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.