Adult Male:
The forehead, crown, nape, and upper neck exhibit a steel-blue iridescence with a reddish tinge. The sides of the head are dull black. The sides of the neck, back, and shortest scapular feathers are dull red. The lesser wing coverts, longest scapular feathers, and a band adjacent to the red area on the back are black. This is followed by a yellow band. The remaining parts of the flanks, upper tail coverts, and three-quarters of the base of the central tail feathers are steel-blue.
The remaining part of the tail, the median and greater wing coverts, and the flight feathers are dull brownish-black. The outer tail feathers have white tips. The chin is black. The throat is blue with a reddish iridescence. The upper breast is black, with red tips on the feathers of the sides of the breast. The remaining part of the abdomen is pale yellow, with a pale grayish tinge in the middle of the abdomen, and the breast has a deep red stripe. The underwings and axillaries are pale yellowish-white.
Adult Female:
The upper back is yellowish-greenish-gray, with dark stripes down the middle of the feathers on the crown. The flanks are pale yellow. The abdomen is grayish-green, with a slightly lighter color on the belly. The tail is dull black with pale feather tips, except for the central pair. The underwings and axillaries are pale white.
Differences from Aethopyga siparaja Female:
The female of this species differs from the female of Aethopyga siparaja in the following aspects: pale yellow flanks, yellow undertail coverts, a slightly grayer chin and throat. Eyes are dark brown or reddish-brown. Beak is black. Legs are dark brown or black.
Measurements:
Wing: 42 – 56 mm; tail: 63 – 69 mm; tarsus: 14 – 15 mm; beak: 18 – 20 mm.
Distribution:
This sunbird subspecies is distributed in Myanmar, Thailand, Southwestern China (Yunnan), and Indochina. Specimens have been collected in Vietnam from Lào Cai, Cao Bằng (Bảo Lạc), and Lâm Đồng provinces.