Lejeunea (sect. Lejeunea) Lib.

[Clade IV]Lejeunea sect. Lejeunea Lejeunea sect. Cladiophorae R. M. Schust. (Schuster 1980: 995) – Type species: L. cladiophora (R. M. Schust.) R. M. Schust. (= L. cancellata Nees & Mont.). ? Lejeunea subg. Pleurolejeunea R. M. Schust. (Schuster 1963: 123) – Type species: L. patagonica (Steph.) Steph. Amphilejeunea R. M. Schust. (Schuster 1978: 431) – Type species: A. viridissima R. M. Schust. (= L. catinulifera Spruce). Ciliolejeunea S. W. Arnell (Arnell 1953: 176) – Type species: C. capensis S. W. Arnell (= L. villaumei (Steph.) Grolle). Cladolejeunea Zwickel (Zwickel 1933: 112) – Type species: Ceratolejeunea aberrans Steph. (= L. gradsteiniana Pócs). Cryptogynolejeunea R. M. Schust. (Schuster 1994: 215) – Type species: C. reflexistipula (Lehm. & Lindenb.) R. M. Schust. (= L. reflexistipula (Lehm. & Lindenb.) Lehm. & Lindenb.). Oryzolejeunea (R. M. Schust.) R. M. Schust. (Schuster 1992: 249) – Type species: O. antillana (R. M. Schust.) R. M. Schust. (= L. herminieri (Steph.) R. L. Zhu). Lejeunea sect. Cavifoliae R. M. Schust. (Schuster 1957: 142), nom. inval. – Type species: same as for genus Lejeunea. Type species Lejeunea cavifolia (Ehrh.) Lindb. Description Plants mostly autoicous (occasionally dioicous), glossy green, slightly altered by drying. Stem epidermis cells ca 2–4 times larger than medullary cells, not strongly bulging outwards; medullary cells in 4–16 rows (exceptionally, in L. reflexistipula, epidermis cells strongly bulging outwards, ca 6 times larger than inner cells, and medullary cell rows more numerous, 19–40). Cuticle smooth or punctate-papillose, oil bodies homogeneous, ca 10–30 per cell. Underleaves bifid or undivided. Gynoecial innovations sterile or fertile, with up to two gynoecia in a row. Perianths equally 5 - keeled, keels usually long, extending to the lower half of the perianth, often winged or with appendices (horns, teeth, tuberculae). Asexual reproduction by specialized devices usually absent (by caducous branches in L. cancellata). Distribution Pantropical and extending into temperate regions of the Northern and Southern Hemisphere. Species Lejeunea alata Gottsche, L. amaniensis E. W. Jones, L. cancellata, L. caripensis Lindenb. & Gottsche (= L. cerina auct. non (Lehm. & Lindenb.) Lehm. & Lindenb.), L. catinulifera, L. cavifolia, L. drummondii Taylor, L. eckloniana Lindenb., L. geisslerae Pócs, L. helmsiana (Steph.) Steph., L. herminieri, L. holtii Spruce, L. japonica Mitt., L. obscura Mitt., L. oracola M. A. M. Renner, L. perichymidia M. A. M. Renner (= L. epiphylla Colenso), L. puiggariana Steph., L. reflexistipula, L. sharpii (R. M. Schust.) R. M. Schust., L. subsessilis Spruce (= L. monimiae (Steph.) Steph.), Lejeunea sp. 2. (= “ L. caracensis Lindenb. ”, Figs 5, 6). Further species (not sequenced) Lejeunea cyathearum E. W. Jones, L. gradsteiniana Pócs, L. villaumei (Steph.) Grolle. Notes The typical character of sect. Lejeunea, separating it from most other sections of Lejeunea, are the small, homogeneous, Massula - type oil bodies, ca 10–30 per cell. In other sections, oil bodies are usually granular, being built of very small to large granules, and less than 10 per cell. Further characters of sect. Lejeunea are the thin stems with only 4–12 medullary cell rows (exceptionally more cell rows in L. reflexistipula) and the occasional occurrence of two lobule teeth, with the first tooth being more than one cell long, and undivided underleaves (L. catinulifera, L. herminieri, L. reflexistipula). Lejeunea herminieri, type species of Oryzolejeunea, was not sequenced in this study and is placed in this section based on Ye et al. (2013) who sequenced it and found that the species was sister to L. catinulifera. Both have homogeneous oil bodies. Lejeunea holtii has long been considered a synonym of L. eckloniana (Söderström et al. 2002). However, the position of L. holtii on a long branch within the L. eckloniana species group and its distinctive morphology (Hodgetts et al. 2024), suggests that it may be a distinct taxon. The species is accepted here pending further work on its taxonomic status. Lejeunea cyathearum, L. gradsteiniana, and L. villaumei from Africa were not sequenced and are placed in sect. Lejeunea based on their homogeneous oil bodies and close similarity to L. eckloniana (Jones 1974). References Jones (1974), Schuster (1980), Wigginton (2004), Reiner-Drehwald (2005 a), Pócs (2010), Ye et al. (2013), Lee (2013), Renner et al. (2010, 2021), Gradstein (2021).