Lejeunea konratii G.E.Lee & Pócs, 2018

Lee, Gaik Ee & Pócs, Tamás, 2018, Additions to the distribution of some Palaeotropic Lejeunea (Marchantiophyta) species, with the description of Lejeunea konratii sp. nov. from Fiji, Phytotaxa 349 (1), pp. 31-38 : 34-36

Lejeunea konratii G.E.Lee & Pócs , sp. nov., Fig. 3

Type:— FIJI. Central Viti Levu: NE edge of Rairaimatuku plateau, above Naqelewai village, S from “Barclay’s Point”, 855–945 m, S 17°44.208 –264’, E 178°03.300 –573’, 24 August 2003, S. & T.Pócs 03273/ R (holotype EGR [c.per.]).

Plants dioicous?, 1.5–2.5 mm wide, irregularly and densely branched, branches spreading, with three small basal collar lobes. Stem 0.10–0.15 mm in diameter, 8–10 cells wide in stem cross-section with ca. 16–24 epidermal cells surrounding 41–55 smaller medullary cells, ventral merophyte 4–8 cells wide. Leaves imbricate, slightly recurved when dry, spreading and slightly recurved when moist. Leaf lobes 0.75–1.20 mm × 0.6–1.0 mm (when flattened), suborbicular; leaf apex broadly rounded, flat to slightly recurved; leaf margin entire; the ventral margin forming an angle of 1300 – 1500 with the keel when flattened; insertion on dorsal side 10–13 lobe cells long. Leaf cells rather uniform, quadrate to hexagonal; apical cells 20–33 × 13–20 μm, median cells 25–38 × 20–25 μm, basal cells 38–45 × 20–25 μm; cell walls hyaline, without well-developed trigones and intermediate thickenings. Cuticle smooth. Oil bodies not seen. Leaf lobules seldom reduced, 0.35–0.45 × 0.15–0.20 mm, to 1/3 the length of the lobe, at an angle of 600 – 800 to the stem, ovate, inflated along the keel; apex obliquely truncate; keel curved; free margin incurved fully; first tooth 25–50 μm long, (1)–2 cells long, oblong, erect, apex obtuse, second tooth reduced; margin between tooth and sinus 3–4 cells long, large rectangular disc cell (cell below the apical tooth) present, 25–35 × 25–35 μm. Position of hyaline papillae proximal ental ( Fig. 3 : G). Underleaves 0.35–0.45 × 0.6–0.7 mm, to 4–5 times wider than the stem, distant, reniform to wider than long; covering 1/2 of the leaf lobules; bilobed, lobes to 1/2 of underleaf length, about 15–20 cells wide, triangular, oblique; sinus narrow to broad, obtuse, U-shaped; tips obtuse; underleaf margin entire; two large basal underleaf cells differentiated; base ± auriculate, insertion line curved. Androecia not seen. Gynoecia on short lateral branches, female bracts loosely arranged, with one lejeuneaoid innovation, with 1–2 gynoecia in a row. Female bracts slightly smaller than vegetative leaves, erect-spreading when moist. Lobes 0.4–0.5 × 0.35–0.40 mm, obovate, apex obtuse, margin entire. Lobules 0.30–0.35 × ca. 0.10 mm, rarely reduced, 1/4 the width and 2/3 the length of the lobe, oblong, apex obtuse, keels straight, smooth, 0.15–0.20 mm long. Female bracteoles 0.4–0.5 × 0.25–0.35 mm, 1/2 of the perianth length, ovate with tips acute, lobes to 1/2 of female bracteole length, distant to overlapping, sinus narrow, acute, margin entire. Perianths 0.7–1.0 × 0.5–0.7 mm, emergent to 1/2 of the perianth length, obovoid, with 5 auriculate keels, the keels undulate and expanded above as auricles, 2-winged, entire (without teeth or lacinia); beak 3 cells long; stalk-like elongation of the perianth base lacking. Sporophyte and vegetative propagules not seen.

Distribution and habitat: Only known from Fiji, growing on half woody Piper stem in montane mossy (cloud) forest, at an elevation of 855–945 m, together with Lopholejeunea pocsii Sass-Gyarmati (2005: 404) .

Etymology: The species is named in honor of Dr. Matthew J. von Konrat, renown hepaticologist, Head of Botanical Collections in the Field Museum (F), Chicago and organizer of the Fiji collecting expeditions during 2008 and 2011.

Discussion: The distinguishing characters of L. konratii are 1) robust stem with 16–24 epidermal cells, 2) ventral merophyte 4–8 cells wide, 3) the (1)–2 cells long first tooth of leaf lobules, and 4) the 2-winged, auriculate and undulate keels of perianth. The reniform underleaves 4–5 times wider than stem, the smooth cuticle, and the leaf cells without well-developed trigones and intermediate thickenings are also characteristic of L. konratii . In its prominent auriculate perianth, L. konratii resembles L. papillionacea , L. dipterocarpa and L. hui , however, the former species has a very distinct and 2-winged dorsal keel. Lejeunea hui and L. dipterocarpa have two lateral and one indistinct ventral keel while L. papilionacea has much smaller underleaves. The 2-winged perianth keels observed in L. konratii also superficially resembles L. dipterota , however the latter has an almost obsolete lobular tooth. All similar species have only two ventral merophytes. The pluricellular first tooth character seems to be variable in the type specimens of L. konratii ( Fig. 3 : E,F,G), where the first lobule tooth which is 1 or 2 cells long may be found on a single shoot and only robust individuals have 2 cells. This phenomenon is also observed in L. gradsteinii ( Lee et al. 2011) and L. colensoana (Stephani) M.A.M.Renner (2010: 455) (Renner et al. 2010). The robust stem with more than two ventral merophytes in L. konratii is morphologically very similar to an as yet undescribed Lejeunea species from Papua New Guinea [H. Streimann 21509 (CBG 8402078)], however, the former differs from the latter by having the 2-winged, auriculate and undulate keels of the perianth. The discovery of L. konratii adds another Melanesian species with robust stem and more than two ventral merophytes to the genus Lejeunea . A report of all the Lejeunea with such characteristic is explained by Wei et al. (in press), however, whether the occurrence of the robust stem is related to their preferable habitat as a rheophyte in L. konratii and the undescribed Papua New Guinean Lejeunea is not justified.

Figures

FIGURE 3. Lejeunea konratii G.E.Lee & Pócs. A,B. Leaves. C. Part of plant in ventral view with perianths. D. Median cells of leaf lobe. E,F,G. Upper part of leaf lobules when flattened (hyaline papillae shown in gray). H. Cross-section of stem. N,O. Underleaves. I,M. Perianths in ventral view. J,K. Stem portion and leaf lobules. L. Perianth with bracts and bracteole. All figures drawn from the holotype, S. & T.Pócs 03273/R (EGR).