Rozendaal showed that ussheri cannot be conspecific with venusta (Graceful Pitta), with which it was formerly combined.  Lacking further data he considered it, at least temporarily, a subspecies of granatina.

Lambert & Woodcock, in Pittas, Broadbills and Asities, subsequently treated ussheri as specifically distinct from granatina (Garnet Pitta).  Their reasons are (1) parapatric distributions, and (2) hardly any evidence of hybridisation.

Black-headed Pitta     Pitta ussheri
Gould  1877
ne Indonesia: n Borneo lowlands
split from: Pitta venusta
insert after: Pitta granatina
Frank Rozendaal,
Species limits within Garnet Pitta-complex
Dutch Birding 16, 6 (1994): 239-245