Aplonis opaca guami Kuroda, in Momiyama, Birds Micronesia, 1922, p. 71 (Guam); Mathews, Syst. Avium Australasianarum, 2, 1930, p. 847 (Guam); Yamashina, Tori, 7, 1932, p. 394 (Saipan, Rota); Hand-list Japanese Birds, rev., 1932, p. 169 (Guam, Rota, Tinian, Saipan).
Aplonis opaca harterti Momiyama (part), Birds Micronesia, 1922, p. 10 (Type locality, Saipan); Kuroda (part), in Momiyama, Birds Micronesia, 1922, p. 71 (Saipan); Mathews, Syst. Avium Australasianarum, 2, 1930, p. 847 (Saipan).
Aplornis opaca harterti Takatsukasa and Yamashina, Dobutsu. Zasshi, 43, 1931, p. 487 (Saipan).
Aplornis opaca guami Takatsukasa and Yamashina, Dobutsu. Zasshi, 44, 1932, p. 221 (Tinian, Rota); Hand-list Japanese Birds, 3d ed., 1942, p. 188 (Saipan, Tinian, Rota, Guam).
Aplonis opacus guami Mayr, Birds Southwest Pacific, 1945, p. 297 (Guam, Rota, Tinian, Saipan); Watson, The Raven, 17, 1946, p. 41 (Guam); Downs, Trans. Kansas Acad. Sci., 49, 1946, p. 103 (Tinian); Stott, Auk, 1947, p. 527 (Saipan, Guam); Baker, Smithson. Misc. Coll., vol. 107, no. 15, 1948, p. 69 (Guam, Rota, Tinian, Saipan).
Aplonis opacus Wharton, Ecol. Monogr., 16, 1946, p. 174 (Guam); Strophlet, Auk, 1946, p. 540 (Guam); Baker, Condor, 49, 1947, p. 125 (Guam).
Geographic range.—Micronesia: Mariana Islands—Guam, Rota, Tinian, Saipan.
Characters.—Adult: Resembles closely A. o. angus in the amount of greenish gloss present on the body feathers, but with slightly shorter and deeper bill.
Immature: Resembles the immature of A. o. angus but streaks on underparts brighter and less-dingy yellow.
Measurements.—Measurements are listed in [table 45]. The writer (1948:69) has given average measurements for the length of wing of adult males from Guam as 127, from Rota as 122, from Tinian as 131, and from Saipan as 131; for depth of bill of adult males from Guam as 9.0, from Rota as 9.0, from Tinian as 9.5, and from Saipan as 10.0.