Lejeunea streimannii Y.M.Wei & R.L.Zhu, 2018

Wei, Yu-Mei, Tang, Qi-Ming & Zhu, Rui-Liang, 2018, Lejeunea streimannii (Lejeuneaceae, Marchantiophyta), a remarkable new species with robust stems and 5 (or 6) - keeled perianths from Papua New Guinea, Phytotaxa 338 (2), pp. 189-194 : 190-191

Lejeunea streimannii Y.M.Wei & R.L.Zhu , spec. nov. Fig. 1

Type:— PAPUA NEW GUINEA. Enga province: Mape Creek, Mount Hagen-Wapenamanda Road, 17 km SE of Wapenamanda, 5°46’ S, 143°57’ E, 2500 m, Urticaceae dominated slope, on the ground, 29 Jun. 1982, H. Streimann 21509 (holotype CBG 8402078!, isotype EGR).

The new species is characterized by the dioicous plants, robust stem with 18‒21 rows of cortical cells and a ventral merophyte 4‒6 cells wide, small lobules with unicellular first tooth and blunt second tooth, bifid underleaves with a cordate base, inflated perianth with 5(or 6) crenate, weakly winged keels.

Dioicous. Plants yellowish in herbarium, 2−4 cm long. Shoots 1.0− 1.6 mm wide, irregularly branched, of the Lejeunea- type, leaf sequence of vegetative branches lejeuneoid. Stem 170−200 μm in diameter, in transverse section suborbicular, 18−21 rows of cortical cells surrounding 26−39 smaller medullary cells, cortical cells subquadrate to oblong, 18−38 × 20−30 μm, medullary cells ± isodiametric, 15−30 × 13−25 μm; ventral merophyte 4−6 cells wide. Rhizoids at base of underleaves, few, tufted, usually hyaline, rhizoid disc absent. Leaves imbricate, diverging from stem at an angle of 45°−60°; leaf lobules asymmetrically triangular-ovate, usually concave, 0.8−1.5 mm long, 0.8−1.5 mm wide, margin entire, dorsal margin arched, apex rounded, strongly incurved; leaf lobules subovate, slightly inflated, 1/6−1/5 as long as the lobes, lateral free margin usually slightly incurved (except for apex), apex obliquely truncate, with two teeth, first tooth unicellular, usually rectangular, second tooth blunt, sometimes obsolete, keel slightly arched, smooth, hyaline papilla oblong, 30 × 15 μm, situated at the proximal base of first tooth. Cells of leaf lobe thin-walled, trigones small, intermediate thickenings 0−1 per cell wall, small; margin cells quadrate to rectangular, 13−20 × 8−15 μm, median cells hexagonal, 18−35 × 13−25 μm, basal cells similar to median ones in shape, but slightly larger, cuticle smooth. Oil bodies and ocelli not seen. Underleaves imbricate to distant, wider than long, 3−4.5 times as wide as stem, bilobed to 1/3−1/2 their length, sinus narrow with obtuse to acute base, insertion line deeply arched, base cordate. Androecia terminal, rarely intercalary, usually on very short lateral branches, bracts in 2−6 pairs, bracteoles 1−2, borne only at the basal portion of the androecium, smaller than ordinary underleaves. Gynoecia usually on short branches, with 1−2 lejeuneoid innovations; bracts obovate, 0.6−0.7 mm long, 0.3−0.5 mm wide, deeply and unequally bifid, the lobe broadly ovate, apex rounded to obtuse-rounded, margin entire, bract lobule rectangular, 2/3−4/5 as long as the bract lobe, apex obtuse, keel 2/3 as long as the lobule; bracteole connate with bracts on both sides at base, oblong, 0.6−0.7 mm long, 0.4−0.5 mm wide at middle, margin entire, apex bilobed to 1/4−1/3 its length. Perianths about 1/2−2/3 exserted, obovate, 1.1−1.4 mm long, 0.6−0.7 mm wide at middle, inflated, with 5(or 6) keels (2−3 ventral, 2 lateral, 1 dorsal), keels usually crenulated, sometimes with weak wing, surface of perianth smooth, beak short, 1 cell long. Asexual reproduction not seen.

Etymology:— This new species is dedicated to the late Heinar Streimann who collected the type specimens.

Ecology and distribution:— Lejeunea streimannii occurs on the ground and shaded rock face in an Urticaceae dominated slope or disturbed lower montane forest beside road at ca. 1300 to 2500 m. It is thus far known only from Papua New Guinea.

Additional specimen examined. PAPUA NEW GUINEA. Morobe Province: Mt. Kaindi Road, 3 km W of Wau, 7°20’ S, 146°42’ E, 1300 m, disturbed lower montane forest beside road, on shaded rock face, 9 Jan. 1983, H. Streimann 33431 (paratype CANB 778500!).

Figures

FIGURE 1. Lejeunea streimannii Y.M.Wei & R.L.Zhu. A: part of plant with perianth, ventral view. B: part of plant with two androecia, ventral view. C, D: leaves, ventral view. E, F: a perianth showing its keels, ventral view (E), dorsal view (F). G, S: transverse sections of stem. H: marginal cells of leaf lobe. I: median cells of leaf lobe. J: basal cells of leaf lobe. K, L: transverse section of perianths. M, O: female bracts. N: female bracteole. P: leaf lobule with part of stem. Q, R: apex of leaf lobules. T: androecium. U, V: underleaves.A, C−S and U−V from H. Streimann 21509 (holotype), B and T from H. Streimann 33431 (paratype).