative growth coefficients of 3. 339-3. 454 for regressions between total length and body weight. Such body weight increases were likely due to the relative increases in body depth and width, and caudal peduncle depth. Although counts of fin spines, fin rays and gill rakers did not change with growth, those of scales tended to increase. Males were significantly larger than females in body depth, caudal peduncle length, head length and body weight. Sexual dimorphism was also apparent in body coloration during the breeding season. In addition, a number of morphological differences were observed between individuals from different habitats. © 2012 The Ichthyological Society of Japan.
Yokogawa K.,13 5 Higashihama |
Watanabe K.,Fisheries Research Institute
Ichthyological Research | Year: 2011
Squamation and scale morphology were examined in two closely related species, Pleuronichthys cornutus and P. japonicus, in order to establish the unambiguous characters to clearly separate the two species. Scale counts on the lateral body surface were also examined, with new count definitions proposed. Both the longitudinal and vertical scale rows followed essentially regular patterns in P. cornutus, whereas the longitudinal scale rows were occasionally irregular in P. japonicus. Scales were basically fan-shaped and oval in P. cornutus and P. japonicus, respectively, although considerable variation in scale shape was apparent in both species. The blind side scales of P. cornutus had sharp posterior margins, whereas those of P. japonicus had round ones. Scale length (scales on the ocular side, area above the lateral line) in P. japonicus was relatively greater than in P. cornutus, a plot of total length versus scale length separating the species completely. Measurements of many ocular side scales from the area above the lateral line indicated high intraspecific variance in both species, being particularly prominent in P. cornutus. Nevertheless, considerable scale measurement differences were found between the two species in some body areas, supported by principal component analysis. Longitudinal and vertical row scale counts were higher in P. cornutus than in P. japonicus, with the ranges of central longitudinal scales (88-103 vs. 75-86) and scales below the lateral line counts (59-74 vs. 47-57), respectively, not overlapping between the species. The scale count difference could be caused by the difference of the scale size between the two species. The study demonstrated that the two Pleuronichthys species can be readily distinguished on the basis of scale morphology and size, in addition to scale counts. © 2010 The Ichthyological Society of Japan.
Yokogawa K.,13 5 Higashihama
Ichthyological Research | Year: 2015
Morphological differences, including growth-related changes, were examined in two closely related East Asian flatfish species, Pleuronichthys lighti and Pleuronichthys cornutus. Body measurements of both species indicated frequent growth-related proportional changes, head length, pelvic fin length (both fins), eye diameter (both eyes), inter-orbital ridge length and the lengths of both jaws all showing relative decreases with growth. On the other hand, whereas caudal fin length became relatively shorter and snout length relatively greater with growth in P. lighti, those proportions remained unchanged with growth in P. cornutus. Conversely, although body depth became relatively greater and the longest dorsal and anal fin rays relatively shorter with growth in P. cornutus, those proportions remained unchanged with growth in P. lighti. Counts of scales below the lateral line and gill rakers both tended to increase with growth in P. cornutus, but remained stable in P. lighti. New key characters to distinguish between the two species included ocular side pectoral fin length and the area ratio between the upper and lower eyes. The ocular side pectoral fin of P. cornutus was generally longer than in P. lighti, with plots of the fin proportions in the two species showing modest separation. In addition, because both the horizontal and vertical diameters of the upper eye of P. cornutus were generally greater than those of P. lighti, graphical representation of the relationship between the upper and lower eye areas showed almost complete separation of the two species. © 2015, The Ichthyological Society of Japan.
PubMed | 13 5 Higashihama
Type: Journal Article | Journal: Zootaxa | Year: 2016
Because of the taxonomic confusion, including misapplication of their scientific names, resulting from the morphological similarity of two East Asian flatfish species, Pleuronichthys lighti Wu, 1929 and Pleuronichthys cornutus (Temminck & Schlegel, 1846), both species are redescribed, with particular emphasis on some new key characters. New common names are proposed for each species.
Yokogawa K.,13 5 Higashihama |
Ogihara G.,Kagoshima University |
Watanabe K.-I.,65 10 Yakami Kitabun
Ichthyological Research | Year: 2014
The taxonomy of two species of Pleuronichthys from East Asia was re-examined on the basis of scale characteristics. The lectotype of Pleuronichthyscornutus (Temminck and Schlegel 1846) was shown to be conspecific with Pleuronichthysjaponicus Suzuki, Kawashima and Nakabo 2009, being characterized by oval scales, a greater exposed scale area and lower scale counts than a second species, formerly recognized as P. cornutus, but to which Pleuronichthyslighti Wu 1929, formerly considered a junior synonym of P. cornutus, should now be applied. Accordingly, P. japonicus is now considered a junior synonym of P. cornutus. © 2014, The Ichthyological Society of Japan.