Taste buds on the external body surface and oropharyngeal cavity in Glyptosternon maculatum (Regan, 1905)

Summary The aim of the study was to determine the distribution and relative frequency of Glyptosternon maculatum taste buds (TB) using paraffin sectioning, the HE staining method and light microscopy. TBs were found on a variety of surface body areas (lips, barbels, lateral, ventral and dorsal areas, and the dorsal, pelvic, pectoral, anal and adipose fins), as well as in the oropharyngeal cavity. In the epithelium of histological figures of sampled body parts, TB was pear-shaped from the bottom to the top. The ratio of height/width value of the taste bud was above 1.0, with a range from 1.2 to 2.0. Highest TB frequencies were in the mandibular outer barbel (18.5 ± 3.7 mm−2), mandibular inner barbel (17.1 ± 5.4 mm−2), nasal barbel (16.8 ± 4.2 mm−2) and maxillar barbel (15.9 ± 2.7 mm−2), lips (14.6 ± 3.6 mm−2) and oropharyngeal cavity (13.2 ± 3.5 mm−2). TBs occurred in moderate quantities on the forehead (6.9 ± 2.1 mm−2), anal fin (5.8 ± 2.3 mm−2), and La2 (3.9 ± 1.6 mm−2, between pelvic and anal fins), then decreased to a few in the La1 area (3.4 ± 1.3 mm−2), operculum (2.5 ± 1.3 mm−2) and other examined areas. Type I (elevated), type II (slightly elevated) and type III (not elevated or sunken) TBs were found in the epithelium of various sampling locations. These are the first descriptions of taste buds in G. maculatum.