The gill apparatus consists of five
pairs of gill arches. The branchial arches I, II, III
and IV have ventral and dorsal segments, while the
branchial arch V contains only a ventral one. The
pharyngeal dental apparatus is located in the caudal
portion of the oropharynx cavity and consists of a
ventral triangular plate and two dorsal oval dental
plates, both with unciform denticles (Fig. 1A, 1B).