Clarinets other than the standard B♭ and A clarinets are sometimes known as harmony clarinets. However, there are many differently-pitched clarinet types, some of which are very rare. They may be grouped into sub-families, but grouping and terminology vary; the list below reflects popular usage and compares it with systems advocated by a few influential authors. See separate articles for additional details.
Piccolo clarinet — Very rare. Also known as octave clarinet or Bb sopranino clarinet. Pitched an octave higher than the B♭ clarinet.
A♭ piccolo clarinet.
Rendall uses the term octave clarinet and includes also obsolete instruments in C, B♭, and G.F. Geoffrey Rendall. The Clarinet. Third Edition. London: Ernest Benn Limited, 1971, pp. 3-4.
Shackleton lists also obsolete instruments in C, B♭, and A.Nicholas Shackleton. "Clarinet", Grove Music Online, ed. L. Macy (accessed 21 February 2006), (subscription access).