Lejeunea javanensis 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 : 30-33

3. Lejeunea javanensis G.E.Lee & Heinrichs , nom. nov. pro Taxilejeunea immersa Eifrig (1937: 96) . Fig. 3 .

Type: INDONESIA. Java: Tjibodas, in hort. mont., 1425 m alt., F. Verdoorn VI – IX 30 , Herb. Bot. Bog. 3154 (holotype JE! [c.per.]; isotype JE!). Blocking name: Lejeunea immersa Spruce (1884: 186) .

Plants autoicous, 1.0– 1.4 mm wide, irregularly and slightly branched, rarely bipinnately branched, branches erect-spreading to spreading, with three small basal collar lobes. Stem 0.07–0.1 mm in diameter, about 5 cells high in cross-section; epidermal cells 7, 25–38 μm wide, medullary cells 6, 13–18 μm wide. Leaves contiguous to imbricate, slightly recurved when dry, erect-spreading and plane when moist. Leaf lobes 0.5–0.6 mm × 0.30–0.45 mm (when flattened), ovate-oblong; leaf apex broadly rounded, usually flat; leaf margin slightly crenulate; the ventral margin forming an angle of 80°–110° with the keel when flattened; insertion 10–11 lobe cells long. Leaf cells quadrate to round; apical cells 25–33 μm × 15–20 μm, median cells 25–45 μm × 20–25 μm, basal cells 25–50 μm × 20–25 μm; cell walls hyaline, with well-developed trigones and infrequently with intermediate thickenings, 1–3 per cell, 0–1 between 2 adjacent trigones. Cuticle roughened by minute papillae. Leaf lobules sometimes reduced, 0.10–0.15 mm × 0.08–0.10 mm, to 1/3 the length of the lobe, at an angle of 70°–90° to the stem, ovate, inflated along the keel; apex obliquely truncate; keel curved; free margin incurved partially; first tooth 13–18 μm long, oblong, somewhat erect, apex obtuse; margin between tooth and sinus 3–4 cells long; large rectangular disc cell undifferentiated, cell below the first tooth 24–26 μm × 20–23 μm. Underleaves 0.2–0.3 mm × 0.25–0.40 mm, to 3 times wider than the stem, approximate to contiguous, orbicular (slightly wider than long); covering 1/2–3/4 of the leaf lobules; bilobed, lobes to 1/2 of underleaf length, about 6–8 cells wide, triangular; sinus narrow to broad, obtuse, U-shaped to V-shaped; tips acute to obtuse; underleaf margin slightly crenulate; two large basal underleaf cells differentiated; base ± cuneate, insertion line curved. Androecia 0.4–0.9 mm × 0.3–0.4 mm with bracts, on the main shoot, sometimes terminal on lateral branches. Male bracts in 3–6 pairs, crenulate without wing, apex obtuse, keels inflated. Male bracteole 1, smaller than underleaf, margin slightly crenulate. Antheridia not seen. Gynoecia on short or long branches, female bracts loosely arranged, with one innovation, 2–4 gynoecia in a lateral position. Female bracts slightly smaller than the leaf, erect-spreading when moist, not enveloping the perianth. Lobes 0.5–0.6 mm × 0.25–0.30 mm, ovate, apex obtuse, margin slightly crenulate. Lobules 0.20–0.35 mm × 0.05–0.10 mm, rarely reduced, 1/4 the width and 1/3–2/3 the length of the lobe, oblong to ovate, apex obtuse, keels straight, smooth, 0.15–0.18 mm long. Female bracteoles 0.3–0.4 mm × 0.15–0.20 mm, 2/3 of the perianth length, oblong to slightly ovate with tips obtuse, lobes to 1/3 of female bracteole length, distant, sinus narrow, acute, margin slightly crenulate. Perianth 0.5–0.6 mm × 0.25–0.35 mm, immersed between the bracts, ovate, with 5 sharp keels, the keels often with 1–2 small teeth above; beak 2–3 cells long; cells of the perianth at the keels mamillose; stalk-like elongation lacking. Sporophyte: seta 0.25–0.40 mm long; capsule ca. 0.3 mm in diameter, valves 0.3–0.4 mm × 0.2 mm at middle, rarely spreading after dehiscence; elaters ca. 0.15–0.25 mm long; spores rectangular to irregular-shaped, 25–38 μm × 13–20 μm. Vegetative propagation not seen.

Distribution:— only known from Indonesia (Java).

Discussion:— Lejeunea javanensis is characterized by the 1) slightly crenulate leaf margin, 2) leaf cells with well-developed trigones and infrequently with intermediate thickenings, 3) clearly noticeable and almost 2 cells long hyaline papilla below the first tooth, 4) ovate, approximate to contiguous underleaves, and 5) ovoid and immersed perianths with 1–2 small teeth keels above. Similar immersed perianths with toothed keels are also found in L. pectinella Mizutani (1970: 239) from Mt. Kinabalu, Sabah and L. immersa Spruce (1884: 186) from the Neotropics. Lejeunea pectinella can be distinguished by the large reniform underleaves, and the oblong perianths with an 8–10 cells long beak and L. immersa has ovate-triangular leaf lobe with narrowly rounded apex and the cuticle rarely roughened by minute papillae. Lejeunea javanensis also resembles L. fleischeri ( Stephani 1914: 560) Mizutani (1970: 238) in which both species have slightly crenulate leaf margin, well-developed trigones in leaf cells, rough cuticle by numerous minute papillae, and ovate underleaves. However, the dioicy, the fully incurved leaf lobules with large rectangular disc cell (75 μm × 20 μm), and the perianths with a 5–6 cells long beak and toothless keels readily separate L. fleischeri from the former species.

Figures

FIGURE 3. Lejeunea javanensis G.E.Lee & Heinrichs. A. Part of plant in ventral view. B–C. Leaves. D–F. Underleaves. G. Apical cells of leaf lobe. H. Cross-section of stem. I. Stem portion and leaf lobule (hyaline papilla shown by arrow). J. Median cells of leaf lobe. K. Upper portion of perianth. L. Perianth with bracts and bracteole. All figures drawn from the isotype, F. Verdoorn VI–IX 30, Herb. Bot. Bog. 3154 (JE).