A taxonomic revision of the Naked-faced Spiderhunter Arachnothera clarae

The Naked-faced Spiderhunter Arachnothera clarae is endemic to the Philippines, traditionally in four subspecies: A. c. luzonensis on Luzon, A. c. philippinensis on Samar, Leyte and Biliran, A. c. malindangensis in western Mindanao and Basilan, and nominate A. c. clarae in eastern Mindanao. Descriptions of A. c. luzonensis have largely suggested a minor level of differentiation, but field experience with all taxa and inspection of specimens and photographs of live birds prompt a reconsideration of the evidence. Comparing adult males of A. c. luzonensis (n = 4), A. c. philippinensis (n = 11), A. c. clarae (n = 2) and A. c. malindangensis (n = 10) in five museums, plus a thorough review of online photographs of living birds, we find that A. [c.] luzonensis differs significantly in six morphological characters: bare bluish-grey lores (vs. mid-grey shading upwards to pinkish yellow in A. [c.] philippinensis, all blackish in A. c. clarae and A. c. malindangensis), a much shorter pale line along the commissure, softly grey-and-white-mottled (vs. slightly scaled olive-grey) underparts, bold pale upright bars on the median coverts, burnished chestnut (vs. olive-golden) fringes on the closed wing feathers, and a shorter bill. Moreover, A. [c.] philippinensis differs from A. c. clarae and A. c. malindangensis by the bare pinkish-yellow band extending from the lores over the forehead, paler loral colour, all-whitish (vs. sharply bicoloured) commissure line, and shorter tail. In strength and number these distinctions qualify A. [c.] luzonensis and A. [c.] philippinensis for species rank; and in the absence of any clear difference between specimens (including unmeasured females) A. c. malindangensis becomes a synonym of A. c. clarae.