Biology and egg morphology of the Dalmatian barbelgudgeon Aulopyge huegeli, an endangered endemic species in Croatia

Abstract

This paper describes patterns of annual and diurnal activity in the endangered endemic cyprinid Aulopyge huegeli from Croatia. The species is largely nocturnal. Spawning in the laboratory begins at temperatures of 20°C. Aulopyge huegeli is a rock and gravel brood hider. The female deposits eggs in various fissures with a special ovipositor. The eggs are whitish and have a diameter between 1.5 and 2 mm. The zona radiata is relatively thin (3.2-5.5 μm) and provides the eggs with the necessary plasticity. The surface is covered with an attaching substance and with short attachment extension around the vegetal pole. This correlates with features of the spawning microhabitats. Aulopyge huegeli has a very small micropyle which consists of a pit with a diameter of 7.5 μm and a canal with a diameter of 2.5 μm (micropyle type I).