Lejeunea koordersii 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 : 33

4. Lejeunea koordersii G.E.Lee & Heinrichs , nom. nov. pro Taxilejeunea grandistipula Stephani (1914: 504) . Fig. 4 .

Type: INDONESIA. Java: in rupibus, 6000´, Koorders s.n. (holotype G, not seen). Blocking name: Lejeunea grandistipula Stephani (1886: 89) .

Plants dioicous, 0.8–1.25 mm wide, irregularly and densely branched, sometimes bipinnately branched, branches erect-spreading to spreading, with three small basal collar lobes. Stem 0.10–0.15 mm in diameter, about 6 cells high in cross-section; epidermal cells 7, 25–38 μm wide, medullary cells 9–10, 18–25 μm wide. Leaves approximate to contiguous, strongly recurved when dry, erect-spreading, slightly recurved and concave when moist. Leaf lobes 0.65– 0.70 mm × 0.40–0.45 mm (when flattened), ovate-triangular; leaf apex cuspidate, slightly recurved; leaf margin entire; the ventral margin forming an angle of 40°–60° with the keel when flattened; insertion 11–12 lobe cells long. Leaf cells somewhat differentiated from base to apex, abruptly becoming smaller at the middle of the leaf, mostly quadrate to hexagonal, basal cells more or less elongate; apical cells 13–20 μm × 13–20 μm, median cells 20–25 μm × 13–20 μm, basal cells 38–50 μm × 20–25 μm; cell walls hyaline, with small trigones and without intermediate thickenings. Cuticle roughened by numerous minute papillae. Leaf lobules sometimes reduced, 0.17–0.20 mm × 0.10–0.13 mm, to 1/4 the length of the lobe, at an angle of 60°–70° to the stem, ovate, inflated along the keel; apex constricted, Ushaped notch; keel curved; free margin flat; first tooth 30–38 μm long, oblong, erect, apex obtuse; margin between tooth and sinus 4 cells long, large rectangular disc cell undifferentiated, cell below the first tooth 25–28 μm × 13–15 μm. Underleaves 0.35–0.40 mm × 0.45–0.55 mm, to 3 times wider than the stem, approximate to contiguous, ovate (slightly wider than long); covering completely the lobules; bilobed, lobes to 2/3 of underleaf length, about 15 cells wide, triangular, distant; sinus broad, obtuse, V-shaped; tips apiculate to cuspidate; underleaf margin entire; two large basal underleaf cells differentiated; base cordate to auriculate, insertion line curved. Gynoecia on short or long lateral branches, occasionally on main shoots, female bracts loosely arranged, with one innovation, with 2–3 (5–6) 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 × 0.15–0.20 mm, ovate to somewhat oblong, apex acute, margin entire. Lobules 0.35–0.40 mm × 0.10–0.15 mm, rarely reduced, 1/3–1/2 the width and 3/4 the length of the lobe, oblong, apex obtuse, keels straight, smooth, 0.20–0.25 mm long. Female bracteoles 0.55–0.60 mm × 0.3–0.4 mm, 1/3–1/2 of the perianth length, ovate with tips acute, lobes to 1/3–1/2 of female bracteole length, distant, sinus narrow to broad, acute to obtuse, margin entire. Perianths (0.8–0.9) 1.20–1.25 mm × (0.5) 0.6–0.8 mm, emergent to 1/2–2/3 of the perianth length, pyriform (obovoid), with 5 keels; beak 2–3 cells long; cells of the perianth at the keels entire; stalk-like elongation lacking. Androecia, sporophyte and vegetative propagation not seen.

Distribution:— only known from Indonesia (Java).

Further specimen examined:— INDONESIA. Java: Gedeh Geger-Bintang Gipfel, Fleischer 43 (G).

Discussion:— Lejeunea koordersii is easily recognised by 1) the strongly recurved leaves when dry (tend to roll themselves around the stem), 2) cuspidate leaf apex, 3) somewhat differentiated leaf cells from base to apex (abruptly becoming smaller at the middle of the leaf and basal cells more or less elongate), 4) the poorly developed trigones and without intermediate thickenings, 5) flat free margin of leaf lobules, 6) the constricted and curved (more or less U-shaped notch) apex of leaf lobules, 7) the large, contiguous, and ovate underleaves with cordate to auriculate bases, and 8) the pyriform perianths. Similar leaf cells and lobules are found in L. contracta Mizutani (1970: 248) (endemic to Mt. Kinabalu, Sabah), however, L. koordersii can be distinguished by the cuspidate leaf apex. The constricted, curved and the “preapical” tooth at the very end of the lobule (see Fig. 4 : N, preapical tooth shown by arrow) at the junction with the ventral lobe margin in both species is uncommon for the genus Lejeunea . However, the preapical tooth is typical for several genera of Lejeuneaceae e.g., Cheilolejeunea ( Spruce 1884: 79) Schiffner (1893: 118) species [ C. imbricata ( Nees 1830: 42) Hattori (1957: 1) , C. longiloba (Steph. ex Hoffmann 1935: 114) Engel & Tan (1986: 294) ] and Drepanolejeunea ( Spruce 1884: 186) Stephani (1891: 209) species [ D. fragilis Bischler (1964: 123) , D. lichenicola ( Spruce 1884: 191) Stephani (1913: 335) ].

Figures

FIGURE 4. Lejeunea koordersii G.E.Lee & Heinrichs. A. Part of plant in ventral view. B–C. Leaves. D–F, L. Underleaves. G. Perianth with bracts and bracteole. H. Female bracts. I. Cross-section of stem. J. Upper part of leaf lobule when flattened (hyaline papilla shown in gray). K. Female bracteole. M. Apical cells of leaf lobe. N. Stem portion and leaf lobule (preapical tooth shown by arrow). O. Median cells of leaf lobe. P. Basal cells of leaf lobe.All figures drawn from Fleischer 43 (G).