Description of the Smooth Lumpsucker Aptocyclus ventricosus (Cyclopteridae) Larvae from Bays of the South-Eastern Coast of Kamchatka Peninsula

The article presents an illustrated description of early larvae of the smooth lumpsucker Aptocyclus ventricosus from Avacha Bay and Vilyuchinskaya Bay in southeastern coast of Kamchatka. The larvae differ from previously described larvae from Japanese and Korean waters in their earlier development: the urostyle bending, the formation of fin rays, and the development of pigmentation occur earlier. The growth of the larvae is uneven. The head and torso increase in relation to the length of the body, while the tail part practically does not grow. Eye diameter, maxillary length, and the length of the pectoral fin rays relatively decrease. The first dorsal fin is difficult to distinguish, which can cause difficulties in the larva diagnoses. The larvae are coastal, lead an attached lifestyle.