Plants small, main shoots ca. 400–750 µm wide (excluding acuminate dorsal lobe apices), often dark brown to almost black. Leading stem to 30mm long and to 115µm in diam. 7–8 cells wide, 18–22 cortical cells and 18–24 medullary cells, both with firm walls, and irregularly-shaped lumen; cortical cells slightly smaller than medullary cells, and the walls of the former often slightly thicker and deeper pigmented than those of the medullary cells. Branching often regularly pinnate, occasionally bipinnate. Frullania-type branching (FB) only. Initial branching appendages associated with FB variable: Chevalieri-type, Rostrata-type, Apiculata-type, and/or Deplanata-type; BL1 never with two saccate appendages. Stemleavesof main branch± flat when dry and wet, dorsal lobes contiguous to loosely imbricate, rarely remote; broadly ovate to asymmetrically elliptical; to 475 µm long × 345 µm wide; antical base extending beyond the farther edge of the stem (by 1–1.5× the stem width); dorsal lobes abruptly decurved, typically with long-acuminate to apiculate apices, apices of 2–3 cells near base and extending to 3–5 cells in length and ca. 50 µm long, occasionally lobes tapering to triangular, acute, apices; non-auriculate at the base, and with entire margins and smooth dorsal cell surface. Lobules ± remote from the stem (lobule attached to stem by 2–3 cells) and at angles of 35–55º with the stem so that lobules tilted outwards; lobules slightly darker or similar in colour to other organs; uniformly inflated, smooth, obovoid, (orbicular in cross-section with up to 20 cells in circumference) and ca. 1.5–1.75× long as wide, to 200µm long × 125 µm wide (ca. to 9–10 cells in length); lobuli ± large in proportion to the leaf-lobe (lobule area obscuring 0.35–0.75× the exposed area of the dorsal lobe), somewhat dorsiventrally compressed near mouth as compared to gibbous upper half, the opening extending along the abaxial lobule margin; immediately above the slit of the lobule mouth there is usually an enlarged and elongated cell, cell cavity to 20 µm long, 1.5–2× long as wide, the free wall, thick, to 10 µm, forming an angular protuberance that projects outwards; the free margin of lobular mouth inconspicuously crenulate-sinuate, hyaline only at marginal cells of the mouth, lobule apex obtuse. Stylus, distinct, subtriangular to triangular, up to 75 µm long, (2) 3–4 cells wide at base, (3) 4–7 (9) cells in total, occasionally with a slime papilla at the apex [key in Engel, 1978: terminates in a unicellular row of two cells]. Underleaves of leading stems, ± medium in size (ca. 0.5 the size of leaf lobes); at best only contiguous with lobules, underleaves otherwise distant to contiguous from each other; usually ca. long as wide, or occasionally slightly wider than long, suborbicular to obovate in outline, to 220 µm long × 190 µm wide, 1.5–3.0 (3.2)× as wide as the stem, broadest at middle, 10–16 cells wide; lateral margins entire or with minor angulations of 1–3 (4) cells, i.e., very small teeth; apex of underleaf bilobed to 0.4–0.5 its length, lobes separated by a very narrow U to V-shaped sinus, lobes 4–6 cells wide at base (excluding angulations if present), with acute to subacute apices. Rhizoid-initial area present near base of underleaf, rhizoids rarely seen, subhyaline, in short bundles. Secondary branching either similar in size to the main stem or with pseudo-microphyllous branching, lobules of secondary stems only slightly smaller in size to those of the main stem (to 125µm long × 85µm wide), but lobes (to 175µm long × 115µm wide) and underleaves (to 125 long × 125µm wide) of secondary branches markedly smaller than those of leading stems. Dorsal lobes of secondary branching often with longer acuminate to apiculate apices than those of the main stem.
Lobe marginal cells rectangular to quadrate, subhyaline walls subequally thickened; median cells ± subquadrate, rectangular to distinctly 5–6-sided, hyaline walls subequally thickened, with intermediate thickening rare to occasional, cell cavities of median cells brownish red, (9) 11.5–17.5 (25) µm long × (10) 11 – 15 (17.5) µm wide; cells becoming gradually larger basally, cavities of the basal median group of cells to 32.5 µm long × 20 µm wide; walls of basal cells increasing in thickness, and with rare to occasional, indistinct, intermediate thickenings. Median cells of underleaves generally with ± subequally thickened, nodulose, hyaline walls and intermediate thickenings, cell cavities to 20 µm long X 12.5 µm wide. Median cells oflobuleca. 1.75–2× longer than wide, cell cavities to 25 µm long × 12.5 µm wide, walls flexuose throughout the lobule, with indistinct trigones and small nodulose intermediate thickenings, becoming increasingly flexuose towards the lobule mouth). Oil-bodies : no records. Asexual reproduction;none known.
Dioicous. Androecia subspherical (to 400µm long × 500µm wide) to shortly spicate (to 750 µm long × 550 µm wide), 2–4 (5) pairs of closely imbricate bracts, sessile or terminal on very short-stalked Frullania-type branches, stalk with 1 (2) vegetative leaf lobes. Gynoecia terminal, gynoecial branches either 1) with the first vegetative branch developing 2 (3) vegetative leaves posterior to the ♀ bracts and bracteoles or 2) with subfloral innovations immediately posterior to the ♀ bracts and bracteoles. ♀ bracts and bracteoles in 1–4 closely imbricate cycles. Innermost bract unequally bilobed; bract-lobe asymmetrically elliptical-lanceolate to ovate, ca. to 750 µm long × 400 µm wide, tapering to a subacute to obtuse apex, the margins entire; bract-lobule, length ⅞ that of bract-lobe, but ca. 0.5–0.75× the size of the lobe, broadly lanceolate, with an acute to subacute apex, 1 small stylar-like tooth at the base of the lobule. Innermost bracteole free from bracts, oblong to suborbicular in outline, ca. ½–⅔ bilobed, the sinus narrowed; lobes ovate-triangular, with acute apices, and without marginal teeth. One archegonium per gynoecium. Perianth freely emergent, oblong-clavate, to 1400 µm long (excluding perianth beak) × 625 µm wide, exterior smoothly trigonous, keels obtuse, tapering towards the apex into a short cylindrical beak, becoming extended towards the mouth; perianth beak with a smooth rim or mouth, but the inner beak surface densely covered with large single-celled protuberances (10–20 µm long), cells of the perianth interior not elevated.
Valves of capsule to 300–360 µm long × 180–220 µm wide; elaters to 14–16 (20) in total, arrangement on two alternating valves, e.g., 1+2+(1) or 2+3+(1), elaters usually arranged in 2 rows on the valve, rarely in 3 rows, unispiral, to 220µm long × 20 µm wide, irregularly rugose-granulate surface. Epidermal cell layer: 14–16 cells wide; cell wall thickenings extending toward the centre of the tangential face for a short distance, as short rounded or obtuse lobes, the juxtaposed corner thickenings forming 2-3 (4) lobed figures, intermediate thickenings occurring near the middle of the longer walls (See Fig. 3.20a). Inner cell layer: cells to 20 µm long by wide, individual cells elevated into sharp to obtuse keels, juxtaposed to form ridges arranged longitudinally and parallel with the long valve axis and as hexagonal rings; surface ultrastructure of the inner cell layer with distinct, fine, granular perforations. Spores globose, 40–50 µm at widest axis, which is interspersed with 7–9 rosettes; each rosette 3.5–4.5 µm in diam., and bearing a ring of 6–8 conspicuous primary projections; the primary projections (0.75) 1.25–1.75 (2.0) µm high × 0.5–1.25 µm wide at base (often with a 1.5–2:1 length to width ratio), and taper gradually to rounded apices, without divisions of any kind and never bearing secondary deposits; between rosettes the spore wall randomly distributed with low lying tubercles; the spore wall papillae otherwise densely distributed.
Affinities, differentiation & variation:
Engel (1978) provided a distinction between F. lobulata and other Frullania species from the Brunswick Peninsula, including F. microcaulis. Frullania lobulata can immediately be distinguished from both F. microcaulis and F. truncata by the long-acuminate dorsal leaf-lobe apices. Frullanialobulata also differs from F. microcaulis by the dioicous state and the large lobules in proportion to the dorsal lobes. Frullanialobulata also has an interesting spore and capsule wall morphology that has not been observed in any other Frullania species to date: the cells of the inner capsule wall layer elevated into sharp to obtuse keels, juxtaposed to form ridges arranged longitudinally and parallel with the long valve axis and as hexagonal rings; and the spore wall randomly distributed with low lying tubercles between rosettes.
Geographic distribution & ecology:
Engel (1978): Chile, Tierra del Fuego and southern Patagonian Channels (Brunswick Peninsula) where it commonly found on bark of Nothofagus and less often on Libocedrus and Drimys in the evergreen Nothofagus forest region, and also occasionally on rotted trunks. Engel (1978) noted that the reports from the Valdivian region, by Stephani in 1900, and Juan Fernandez, by Herzog in 1942 required confirmation. Frullania lobulata had also been reported for the Falkland Islands by Taylor and Hooker (1847), but Engel (1987) excluded the species from the Falklands as 1) Engel ibid believed the specimen on which the record was based by Taylor and Hooker was actually another species, F. boveana, and 2) based on his own field experience, F. lobulata was restricted to tree bark in the rain forests of the Magellanian region.
Notes: Engel (1978) noted that Hooker, in his 1820 description and discussion of F. lobulata (as Jungermannia lobulata), made no mention of the acuminate dorsal lobe apices, which Engel recognised as of considerable importance in the identification of this species. Engel (1978) should be consulted for a detailed analysis of the original material and Hooker’s, 1820, original description and illustrations.