Megazosterops palauensis Stresemann, Ornith. Monatsber., 38, 1930, p. 159 (Baobeltaob); Snouckaert, Alauda (2), 3, 1931, p. 26 (Palau); Stresemann, Mitt. Zool. Mus. Berlin, 17, 1931, p. 235 (Baobel Taob = Babelthuap); Mathews, Ibis, 1931, p. 48 (Palau); Hand-list Japanese Birds, rev., 1932, p. 172 (Palau); Yamashina, Tori, 10, 1940, p. 674 (Palau); Hand-list Japanese Birds, 3d ed., 1942, p. 191 (Babelthuap, Peleliu).
Rukia palauensis Mayr, Amer. Novit., no. 1269, 1944, p. 7 (Palau); idem, Birds Southwest Pacific, 1945, pp. 294, 300 (Peliliu); Baker, Smithson. Misc. Coll., vol. 107, no. 15, 1948, pp. 67, 74 (Peleliu).
Geographic range.—Micronesia: Palau Islands-Babelthuap, Peleliu.
Characters.—Adult: A large white-eye with upper parts near "Saccardo's olive" (some individuals darker brown), head and neck more olivacious, rump browner; auriculars blackish with pale yellow streaks; narrow supra-orbital stripe pale olive; orbital ring indistinct; underparts near "olive lake," chin lighter, under tail-coverts light yellowish-brown; wing and tail feathers dark brown, except for tawny outer edges and whitish inner edges; maxilla horn-color; mandible yellowish to tawny; feet tawny; iris grayish-brown.
Measurements.—Measurements of Rukia are listed in [table 52]. Measurements of males and females are comparable within the same species.
Table 52. Measurements of Rukia
Table 52. Measurements of Rukia
| Species | No. | Wing | Tail | Culmen | Tarsus |
| R. palauensis | 19 | 80 | 54 | 21.5 | 25 |
| (76-84) | (51-57) | (20.0-22.5) | (24-26) | ||
| R. ruki | 8 | 81 | 52 | 21.5 | 23 |
| (76-85) | (51-52) | (20.0-23.0) | (22-24) | ||
| R. sanfordi | 18 | 70 | 44 | 23.0 | 21 |
| (67-71) | (41-47) | (22.0-24.0) | (20-22) |
Specimens examined.—Total number, 21 (12 males, 9 females), as follows: Palau Islands, USNM—Peleliu, 11 (Aug. 27, 29, 30, Sept. 4, 5, 6, 7, Dec. 4, 5); AMNH—Peleliu?, 10 (Dec.).
Molt.—Specimens taken in August and September are in worn plumage, a few individuals show evidence of molt. Specimens taken in December are in fresh plumage, although two or three individuals are in the final stages of molt. This places the period of molt as September, October, and November. Nesting evidently occurs in the summer; one male taken on August 27, 1945, had enlarged gonads.