Field collections in the Southern Gulf of Oman and the Northwestern Arabian Sea, and examination of museum collections from this study area, yielded 7 genera and 33 species of apogonid fishes. Twenty one species of Apogon, one Archamia, four Cheilodipterus, three Fowleria, one Rhabdamia, two Siphamia, and one Holapogon are reviewed and illustrated. The Dhofar Cardinalfish, Apogon dhofar, nov. sp. is described from 21 specimens collected in the Arabian Sea, off southern Oman. It differs from the very similar A. pseudotaeniatus Gon, 1986 in its higher gill-raker count (12-17 developed rakers vs. 9- 11) and coloration. Apogon dhofar has narrower dark vertical bars (one scale row or less wide vs. two or more for A. pseudotaeniatus) which are often indistinct or absent in life and tend to fade with size; and a caudal spot which is much smaller (2-3% SL vs. 4-6% SL for pseudotaeniatus) and often absent in life. Both A. dhofar and A. pseudotaeniatus have small dark chromatophores covering their bodies, but A. dhofar differs in having these chromatophores concentrated under the posterior edge of each scale producing a reticulate pattern on the body. The Cryptic Cardinalfish, Apogon species C., is described from 19 specimens collected in the Gulf of Oman and Arabian Gulf It differs from the similar A. taeniatus Ehrenberg, 1828 in its lower gill-raker count (8 developed rakers vs. 10-15) and horizontal stripes (7-8 dark stripes vs. 5-6 indistinct stripes). Apogon species C. also has 3-4 short brown stripes radiating away from the eye whereas A. taeniatus occasionally has one narrow dark stripe. Apogon species C. lacks any caudal spot which is usually present in A. taeniatus. Apogon thurstoni Day, 1888 is shown to be a junior synonym of Apogon nigripinnis Cuvier, 1828, and Apogon smithvanizi Allen and Randall, 1994 is shown to be a junior synonym of Apogon gularis Fraser and Lachner, 1986. Apogon pharaonis Bellotti, 1874, formerly considered a junior synonym of Apogon nigripinnis Cuvier, 1828, is shown to be a valid species occurring in the Red Sea and western Indian Ocean, and the range of A. nigripinnis is redefined as eastern Indian to western Pacific. Apogon suezi Sauvage, 1883 is shown to be a junior synonym of A. pharaonis. A review is presented of the systematic literature of the apogonid fishes from the study area, and a key to genera and species is provided. Included in the key are 33 apogonid species known from the area and an additional 7 species (and one genus) not yet recorded but likely to occur.

Field collections in the Southern Gulf of Oman and the Northwestern Arabian Sea, and examination of museum collections from this study area, yielded 7 genera and 33 species of apogonid fishes. Twenty one species of Apogon, one Archamia, four Cheilodipterus, three Fowleria, one Rhabdamia, two Siphami...