Lejeunea (sect. Sordidae) Gradst. & G. E. Lee, sect. nov.

[Clade XII]Lejeunea sect. SordidaeGradst. & G. E. Lee sect. nov. Type species Lejeunea sordida (Nees) Nees. Description Plants dioicous, brown when dry. Stem epidermis cells distinctly larger than medullary cells, bulging outwards, medullary cells in 10–23 rows. Cuticle densely papillose. Lobules small, ovate-orbicular, strongly inflated, angle between keel and ventral leaf margin narrow, ca 90–120 °. Underleaves divided or undivided, large, reniform, ca 4–7 × stem width. Male bracteoles restricted to the base of the male spike. Gynoecia with sterile or fertile innovations. Perianths shortly 5 - keeled in the upper half, keels crenate by mammillose cells. Asexual reproduction by specialized devices absent (regeneration from leaf margins observed in L. sordida). Distribution Tropical amphi-Pacific. Species Lejeunea dipterota (Eifrig) G. E. Lee, L. leratii (Steph.) Mizut., L. mimula Hürl., L. sordida. Further species (not sequenced) Lejeunea anomala Lindenb. & Gottsche. Notes The typical characters of sect. Sordidae are the darkish brown plants (dried condition) with reniform underleaves, small, strongly inflated lobules and a densely papillose cuticle. Undivided underleaves, seen in L. leratii and L. mimula, are within subg. Crossotolejeunea unique to sect. Sordidae and are a further typical character of this section. Lejeunea anomala, a rare and little-known Neotropical species that was long placed in Ceratolejeunea because of its brown colour, is placed in this section based its close morphological similarity to L. sordida (Gradstein 2021). References Eifrig (1937), Lee (2013).