This article illustrates Gymnocodium (G. devonicum nov. sp.) observed
in Middle Devonian carbonates of the Dinant Synclinorium. Gymnocodiace
ans were considered up to now as ubiquitous and very abundant calcifie
d Late Permian-Mesozoic algae. The equivalent of the ''Gymnocodiaceae
community'' is observed here in an Eifelian (''Couvinian'', Couvin Lim
estone) carbonate ramp, quite a radical change of the known stratigrap
hy.