Plants medium too large (main shoots (600)700–900(1100) µm wide), usually corticolous, occasionally saxicolous, forming yellowish-brown to dark brown patches, closely appressed to loosely attached to substrate. Leading stems to 25mm long and 80–150 µm in diam., (7)8–10(12) cells wide; cortex of 15–25 cells, the cells generally smaller than 20–25 medullary cells, both cortical and medullary cells with heavily thickened walls, but the cortical cells more heavily pigmented (yellow-brown). Branchingirregularly pinnate to bipinnate, rarely tripinnate, of Frullania-type only. First branch underleaf (BUL1) usually bilobed, 1 unlobed, ventral explanate or at most sulcate segment + 1 unlobed dorsal segment; first branch leaf (BL1) bifid, 1 ventral saccate segment + 1 dorsal (often lingulate) segment. Main stem leaves virtually flat when dry and wet, often densely imbricate, lobe elliptical, (350)520–770(820) µm long × (290)410–620(630) µm wide, often with strongly incurved distal margins, when flat with widely rounded to nearly subtruncate apices, dorsal margin arching 1–1.5Χ the stem width beyond the opposite edge of the stem, base cordate (usually both dorsal and ventral bases auriculate-appendiculate); surface smooth; margins entire. Lobules often incumbent or occasionally parallel to the stem, whenincumbent, dense and partially imbricate to each other, occasionally contiguous or distant, obscuring approximately 0.25 to 0.5 of lobe; the lobules campanulate, ± dorsiventrally flattened, curved to subparallel sides with wide rounded apices, often constricted above the mouth, the lobule usually with a conspicuously large globose, thick-walled cell occupying the base of the lobule; the lobules ca. 2Χ long as wide, (220)260–440(530) µm long × (90)150–250(280) µm wide, and to 80 cells in circumference at broadest region; lobule similar in colour to leaf-lobe and underleaf but becoming hyaline towards the smooth margined mouth (sometimes giving the lobule a bicoloured appearance). Stylus 8–20 cells in total, 50–80 µm long, base ovate to nearly orbicular, up to 5 cells wide at broadest region, with a minute apical tooth consisting of a row of 2–4 uniseriate cells. Underleaves of leading stems usually slightly imbricate to contiguous, rarely distant, almost as wide as long, (160)190–430(450) long µm × (130)140–380(400) µm wide, ± obovate, cuneate-based, broadest in distal third (30-40 cells wide)where lateral margins occasionally obtusely dentate (lobes above lateral angles always edentate); underleaf apex 0.25–0.3 bilobed, the sinus narrowly to broadly U-shaped, lobes usually with obtuse to rarely subacute apices,rhizoid-initial disk situated near underleaf base. Rhizoidssubhyaline, 130–200 µm long. Plant never microphyllous, branch leaves and underleaves similar in form and size to those of main stem. Asexual reproductionnone.
Lobemedian cellswith convex to nodose and often asymmetric thickenings at the cell angles, the intervening walls ± sinuous with nodulose intermediate thickenings, often the intermediate thickenings becoming confluent with trigones, both the trigones and intermediate thickenings (if present) hyaline, wall thickness to 4.5 µm wide (without intermediate thickening), the cells irregularly polygonal, slightlylonger than broad, with cell cavities yellow-brown to red-brown, (8)13–18(20) µm long × (5)7–12(14) µm wide, the cells becoming gradually larger basally; lobe basal group of cells with large bulging trigones and thin intervening walls, and rarely with nodulose intermediate thickenings, the cell cavities(16)18–28(31) µm long × (7)8–14(18) µm wide; marginal lobe cells ± subequally thickened walls, occasionally with intermediate thickenings, the cells subquadrate to rectangular, with cavities (8)9–11(12) µm long × (5)6–8(9) µm wide. Underleaf median cells with weak sinuous walls, and distinct convex trigones and nodulose intermediate thickenings, the cell cavities(10)12–19(24) µm long × (6)7–9(10) µm wide. Lobule median cells withstrongly sinuose walls, indistinct trigones and strongly nodulose intermediate thickenings, the middle lamella hyaline with a thick red-brown pigmented secondary wall layer, the cells slightly longer than wide, the cavities (11)13–21(26) µm long × (6)7–9(10) µm wide. Oil-bodies of the lobe median cells (2) 3–5 (6) per cell, collectively occupying ca. 0.25–0.4 of cell cavity, subhyaline, surface appearing coarsely granular, the segmentation ± distinct, spherical, to 4.5 µm in diam., to ovoid or ellipsoidal, 4–8 µm long × 3–5 µm wide; of basal cells 5–7 per cell, becoming increasingly more botryoidal, and slightly larger.
Dioicous, ♂ and ♀ plants intermingledin same patch or found in different patches. Androeciasessile or nearly so, constituting a short lateral branch, androecium usually oblong spicate, or occasionally discoid, of (2–3)4–8(12) pairs of densely imbricate bracts, to 1000 µm long by 500 µm wide. Gynoecia terminal on short lateral branches (rarely terminal on main stem), ♀ Bracts and bracteoles in 2–3 pairs, grading to subfloral leaves; innermost bract unequally bilobed, lobe oblong to ovate with acute to narrowly rounded apices, lobe margin entire; lobule almost equal in length to lobe (but narrower), ca. 0.3 connate, lanceolate to falcate, acuminate at apex, ventral margins with 2–3 strong teeth near middle. Innermost bracteole free or connate with female bract on one side, 0.3 to 0.7 bilobed, lobes triangular-lanceolate, acuminate-subulate apex, laciniate at base. Median cells of bract penta-hexagonal, ± thin-walled but with strongly bulging nodulose trigones and intermediate thickenings extending toward centre of cell. 2 archegonia per gynoecium. Perianth half-exserted, to 1400 µm long × 800 µm wide, obovate-obpyriform, usually strongly 3-keeled (occasionally becoming plicate towards beakgiving the appearance of 1–2 extra minor keels on the ventral face), dorsal face ± convex, smooth, becoming retuse towards apex,perianth beak cylindrical from base to apex, often long (ca. one tenth in length of perianth). Median cells of perianth ± thin-walled but with strongly bulging nodulose trigones and intermediate thickenings extending toward the centre of the cell; cells penta-hexagonal.
Seta withc. 28–32 rows of epidermal cells + c. 8–12 rows of internal cells. Capsule valves 1030 µm long × 590 µm wide;epidermal cells with bulging thickenings at the cell corners, which extend over the face of the cell, and with thickenings along the longer walls; inner cell layer withthe thickenings appearing as a network-like configuration, the cell surface under the sem with fine perforations. Elaters68–78 per capsule, 200–250 µm long × 15–20 µm in diam., the surface under sem irregularly rugose-granulate. Spores globose, 35–45 µm at widest axis, which is interspersed with 8–10 rosettes; the rosettes each 3–4 µm in diam., and bearing a ring of 7–12 irregular, triangular, smooth projections, 0.5 µm wide at base and 0.5–1.5 µm in height (apices of longer projections are contiguous so that the centre of the rosette is mostly obscured); papillae otherwise densely distributed between rosettes. Spore diam./elater width ratio 7:3 to 9:4.
Affinities, differentiation & variation:
Frullaniaincumbens is morphologically similar to other species of subg. Australes, which include F. anomala Hodgs. and F. media (Hodgs.) Hatt. of New Zealand, and F. fugax (Tayl.) Tayl. from New Zealand and Australia. All taxa of subg. Australes share the following features: a campanulate lobule that is generally at least twice as long as wide and parallel or incumbent to the stem; lobule with wide-rounded apices and almost always constricted above the mouth; and the leaf-lobes with rounded to obtuse apices. Generally, Frullania incumbens can be distinguished from these species by the incumbent position of the lobules in relation to the stem. When fertile material with perianths is present, F. incumbens can immediately be differentiated from F. anomala and F. media. The perianths of F. incumbens are typically strongly 3-keeled and have a smooth surface. The perianths of F. anomala are also 3-keeled, but densely covered with multicellular projections, and the perianths of F. media also have a smooth surface, but are typically plicate with several keels.
Frullania fugax can be separated from F.incumbens by the following suite of features: plants of F. fugax are typically smaller, the lobules are narrower, to 2.5Χ long as wide and usually lie more or less parallel to the stem, and the lobes are often gemmiferous or caducous. The closest affinities of F. incumbens may lie with F. subincumbens Hatt. from Lord Howe Island, a species of subg. Australes where the incumbent form of the lobule is also present. Hattori (1987b) provided a suite of characters that distinguished F. subincumbens from F. incumbens, including the frequent presence of squarrose leaves and the scattered tuberculae on the perianth for F. subincumbens; 4-keeled perianth versus 3-keeled; short-beak versus long-beak; and only the dorsal lobe appendiculate versus appendiculate at both dorsal and ventral lobes. However, based on New Zealand specimens, F. incumbens shows morphological intergradation in some of the characters Hattori used to separate F. subincumbens from F. incumbens. Frullania subincumbens is only known from the holotype and more collections are required in order to confirm its taxonomic status and establish its relationship with other species of subg. Australes.
Geographic distribution & ecology: New Zealand, Australia (new report) [Tasmania, Australian Capital Territory, New South Wales] (Fig. 7.1).Corticolous or saxicolous favouring moderately shaded, well drained habitats in temperate forests and subalpine vegetation.A smaller Frullania species, F. rostrata¸ can frequently be found growing over or intermingled with the larger F. incumbens.
Notes: This taxon is a new record for Australia. Previously, F. incumbens was reported to be restricted to New Zealand (Hodgson 1949, Hattori 1983) where it is present in both the North and South Islands.