Calornis pacificus Finsch (part), Journ. Mus. Godeffroy, 12, 1876, pp. 17, 32 (Palau); idem (part), Journ. f. Ornith., 1880, p. 289 (Palau); idem (part), Proc. Zool. Soc. London, 1880, p. 576 (Palau); idem (part). Ibis, 1881, p. 111 (Pelew).
Aplonis kittlitzi Wiglesworth (part), Abhandl. und Ber. Zool. Mus. Dresden, no. 6, 1890-1891 (1891), p. 44 (Pelew); Oustalet (part), Nouv. Arch. Mus. Hist. Nat. Paris, (3), 7, 1895, p. 212 (Palaos); Hartert (part), Novit. Zool., 5, 1898, p. 58 (Pelew); Matschie (part), Journ. f. Ornith., 1901, p. 112 (Palau); Takatsukasa and Kuroda (part), Tori, 1, 1915, p. 55 (Pelew).
Aplonis opaca subsp nov.? Momiyama, Birds Micronesia, 1922, p. 13 (Pelew); Kuroda, in Momiyama, Birds Micronesia, 1922, p. 72 (Pelew).
Aplornis opaca orii Hand-list Japanese Birds, 3d ed., 1942, p. 188 (Babelthuap, Koror, Peliliu, Anguar).
Aplonis opaca orii Hand-list Japanese Birds, rev., 1932, p. 169 (Palau); Yamashina, Tori, 10, 1940, p. 673 (Palau).
Aplonis opacus orii Mayr, Birds Southwest Pacific, 1945, p. 297 (Palau); Baker, Smithson. Misc. Coll., vol. 107, no. 15, 1948, p. 71 (Peleliu, Ngesebus, Garakayo).
Geographic range.—Micronesia: Palau Islands—Kayangel, Babelthuap, Koror, Garakayo, Ngesebus, Peleliu, Ngabad, Angaur.
Characters.—Adult: Resembles adult of A. o. opacus, but slightly larger with bill longer and shallower, and feathers with distinct greenish gloss both on the upper parts and the lower parts. Resembles A. o. angus in the amount of greenish gloss on feathers, but bill shallower. Depth of bill of A. o. opacus measures, on the average, 9.5 for males and 9.0 for females; of A. o. angus 8.5 for both males and females; of A. o. orii 7.5 for both males and females.
Immature: Resembles immature of A. o. angus, but streaking on underparts duller.