A small thalloid plant Mstikhinia duranteae
gen. et sp. nov. from the Lower Carboniferous deposits of the Moscow Coal Basin
is described. The most remarkable feature of Mstikhinia is the numerous
pores. These pores are variable in size and shape, ranging from simple circular
holes to structures similar to immersed stomata with guard-cells. We consider
these pores served for mucilage release and probably are not homologous to
stomata of tracheophytes. On the whole, Mstikhinia combines the
characters of several plant divisions, e.g. Anthocerotae, Hepaticae,
Pteridophyta (gametophytes), but it cannot be attributed to any of them. For
such combined forms, Meyen (1987) introduced the concept of “synthetic type”. It
seems probable that Mstikhinia belongs to one of such ancient
“synthetic” groups, not recognized yet.