The Retention of the Lateral-Line Nucleus in Adult Anurans

The presence or absence of the primary lateral-line nucleus of the rhombencephalic alar plate was examined in adult frogs with an extensive aquatic life style or a systematic affinity to species known to retain the lateral-line system after metamorphosis. Clearcut indications for the presence of a lateral-line nucleus and lateral-line nerves were obtained for Lepidobatrachus laevis, Ooeidozyga laevis and O. lima. In L. laevis and O. lima we found lateral-line neuromasts in the skin. No lateral-line nerves, but an indication of the presence of a small lateral-line nucleus was found in adult O. baluensis, Telmatobius hauthali schreiteri, Conraua crassipes and Ascaphus truei. No lateral-line nerves or nuclei were present in Rhinophrynus dorsalis, Pseudis paradoxa and Lysapsus limellus. These data indicate that in four out of six superfamilies either the neuromasts in the skin and/or the lateral-line nucleus are retained in some adult frogs with an aquatic life style. However, within each superfamily, species with a purely terrestrial life style do not retain their lateral-line system after metamorphosis.