Bustos Domecq made his first appearance as F. Bustos, the pseudonym under which Borges, in 1933, published his first fictional story, now known as "El hombre de la Esquina Rosada", but originally titled "Hombre de las orillas" ("Man from the Slums").
He changed his first initial and acquired a "segundo apellido" (basically, a mother's maiden name) as Borges and Bioy Casares later used the psuedonym "H. Bustos Domecq" for some of their lighter works. (It may or may not be relevant that in the Spanish language, "f" and "h" are, at times, orthographically interchangeable, as in "fidalgo" and "hidalgo.")
H. Bustos Domecq was the original credited author of the parodic detective stories in Seis problemas para don Isidro Parodi, 1942 (translated 1981 as Six Problems for Don Isidro Parodi), the overblown essays of Crónicas de Bustos Domecq, 1967, (translated 1976 as Chronicles of Bustos Domecq), and Nuevos Cuentos de Bustos Domecq, (1972? Borges, a Reader says 1977).