Allometric variation and sexual dimorphism in <i>Lycodes yamatoi </i>Toyoshima, 1985 (Perciformes: Zoarcidae) from the Sea of Japan
A detailed analysis of allometric variation and sexual dimorphism in Lycodes yamatoi (Perciformes: Zoarcidae) was performed using an original method proposed by the authors. Allometric growth of not only plastic, but also some meristic characters (the number of teeth on bones of the mouth apparatus and the number of gill rakers on the first gill arc) was observed. Positive allometry was found for most of the morphological features of L. yamatoi (proportions of the head and anterior body region). For the rest of the characters analyzed, we obtained negative allometry (length of the paired fin rays and length of the caudal fin rays, bony interorbital width, isthmus width) and isometry (standard length, preanal length, head width on the vertical with neck). Young fish of both sexes had no significant differences in either plastic or meristic features. Adult male and female L. yamatoi reliably differed in features of the head complex, the head length, and the predorsal and prepectoral lengths correlating to the head length. The most valuable indices for sex discrimination are the predorsal and prepectoral lengths and the relative maxilla length.