A genre that is "out of sight" to "outsiders and apprentices"; occluded genres perform "essential waystage roles in the administrative and evaluative functioning of the research worlds" (Swales, 2004, p. 18). Swales originated the term and uses it specifically with reference to the genre system of academic research.
Swales, J. M. (2004). Research genres: Explorations and applications. Cambridge, UK ; New York: Cambridge University Press.
Swales, J. M. (2009). Worlds of genre—metaphors of genre. In C. Bazerman, A. Bonini & D. Figueiredo (Eds.), Genre in a changing world (pp. 3–16). Fort Collins, CO: WAC Clearinghouse and Parlor Press.
Although originally developed to describe academic discourse, the concept of "occluded genres" has been recently used outside of the study of academic/research genres in Shapero (2011), where it's been applied to suicide notes.
Swales, J. (1996). Occluded genres in the academy: The case of the submission letter. In E. Ventola & A. Mauranen (Eds.), Academic writing: Intercultural and textual issues. Amsterdam: John Benjamins. This is the first instance of the term; Swales uses it here specifically with reference to the genre chain necessary to publish an academic research article.
Dylan Dryer, Carolyn Miller, Natasha Artemeva