Record of uncommon body coloration in the filefish Thamnaconus modestus (Monacanthidae) from the Pacific coast of Chiba Prefecture

A single specimen of Thamnaconus with uncommon body coloration, collected from the Pacific coast of Chiba Prefecture, central Japan, was donated to Kindai University by a recreational fisherman. This specimen has similar coloration to T. modestoides (Barnard, 1927), and its external morphology corresponds with that of T. modestus (Günther, 1877). Species identification of the specimen was confirmed by observation of external morphology and molecular analysis using mitochondrial COI gene and nuclear RAG1 gene. Based on the results, the specimen was identified as T. modestus, not T. modestoides or a hybrid individual of these species.