Lejeunea (sect. Heterolejeunea) G. E. Lee & Gradst., comb. et stat. nov.

[Clade VII]Lejeunea sect. Heterolejeunea(R. M. Schust.) G. E. Lee & Gradst. comb. et stat. nov. Rectolejeunea subg. Heterolejeunea R. M. Schust. (Schuster 1955: 122) Dicladolejeunea R. M. Schust. (Schuster 1962: 68) – Type species: D. anomala R. M. Schust. (= L. rotundifolia Mitt.). Lejeunea subg. Chaetolejeunea (R. M. Schust.) R. M. Schust. (Schuster 1962: 68) – Type species: L. setacea Steph. Stylolejeunea Sim (Sim 1926: 67) – Type species: S. duncaniae Sim (= L. duncaniae (Sim) M. E. Reiner). Type species Lejeunea phyllobola Nees & Mont. Description Plants dull green, rarely glossy. Vegetative branches Lejeunea - type, occasionally Radula - type. Stem epidermis cells ca 2–3 times larger than medullary cells, rarely strongly inflated; medullary cell rows few, usually 4–7. Leaf cells with small trigones, with or without intermediate cell wall thickenings. Lobules sometimes with a very long tooth. Oil bodies granular, 2–10 per cell, colourless, relatively large, up to 20 µm long and sometimes fill the entire cell lumen. Male bracteoles restricted to the base of the male spike or present throughout. Gynoecial innovations usually fertile. Perianths often compressed, with 5 smooth keels. Asexual reproduction common, by strap-shaped gemmae, caducous leaves and branches. Distribution Afro-American. Species Lejeunea deplanata Nees, L. kuerschneriana Pócs, L. oligoclada Spruce, L. parviloba Ångstr. (= L. tapajosensis Spruce), L. phyllobola Nees & Mont., L. ptosimophylla C. Massal., L. rotundifolia Mitt., L. ruthii (A. Evans) R. M. Schust., L. subplana (Steph.) C. J. Bastos, L. trinitensis Lindenb. Further species (not sequenced) Lejeunea duncaniae, L. evansiana (R. M. Schust.) Schäf. - Verw., L. rionegrensis Spruce, L. setacea, L. spiniloba Lindenb. & Gottsche. Notes Characteristic of sect. Heterolejeunea are the rather dull green, dioicous plants with ± compressed perianths and frequent occurrence of vegetative reproduction. The position of L. rotundifolia in the section is somewhat unexpected, standing out by its large size with stems to 8 cm long and made up of 11–18 rows of epidermal cells and 22–55 rows of medullary cells, with 4–6 cells wide ventral merophytes. Previously, the species was placed in a separate genus, Dicladolejeunea. Interestingly, L. rotundifolia occasionally produces vegetative branches of the Radula - type. The latter character is very rare in Lejeunea and is otherwise seen in L. deplanata and L. phyllobola, both in the same section. References Schuster (1980), Reiner-Drehwald (2005 b, 2010 a), Bastos and Gradstein (2020).