Acrocephalus syrinx Hartert (part), Novit. Zool., 5, 1898, p. 58 (Pagan); Seale (part), Occ. Papers Bernice P. Bishop Mus., 1, 1901, p. 53 (Pagan).
Acrocephalus stentoreus syrinx Kuroda (part), in Momiyama, Birds Micronesia, 1922, p. 67 (Pagan).
Conopoderas yamashinae, Hand-list Japanese Birds, rev., 1932, p. 177 (Pagan).
Conopoderas luscinia yamashinae Hand-list Japanese Birds, 3d ed., 1942, p. 196 (Pagan).
Acrocephalus luscinia yamashinae Mayr, Birds Southwest Pacific, 1945, p. 294 (Pagan).
Geographic range.—Micronesia: Mariana Islands—Pagan.
Characters.—Resembles A. l. syrinx, but duller and more brownish and less olive-rufous on back, rump and tail; bill shorter and more curved.
Takatsukasa (1931:485) gives the following description: "Upperparts dark olive brown, paler on the lower rump; remiges and rectrices dark olive-brown, margined with brown. Superciliary stripe distinct and buff; chin, throat, breast and abdomen pale brown; ear-coverts, sides of neck, sides of breast and flanks dusty greyish brown, belly and under tail-coverts pale buff. Bill clove brown, legs grey, and iris Van Dyke brown." He continues, "It differs from Conopoderas syrinx of Caroline Islands by its colouration and the shape of the bill, namely in the new form the culmen is more curved and more stout, and the tail is less roundish and nearly square."
Measurements.—Takatsukasa and Yamashina (1931b:485) lists the following measurements: 13 adult males—wing, 75-80; tail, 65-70; culmen, 20-22; 6 adult females—wing, 73-77; tail, 60-65; culmen, 20-22.