Studies on Lejeuneaceae, II. Rectolejeunea Evs. emend. Schust. (Lejeuneoideae)

dRectolejeunea includes an ensemble of Lejeunea-like taxa which, in the fie ld have a distinctive aspect: all taxa are very Aat plants, growing closely applied to the substrate (usually bark, less often living leaves, rarely r ocks). Aspect alone will usually allow field recognition and aspect usually allows separation of Rectolejeunea from the allied genus Lejeunea. It is a complex, diversified genus similar to Cheilolejeunea, from which it was se gregated by Evans (1906), in including mostly taxa that have a lejeuneoid i nnovation (subg. Heterolejeunea, Chaetolejeunea, Notholejeunea); one subgen us (Rectolejeunea) has a pycnolejeuneoid innovation; a fifth subgenus, Invi solejeunea, is not known with gynoecia and its phylogenetic position remain s controversial. Two subgenera (Heterolejeunea, Chaetolejeunea) include tax a lacking ocelli and which have oil-bodies in all leaf cells; three subgene ra (Invisolejeunea, Notholejelmea, Rectolejeunea) include taxa that bear ba sal ocelli (Invisolejeunea) or basal + laminar ocelli (Rectolejeunea, Notho lejeunea). Subg. Notholejeunea and Rectolejeunea have small or vestigial or no oil-bodies in laminar cells; subg. Chaetolejeunea, Heterolejeunea and I nvisolejeunea have conspicuous oil-bodies of chlorophyllose laminar cells. If laminar ocelli occur, these are about the same size as the adjacent chlo rophyllose cells, except in Notholejeunea, where they are mostly much large r than adjacent chlorophyllose cells. The genus probably includes under 20 species; it is largely Afro-American b ut the isolated R. (Notholejeunea) ocellata is a rare endemic of New Zealan d. An isolated species of subg. Heteroleje unea (R. denudata sp. n.) also o ccurs in New Zealand. One species of subg. Rectolejeunea (R, monoica) is described from Brazil; t hree species of subg. Heteuolejeunea are described, one (R. colombiana) fro m Colombia, one (R. pachyderma) from Venezuela. The last fits only precario usly in Rectolejeunea: it is a soft-textured, fragile plant which-unlike ot her taxa of the genus-readily blackens when drying.