Rubigula is a genus of Asian passerine birds in the bulbul family, Pycnonotidae.
The name combines the Medieval Latin rubinus meaning "ruby" with Latin gula meaning "throat".
1/ The black-capped bulbul, or black-headed yellow bulbul (Chào mào vàng chóp đen, Rubigula melanictera) is a member of the bulbul family of passerine birds.
The black-capped bulbul was formerly placed in the genus Pycnonotus. Black-capped bulbul has upper half of the head black and lower half yellow, while the black-headed bulbul (Brachypodius melanocephalos) has the whole head black. Both are crestless.

2/ Black-crested bulbul (Rubigula flaviventris, Chào mào vàng mào đen)
flaviventris: New Latin; from flāvus (“yellow”) +‎ venter (“belly”)