SEM Observation on the Mouth Tube and Preoral Sting of Argulus coregoni THORELL and Argulus japonicus THIELE (Crustacea: Branchiura)

Abstract

The mouth-parts of Argulus coregoni and A. japonicus are described based on SEM observation. A smooth upper lip and a rugose lower lip with small rows of teeth form the mouth opening. Two types of sensilla lie on the lips around the opening. Mandibles and labial spines are found in the buccal cavity. The preoral sting has a globular tip, a ventral, subterminal glandular pore and a dorsal, subterminal minute pore possibly of sensory in function. Some differences in the buccal folds and a pair of spines on the mouth tube are found between the adults and larvae of A. coregoni. But there are no significant differences in the mouth-parts between the two species.