Abstract
A new freshwater species with two new subspecies of the gobiid fish genus Rhinogobius is described from the Yaeyama Group of the Ryukyu Islands, Japan. One of the subspecies, Rhinogobius aonumai aonumai (29 specimens, 35.9–70.5 mm SL) known only from Iriomote-jima Island, is distinguished from all congeneric species-group taxa (species and subspecies) by having the following combination of features: 9–15 predorsal scales; 32–37 longitudinal scales; 11+15–17=26–28 vertebrae (mode 27); anteriormost two pterygiophores (proximal radials) of the second dorsal fin mounted over the neural spine of 10th vertebra; fifth segmented pelvic-fin ray divided into 3–4 (usually four) branches at the position where proximal-most segment of each branch alignes transversely; yellow-colored body in freshly-collected; no dark spot on first dorsal fin; caudal fin with vertical rows of dark spots or forming dark zigzag bands. The other subspecies, Rhinogobius aonumai ishigakiensis (12 specimens, 33.3–56.5 mm SL) known only from Ishigaki-jima Island, is distinguished from all congeneric species-group taxa by having the following combination of features: 10–14 predorsal scales; 33–38 longitudinal scales; 10+16–18=26–28 vertebrae (mode 27); anteriormost two pterygiophores (proximal radials) of the second dorsal fin mounted over the neural spine of 9th vertebra; fifth segmented pelvicfin ray divided into 2–3 (usually two) branches at the position where the proximal-most segment of each branch alignes transversely; yellow-colored body in freshly-collected; no dark spot on first dorsal fin; caudal fin with dark zigzag bands on the caudal fin.
