Lejeunea splendida (Eifrig) G.E.Lee & Heinrichs, 2018

Lee, Gaik Ee, Bechteler, Julia & Heinrichs, Jochen, 2018, A revision of unrevised taxon names in the former genus Taxilejeunea (Marchantiophyta: Lejeuneaceae) from Asia, Phytotaxa 358 (1), pp. 26-48 : 38

7. Lejeunea splendida (Eifrig) G.E.Lee & Heinrichs , comb. nov., Fig. 7 .

Taxilejeunea splendida Eifrig (1937: 88) .

Type: INDONESIA. Java: Prov. Preanger, Vulkansee Telaga Bodas, Schiffner 2917 (holotype JE! [c. per.]).

Plants dioicous, 1.3–2.0 mm wide, irregularly and slightly branched, rarely bipinnately branched, branches spreading, with three rather large basal collar lobes. Stem 0.08–0.15 mm in diameter, about 8 cells high in cross-section; epidermal cells 7–9, 38–75 μm wide, medullary cells 20–35, 20–38 μm wide. Leaves imbricate, plane when dry, spreading and plane when moist. Leaf lobes 0.7–1.0 mm × 0.6–1.0 mm (when flattened), ovate–triangular to orbicular; leaf apex narrowly rounded, flat; leaf margin weakly crenulate; the ventral margin forming an angle of 110°–150° with the keel when flattened; insertion 10–13 lobe cells long. Leaf cells rather uniform, round to hexagonal; apical cells 25–33 μm × 13–20 μm, median cells 38–50 μm × 20–25 μm, basal cells 38–50 μm × 20–25μm; cell walls hyaline, with well-developed trigones and conspicuous intermediate thickenings, 1–2 (3) per cell, 0–1 between 2 adjacent trigones. Cuticle smooth. Leaf lobules occasionally reduced, 0.2–0.3 (0.35) mm × 0.15–0.20 (0.25) mm, to 1/3–1/4 the length of the lobe, at an angle of 50°–90° to the stem, ovate, inflated along the keel; apex obliquely truncate with two teeth (especially robust individuals), the first tooth 1–2 cells long (2 cells long on robust plants) and the second tooth blunt and short; keel curved; free margin incurved fully, sometimes abruptly flattened toward the apex; apical margin between first tooth and sinus 4 cells long, large rectangular disc cell undifferentiated, cell below the first tooth 20–25 μm × 13–18 μm wide. Underleaves 0.25–0.35 (0.55) mm × 0.30–0.35 (0.5) mm, to 3 times wider than the stem, distant, suborbicular; covering 1/3–1/2 of the leaf lobules; bilobed, lobes to 1/2–2/3 of underleaf length, about 8–11 cells wide, triangular; sinus broad, acute to obtuse, U-shaped to V-shaped; tips acute to obtuse; underleaf margin weakly crenulate; two large basal underleaf cells differentiated; base ± cuneate, insertion line curved. Androecia 0.4– 1.0 mm × 0.35–0.40 mm with bracts, on the main shoots or lateral branches, occasionally terminal on branches. Male bracts in 2–8 pairs, crenulate with wing, apex obtuse, keels inflated. Male bracteole 1, smaller than underleaf, margin weakly crenulate. Antheridia 2 per bracts. Gynoecia on short or long lateral branches, female bracts loosely arranged, with 1–2 innovations, with 1–2 gynoecia in a lateral position. Female bracts smaller than the leaf, erect-spreading when moist, not enveloping the perianth. Lobes 0.5–0.6 mm × 0.30–0.35 mm, obovate to ovate, apex acute to obtuse, margin weakly crenulate. Lobules 0.60–0.75 mm × 0.25–0.30 mm, rarely reduced, 1/3–1/2 the width and 2/3 the length of the lobe, ovate to oblong, apex acute to obtuse, keels straight, smooth, 0.3–0.4 mm long. Female bracteoles 0.6–0.8 mm × 0.4–0.5 mm, 1/2 of the perianth length, ovate with tips acute, lobes to 2/3 of female bracteole length, approximate, sinus narrow, acute, margin weakly crenulate. Perianths 0.8–1.0 mm × 0.35–0.50 mm, emergent to 1/2 of the perianth length, pyriform to somewhat oblong, with 5 keels; beak 2–3 cells long; cells of the perianth at the keels entire, rarely mamillose; stalk-like elongation present, 0.2–0.3 mm long. Sporophyte and vegetative propagation not seen.

Distribution:— only known from Indonesia (Java).

Further specimen examined:— INDONESIA. Java: Tjibodas, Mt. Pangerango, V. Schiffner 3160 (JE).

Discussion:— The characteristic features are 1) the stem with 7–9 rows of epidermal cells, 2) the weakly crenulate margin of leaves, underleaves, female bracts and bracteoles, 3) leaf cells with well-developed trigones and conspicuous intermediate thickenings, 4) the fully incurved free margin of leaf lobule, 5) first tooth of leaf lobule 1–2 cells long, 6) winged male bracts, and 7) the pyriform perianth. The species is rather similar and part of a group of Lejeunea species with a 1–2 cells long lobule tooth, e.g., the Malaysian L. gradsteinii Lee et al. (2011: 30) , the New Guinean L. candida ( Pócs 1997: 8) Schuster (1998: 87) , the Australian L. oracola Renner et al. (2010: 450) and the Fijian L. konratii Lee & Pócs (2018: 34) . However, L. splendida has 7–9 epidermal cells (all similar species have 7 epidermal cells except L. konratii , which has 16–24) and leaf cells with conspicuous intermediate thickenings (usually without for all similar species). Furthermore, the hyaline papilla in L. candida is attached to the inner base of the first tooth, the perianth in L. oracola is without keels, and the perianth keels in L. candida and L. gradsteinii are usually cordate at the apex.

Figures

FIGURE 7. Lejeunea splendida (Eifrig) G.E.Lee & Heinrichs. A–B. Part of plant in ventral view. C–E. Leaves. F,K. Underleaves. G,I. Stem portion and leaf lobule. H,J. Upper part of leaf lobules (hyaline papilla shown in gray). L. Perianth. M. Perianth with bracts and bracteole. N. Median cells of leaf lobule. O–P. Cross-section of stem.All figures drawn from the holotype, Schiffner 2917 (JE).