Thysananthus montanus Gradstein, He & Piippo

Sukkharak, Phiangphak, 2015, A systematic monograph of the genus Thysananthus (Lejeuneaceae, Marchantiophyta), Phytotaxa 193 (1), pp. 448-450 : 448-450

14. Thysananthus montanus Gradstein, He & Piippo in Gradstein, He, Piippo & Mizutani (2002: 77).

Type: PAPUA NEW GUINEA. Morobe: Lake Wamba, 5 km S of Teptep airstrip, Teptep-Wantuat trail 10 km S of Teptep, open montane forest on ridge sloping NE, 2550–2700 m, 6°2.5' S 146°33' E, Koponen 33958b (holotype H!) .

Plants dioicous, with projecting growth, turning upwards and becoming ascending to erect, pale brown in herbarium specimens, up to 4 cm long × 1.5–2.6 mm wide. Stems rather rigid; ventral merophyte 8–10 cell rows wide; stem in cross section orbicular, 215–240 µm high × 303–329 µm wide, 14–17 cell layers high, composed of 43–48 epidermal cells surrounding 141–150 medullary cells, epidermal cells as large as medullary cells. Leaves imbricate, when dry suberect and convolute, when moist weakly convex, apical part plane, not recurved; dorsal lobe symmetrically oblong, 1.6–1.8 × 0.6–0.8 mm, apex acute-apiculate, margin entire, dorsal base auriculate, auricle 57–96 × 57–76 µm, ventral margin incurved 1/2 × leaf length; cells elongate-hexagonal with acute ends, vitta present in midportion of lobe, extending to base, 2/3 × lobe length, 8–17 cell rows wide, 13–20 cells long, marginal cells 10–12 × 5–7 µm, median vitta 25–45 × 5–7 µm, basal vitta 50–67 × 10–15 µm, trigones cordate, often coalesced, intermediate thickenings 0–2 per cell; oil bodies unknown. Lobules rectangular, 0.8–1 × 0.3–0.4 mm, 1/4–1/3 × lobe length; appendages on surface of lobule base on both sides of stem; keel without appendage; lobule apex oblique, free margin continuing into the ventral lobe margin, apex with one linear tooth, the tooth consisting of 7–9 cells, being 2–3 cells wide at base and ending in a row of 6–7 cells. Underleaves imbricate, slightly squarrose, spathulate, 1.2–1.3 × 0.6–0.7 mm, 2–3 × stem width, apex round, plane, margin entire, bases cuneate, underleaf bases not adnate with leaves; cells 27–37 × 2–5 µm. Androecia terminal-intercalary on lateral branches, bracts, and bracteoles in 6–13(–20) pairs, bracts hypostatic, 0.7–0.9 × 0.2–0.5 mm, apex acute, margins entire; antheridia 2 per bract. Gynoecia with 2 lejeuneoid innovations forming a dichasial pattern; lobe lanceolate, 2.7–2.8 × 0.8–0.9 mm, apex acute, margins entire or in upper 2/3 with triangular teeth, the teeth consisting of 3–5 cells, being 2–3 cells wide at base and ending in a row of 1–2 cells; lobules broadly ovate, 1/2 × lobe length, apex bifid, margin with triangular teeth, the teeth consisting of 3–5 cells, being 2–3 cells wide at base and ending in a row of 1–2 cells; bracteoles spathulate, 2.4–2.5 × 0.7 mm, apex emarginate to shortly bifid, entire or 1/2 × bracteole length with teeth, the teeth consisting of 3–5 cells, being 2–3 cells wide at base and ending in a row of 1–2 cells, margins plane. Perianths oblong-cylindrical, 2.6–2.7 × 0.7–0.8 mm, keels entire; beak 62–65 µm (4–5 cells) in length. Fig. 27 .

Additional illustrations:— Gradstein et al. (2002, p. 78, Fig. 49).

Distribution and ecology:— Endemic to Papua New Guinea; 1900–2300 m; on tree trunks, lianas, and branches in open montane forests. Fig. 5K .

Representative specimens:— Papua New Guinea. EASTERN HIGHLANDS: Gahavisuka National Park, Thiers 3656 (G).— MILNE BAY: Fergusson Island, Brass 27072 (L).— MOROBE: Gumi divide, Streimann 22707 (JE, LAE); Mt. Kaindi, Streimann 22511 (LAE); Araulu logging area, Streimann 13639 (LAE); Nauti logging area, upper Watut river, Streimann 17150 (LAE); Kaisenik logging area, Shea 6359 (NICH).

Taxonomic notes:— The type specimen was previously identified as T. planus (= T. retusus ). By its oblong, entire leaves T. montanus approaches T. retusus but differs from the latter by (1) leaves when dry convolute (widely spreading, loosely reflexed or plane in T. retusus ), (2) dorsal base auriculate (cordate in T. retusus ), (3) leaf cells elongate-hexagonal, vitta 8–17 cell rows wide (subisodiametric, 4–6 in T. retusus ), (4) being dioicous (autoicous in T. retusus ), and (5) entire perianths (toothed perianths in T. retusus ). Thysananthus montanus is morphologically most similar to T. mollis . The latter species differs essentially by its leaf, which is lanceolate in outline, the emarginate-lunulate apex of the underleaf, and the toothed perianths.

The female bracts and bracteoles in Thysananthus montanus vary from entire to dentate.

Thysananthus ( Lejeuneaceae , Marchantiophyta) Phytotaxa 193 (1) © 2015 Magnolia Press • 45

Figures

FIGURE 5. Distribution of Thysananthus species. A. Thysananthus amazonicus (Spruce) Schiffn. B. Thysananthus spathulistipus (Reinwardt, Blume & Nees) Lindenb. C. Thysananthus convolutus Lindenb. D. Thysananthus mollis Steph., E. Thysananthus pancheri (Steph.) Hürl. F. Thysananthus anguiformis (Hook.f. & Taylor) Taylor ex Gottsche, Lindenb. & Nees G. Thysananthus comosus Lindenb. H. Thysananthus fruticosus (Lindenb. & Gottsche) Schiffn. I. Thysananthus aculeatus Herzog. J. Thysananthus appendiculatus Steph. K. Thysananthus montanus Gradst., X.-L. He & Piippo. L. Thysananthus retusus (Reinw., Blume & Nees) B.M.Thiers & Gradst. M. Thysananthus gottschei (Jack & Steph.) Steph. N. Thysananthus ciliaris comb. nov. O. Thysananthus discretus Sukkharak & Gradst.

FIGURE 27. Thysananthus montanus Gradst., X.-L. He & Piippo. A. Portion of shoot, ventral view. B. Leaves, ventral view. C. Underleaves, ventral view. D. Female bracts, ventral view. E. Female bracteole. F. Perianth, dorsal view. G. Perianth, ventral view. H. Leaf apices. I. Margin cells of leaf lobe. J. Median cells of leaf lobe. K. Basal cells of leaf lobe. L. Leaf lobule apex. M. Cross section of stem. (All from the holotype).