Comment:Note: Hudstedt had to rename a fossil from Java that he had named Achnanthes similis Hustedt non McCall in 1939 and chose the name A. simplex.
A. simplex (Perag.) E.J.F.Wood (1963 CSIRO Div Fish & Oceanogr. Report 36 p. 7 ) is a latter homonym.
APC Comment:R.Cowan (2008) uses this taxon concept.