Skin structure in six dragonet species (Gobiesociformes; Callionymidae): interspecific differences in glandular cell types and mucus secretion

A comparative histological and histochemical study on the skin structure of six dragonet species, Synchiropus splendidus, Synchiropus picturatus, Synchiropus ocellatus, Repomucenus richardsonii, Callionymus decoratus and Callionymus risso showed that the epidermis of all species was rich in mucous cells (globlet cells), varying in distribution and elaboration among species. A second, distinctive, cell type, the sacciform cell, was also found in S. splendidus and S. picturatus. The secretions of these two cell types probably serve several functions, including those related to predation and the close contact that these species have with the substratum. The differences in type, elaboration and distribution of the cells suggested a pattern among the six callionymid species, in relation to habitat and body colouration differences.