Frullania knightbridgei

Detailed description

Plants corticolous, forming olive-green, copper-brown, to black patches. Leading stem 15–25 mm long, to 90µm diameter, 6–9 cells wide, little differentiation between cortical cells and medullary cells, lumen irregularly shaped. Branching regularly pinnate, occasionally bipinnate or tripinnate, branches with progressively smaller leaves; Frullania-type branching. Stem leaves of main branch flat, slightly imbricate to contiguous, suborbicular to broadly ovate, to 375 × 350 µm, distal margins incurved, dorsal margins extending beyond the farther edge of the stem, apices rounded, non-auriculate and ± subtruncate at the base, margins entire, dorsal surface smooth. Lobules remote from the stem, often bicoloured, basal 2–5 cells hyaline to subhyaline, otherwise olive-green to brown; cylindrically helmet-shaped; lobules ± medium, 110–200 × 60–100 µm (up to 12–14 cells high × 6–8 cells wide); ± equally initiated throughout, opening wide; mouth nearest stylus, truncate at base, mouth becoming crenulate-sinuate; lobule hyaline near mouth, lobule apex obtuse, surface smooth. Stylus medium in size (1/3–2/3× lobule length), ± triangular, up to 60 × 50 µm, 4–7 cells wide at base, 10–30 cells in total. Underleaves of leading stems bilobed, obovate to rotundate, contiguous to distant from each other, usually as long as wide, occasionally slightly longer than wide, 2–4× the stem in width, to 100–175 × 100–150 µm, broadest at middle, free lateral margins entire; apex bilobed to 1/3–1/2 its length, lobes separated by a V-shaped sinus, each lobe 9–14 cells wide at base with blunt to subacute or rounded apices. Rhizoid initial area present near base of underleaf, rhizoids conspicuous, subhyaline, in bundles, to 400 µm long. Lobules of secondary stems ± similar size to main stem. Leaf-lobe: to 20 × 35 cells; with a band of 10–12 enlarged cells at lobe base and extending out towards the apex, up to 6 cells wide at the widest region. Lobe marginal cells ± rectangular to subquadrate, to 8 × 6 µm, walls hyaline, subequally thickened, cell cavities brownish red. Cells of the middle region of the lobe ± dimorphic; Type 1: 4–6 rows of median cells, to 30.0 × 22.5 µm, similar in size to basal cells; Type Two: cells gradually becoming reduced in size (median cells to 15 × 10 µm). Both cell types pentagonal or hexagonal, hyaline walls subequally thickened, intermediate thickening absent, wall thickness to 2.75 µm wide, median cell cavities brownish red. Cavities of basal cells to 40 × 25 µm; walls semi-straight with indistinct trigones lacking intermediate thickenings, brownish red. Median cells of underleaves variable, with heavily equally-thickened walls, hyaline trigones, intermediate thickenings indistinct. Median cells of lobule mostly as long as wide, cell cavities to 14 × 9 µm; cells near lobule mouth, irregular in shape with flexuose walls, trigones indistinct, occasionally with nodulose intermediate thickenings; towards apex cells gradually becoming regular in shape, quadrate to rectangular with cell walls becoming semi-straight. Oil bodies of lobe median cells dimorphic.Type 1: 1-3 per cell, large,2–9 µm diameter, 5–13 × 4–12 µm, ovoid, ellipsoidal or spherical, finely granular, these occupying 3/4 to almost the entire cell lumen. Type 1 oil bodies larger than chloroplasts. Type 2: 2–4 oil bodies per cell, 1–5 µm diameter, 2-6 × 1-4 µm, spherical, ovoid or ellipsoidal, subhyaline, appearing homogeneous. Oil bodies of lobule and underleaf of Type One. Asexual reproduction unknown. Plants dioecious. Androecia subspherical to spicate, bracts terminal, in 2-6 pairs, on short-stalked branches arising from main stem. Gynoecia terminal on main or leading stem bearing a subfloral innovation arising 3–4 bract-pair cycles back from the perianth or gynoecia. Archegonia 1 per gynoecium. Perianth 900 × 500 µm, plicate, surface smooth, oblong-ovate, apex tapering to a short cylindrical beak. Spores globose, 35–45 µm.