Lejeunea (sect. Lamacerinae) R. M. Schust.

[Clade III]Lejeunea sect. LamacerinaeR. M. Schust. (Schuster 1980: 967) Dactylolejeunea R. M. Schust. (Schuster 1970: 341) – Type species: D. acanthifolia R. M. Schust. (= L. paucidentata (Steph.) Grolle). Type species Lejeunea lamacerina (Steph.) Schiffn. Description Plants autoicous, delicate, usually less than 1 mm wide. Stem epidermis cells ca 2 times or less larger than medullary cells, not strongly bulging outwards, medullary cells in 4–20 rows. Cuticle smooth, rarely punctate-papillose. Oil bodies finely to coarsely granular, 3–10 per cell, relatively large. Gynoecial innovations sterile (rarely fertile). Perianths usually 5 - keeled, keels frequently 2 - winged and crenate (by mammillose cells) to toothed, dentate-ciliate. Asexual reproduction by specialized devices usually absent (by ribbon-like gemmae in L. pulchriflora). Distribution Tropical America, Europe, and eastern North America; one species, L. pulchriflora, in the Paleotropics. Species Lejeunea bermudiana (A. Evans) R. M. Schust., L. corynantha Spruce, L. cristulata (Steph.) M. E. Reiner & Goda, L. grossitexta (Steph.) M. E. Reiner & Goda, L. intricata Prantl, L. laeta (Lehm. & Lindenb.) Lehm. & Lindenb., L. lamacerina (Steph.) Schiffn., L. paucidentata (Steph.) Grolle, L. pulchriflora (Pearson) G. E. Lee, Bechteler, Pócs, Schäf. - Verw. & Heinrichs, L. sporadica Besch. & Spruce, L. urbanii (Steph.) Steph. Further species (not sequenced) Lejeunea patens Lindb. Notes Typical of sect. Lamacerinae are the delicate, autoicous plants with crenate to dentate-ciliate, 2 - winged perianth keels, a usually smooth cuticle (finely punctate-papillose only in L. intricata and L. pulchriflora), granular oil bodies, and sterile innovations. Lejeunea corynantha deviates by its eplicate perianth but otherwise fits the section well morphologically. The European L. patens is placed in this section based on its granular oil bodies and its close similarity to L. lamacerina. Section Lamacerinae is morphologically very similar to sect. Microlobae (subg. Crossotolejeunea), but the perianths in the latter section are not 2 - winged. References Schuster (1980), Paton (1999), Reiner-Drehwald and Goda (2000), Reiner-Drehwald and Schäfer-Verwimp (2008), Lee et al. (2016), Bastos and Gradstein (2020).