Comparative Morphology and Morphometry of the Olfactory Organ in the Five Korean Torrent Catfishes, Genus Liobagrus, with a Taxonomic View

The morphology and morphometry of the olfactory organ of Korean torrent catfishes, genus Liobagrus, consisting of only five endemic species, were investigated by stereo microscopy, scanning electron microscopy, and statistical analysis. They showed the same morphological structure, externally and internally, including a tubular anterior nostril, a slit posterior nostril, and a rosette structure with several linguiform lamellae. Interestingly, however, the lamellar number (LN) revealed specific characteristics useful to identify the five species anatomically: 16-19 in Liobagrus andersoni (with standard length, SL, 96.8 ± 5.5 mm, mean ± SD), 14-16 in Liobagrus obesus (86.9 ± 13.4 mm), 22-27 in Liobagrus mediadiposalis (99.8 ± 14.7 mm), 19-24 in Liobagrus somjinensis (90.1 ± 6.7 mm), and 14-18 in Liobagrus hyeongsanensis (74.0 ± 6.7 mm). Regarding SL, that of L. andersoni was longer than those of L. somjinensis and L. hyeongsanensis. As opposed to the SL, the LN to SL ratios of L. somjinensis (24.1 ± 2.1%) and L. hyeongsanensis (21.1 ± 1.4%) were greater than that of L. andersoni (18 ± 1.2%). These differences might be considered to reflect an interspecific morphological adaptation to micro-habitat according to olfactory importance and can be used as a taxonomic characteristic for this genus.