bibtex-dialect-list is a variable defined in `bibtex.el'.
Its value is
(BibTeX biblatex)

List of BibTeX dialects known to BibTeX mode.
For each DIALECT (a symbol) a variable bibtex-DIALECT-entry-alist defines
the allowed entries and bibtex-DIALECT-field-alist defines known field types.
Predefined dialects include BibTeX and biblatex.

You can customize this variable.

This variable was introduced, or its default value was changed, in version 24.1 of Emacs.