Ruellia shaferiana, a seldom collected and incompletely known species, is described in detail and compared with two vegetatively similar Cuban endemics, Dyschoriste bayatensis and the recently described Hygrophila urquiolae, and with the two Cuban species of Apassalus (A. cubensis and A. parvulus). All are placed by Scotland and Vollesen, in their classification of Acanthaceae, in the newly circumscribed subtribe Ruelliinae. Contrary to Dyschoriste, the other taxa studied have anther thecae that lack basal awns. Absence of these awns is the single character distinguishing Apassalus from Dyschoriste, and it has been suggested that both be combined. Our results lend support to that suggestion and prompt the transfer of A. parvulus to Dyschoriste. Study of pollen by SEM confirms the generic placement of the species studied, again associating Apassalus with Dyschoriste. Seed indumentum was studied by LM and REM, complementing earlier studies of the remarkable hygroscopic mucilaginous hairs, which apparently characterise the subtribe. Hygrochastic capsule dehiscence was detected in all four species. Pre-dawn anthesis and flowers withering by noon were observed in R. shaferiana. H. urquiolae, only known from a small area in W Cuba, is newly reported from E Cuba, and conversely, W Cuban occurrences of R. shaferiana are put on record. For three of the names lectotypes are designated, as Urban's original material was destroyed in Berlin in World War II.