Fine structure and distribution of epidermal projections associated with taste buds on the oral papillae in some loricariid catfishes (Siluroidei: Loricariidae)

Two morphologically distinct structures occur on the surfaces of the oral papillae in several loricariid catfish species; namely, (1) typical vertebrate taste buds composed of receptor and sustentacular cells and (2) brushlike projections, termed epidermal brushes, that represent specialized epidermal cells containing keratin. Both of these structures were studied with the combined use of light microscopy and scanning and transmission electron microscopy. The general body surface, fins, and rostral cutaneous processes of some loricariid catfishes are covered with taste or terminal buds but lack the epidermal brushes. It is suggested that the epidermal brushes found on the oral papillae serve as protective devices for the taste buds and as abrasive surfaces for substrate scraping during feeding. The taste buds on the oral papillae may detect any gustatory stimuli from the resulting substrate disturbance. Comparative studies reveal many differences in the number and spatial arrangement of these two structures on the oral papillae among the several species of the Loricariidae examined. These differences may represent functional adaptations to the various modes of life in the Loricariidae.