Morphometric Variation in Lepidogrammus cumingi and Dasylophus superciliosus from Greater Luzon, Philippines based on Museum Specimens

The monotypic Scale-feathered Malkoha Lepidogrammus cumingi (Fraser 1839) and polytypic Red-crested Malkoha Dasylophus superciliosus (Dumont 1823) are two of the endemic cuckoos in the Philippines. The taxonomy and distribution of these endemic cuckoos are poorly known. Recent distribution data of these cuckoos showed broader distribution patterns in the islands of Luzon, Catanduanes, and Marinduque; however, morphometric variations among these island populations are still unknown. While both species are sexually monomorphic, the differences between sexes were mainly based on plumage coloration. Dasylophus superciliosus is composed of two subspecies: ssp. superciliosus (Southern Luzon) and ssp. cagayanensis (Northern Luzon). The separation of the two subspecies of D. superciliosus was determined by the differences in superciliary feather, the coloration of breast plumage, and the tail band. In this study, we investigated the morphometric variations (1) between subspecies of D. superciliosus, (2) among island populations, and (3) between sexes (sexual dimorphism) of the two malkoha species. Four linear measurements (bill length, wing length, tarsus length, and tail length) were measured from 184 museum specimens. Results showed that the Catanduanes group (n=10) of L. cumingi exhibited a smaller body size than the Marinduque group (n=9). Red-crested Malkoha D. superciliosus showed significant differences between its two subspecies where the ssp. cagayanensis (n=28) exhibited smaller body size (bill length, wing length, and tail length) compared to ssp. superciliosus (n=81). Lastly, this study confirms that the two malkoha species are sexually monomorphic based on the analyzed morphometric data.