The genus
Xylothamia was first described in 1990 with nine species.
Molecular phylogenetic studies subsequently showed that these fell into two
clades. Four species, including the
type species of
Xylothamia, were most closely related to the then Caribbean genus
Gundlachia, and were transferred to that genus by
Lowell E. Urbatsch and
Roland P. Roberts in 2004. ,
Plants of the World Online accepted these transfers, treating
Xylothamia as a
synonym of
Gundlachia. •
Gundlachia corymbosa (Urb.) Britton ex Bold. (including
Gundlachia apiculata,
Gundlachia foliosa and
Gundlachia cubana) – Caribbean to
Venezuela •
Gundlachia diffusa (Benth.) Urbatsch & R.P.Roberts – northwest
Mexico •
Gundlachia domingensis (Spreng.) A.Gray (syns
Gundlachia floribunda,
Gundlachia lindeniana) –
Cuba,
Hispaniola •
Gundlachia triantha (S.F.Blake) Urbatsch & R.P.Roberts – southwest
Texas to northeast Mexico •
Gundlachia truncata (G.L.Nesom) Urbatsch & R.P.Roberts – Mexico (
Coahuila) ==References==