New Data on Spawning Site and Group Egg Laying of Onychodactylus fischeri (Boulenger, 1886) (the Southern Sikhote-Alin Range, Russia)

Abstract

At the end of May, a permanent spawning site of Onychodactylus fischeri was first discovered in the gravel-stony layer under the bottom of a small river valley in the upward flows of subsurface alluvial waters (upper reaches of the Pravaya Sokolovka River, the Sikhote-Alin Range, Chuguevka rayon, Primorsky Krai). This place was located at an altitude of 650 m a.s.l. in mixed coniferous-broad-leaved forest in a narrow river valley. The primary spawning site lay beneath the bottom of a small water body that was two meters away from the main river course. The water in the breeding ground was slightly acidic and slightly mineralized. The local population of O. fischeri begins to reproduce in the end of May, when the water temperature inside the site reaches 6.1 – 7.9°C. This site had been used for egg laying on multiple occasions. We found 72 clutches attached to several small stones (n = 11). There were no large cavities between the stones, only narrow gaps. There were two recently laid clutches, 26 clutches in the late stages of embryogenesis, already empty sacs and fragments of old mucous stalks. O. fischeri lays paired egg sacs measuring 35.4 ± 1.9 mm (34.5 – 38.15; n = 3) in length. Egg arrangement in clutches of O. fischeri was varying: in one (or in two) rows in both sacs, or in one row — in one sac and in two — in the other. The mean number of eggs in each sac was 6.8 ± 1.3 (4 – 10; n = 55), the mean number of eggs in the clutch — 13.6 ± 2.2 (9 – 17; n = 27), the egg diameter — 8.08 ± 0.6 mm (6.71 – 8.9; n = 19). For the first time we recorded the otter (Lutra lutra) actively hunting adult O. fischeri. In late May – early July it preyed upon salamanders near the spawning site. The otter ate heads and bodies of O. fischeri but not tails. Perhaps, a high concentration of muciparous glands with poisonous secretion in the tails prevented the predator from eating them.