Plants usually small to medium(main shoots 500–1100 µm wide), forming olive-green to reddish brown patches, closely to loosely adhering to substrate. Leading stem 10–20 mm long and 125–175 µm in diam., (7)8–10(11) cells wide; 15–25 cortical cells + 15–30 medullary cells, cortical cells occasionally slightly smaller than medullary cells, otherwise little differentiation between them,both cortical and medullary cells with heavily thickened, subhyaline to pale yellow walls, lumen irregularly shaped. Branching often irregularly pinnate, occasionally 2-pinnate, elongate and similar to main stem, of Frullania-type. First branch underleaf (BUL1) usually with two distinct segments, 1 large unlobed ventral segment (to 400 µm long) + 1 smaller dorsal segment (to 225 µm long); occasionally BUL1 with three distinct segments, 1 ventral bilobed + 1dorsal, explanate to at most sulcate segment. Stemleavesof main branchflat when dry and wet, imbricate to occasionally contiguous, (220)300–720(800) µm long ×(180)250–600(750) µm wide, obovate to suborbicular, often with strongly incurved apices, dorsal margin extending beyond the farther edge of the stem (0.25–1Χ the stem width), apices rounded to obtuse, dorsal base arched and strongly auriculate to ligulate at the base; surface smooth; margins entire. Lobules variable, though phenotypes with explanate or sulcate lobules are rare except when the lobules are situated near ♂ or ♀ gametangia, usually the lobules are well developed, ± inflated throughout and comparatively large (often 0.5 to 0.75Χ the exposed area of the associated leaf-lobe, almost similar in size to stem underleaf), the lobules often galeate and ± as long as wide or occasionally slightly longer than wide, occasionally oblate, (130)170–550(620) µm long × (120)130–440(510) µm wide, the lobule to 35 cells in circumference at broadest region, a developed beak often present but short and apiculate at the apex, the free margin of lobular mouth truncate or slightly arched, to 15 cells in length, the lobule apex broadly rounded. Stylus almost always medium to large in size, foliose, lanceolate-triangular, (80)100–210(250) µm long × 50–100 µm wide, broadest at or just above base where the stylus is (3)4–5(7) cells wide, attenuate and rounded at the apex, often terminating in row of 3–4 uniseriate cells, (6)8–26(30) cells in total, slime papilla at apex uncommon.Underleaves of leading stems small to medium in size (ca. 0.25–0.5 the size of leaf lobes), flat and closely appressed to stem, slightly contiguous to and rarely overlapping with lobules, underleaves usually distant from each other, usually slightly longer than wide (occasionally 1.5Χ long as wide), obcuneate with straight lower margins, usually forming a triangular tooth at shoulder; some phenotypes occasionally suborbicular to rectangular in outline, with entire margins, (150)220–600(650) µm long× (125)180–480(540) µm wide, broadest above middle (to 30 cells wide); apex of underleaf bilobed 0.25–0.35 its length, lobes separated by a narrowly U to V-shaped sinus, lobes triangular with subacute to narrowly obtuse apices; insertion transverse. Rhizoid-initial area ranges from just below underleaf sinus or near middle to base of underleaf, rhizoids infrequent, fasciculate, brown pigmented, to 320 µm long. Plants not microphyllous, organs of secondary branches similar in size to those of the main stem.
Lobe median cells with weakly to strongly sinuose walls, subtriangular to confluent trigones and occasional ± nodulose intermediate thickenings, hyaline along the middle lamellae, and usually with dark reddish-brown pigmented secondary thickening, the cell cavities brownish red, (14)16–25(28) µm long × (12)14–20(25) µm wide, becoming gradually larger basally; basal cells with ± thin, straight to sinuose walls with large trigones, intermediate thickenings rare, the cavities of the basal median group of cells (24)30–44(49) µm long × (20)25–36(40) µm wide; marginal cells with hyaline, weakly sinuose, ± equally thickened walls, cells ± rectangular to irregular, cavities brownish red, 10–16 µm long × 8–16 µm wide. Underleaf median cells with sinuose walls ± equally thickened due to confluent trigones and intermediate thickenings, the cell cavities 16–28 µm long × 12–23 µm wide. Lobulemedian cells with strongly sinuose walls and with indistinct trigones and nodulose intermediate thickenings, cells slightly longer than wide, the cavities 14–20 µm long × 8–12 µm wide. Asexual reproduction: none reported.
Dioicous. ♂ Plants often slightly smaller (shoots to 600 µm wide) than ♀ plants. Androecia discoid (600 µm long × 500 µm wide) to spicate (1050 µm long × 600 µm wide), 3–10(12) pairs of bracts, sessile or terminal on very short-stalked branches (stalk with 1–2, rarely 3 modified vegetative leaf lobes). Gynoecia terminal on main stem and branches, often bearing 1 subfloral innovation, developing in place of the outermost bract-lobule below the ♀gynoecium. Bracts and bracteoles in 2–3 pairs grading to modified leaves. Innermost bract unequally bifid; bract-lobe elliptical to ovate, becoming narrowed toward a rounded apex, the margin entire; bract-lobule ± lanceolate, 0.35–0.5 connate with bract-lobe, attenuate to subacute at the apex; margin entire except for a large spinose tooth (to 250 µm long) at the base of the free margin. Innermost bracteole ± oblong in outline, ca. 0.2–0.25 bilobed, the sinus acute and often narrow, lobes narrowly triangular and attenuate towards apex terminating in a uniseriate row of (2)3–5(6) cells. Two or three archegonia per gynoecium. Perianth freely emergent, often ± oblong, usually longer than wide (900)1000–1800(1850) µm long × (625)700–950(1100) µm wide, tapering abruptly towards the apex, usually into a long beak; perianth beak cylindrical, to 200 µm long × 80 µm, with a smooth mouth and inner beak surface; mulitplicate, 2 ± large lateral keels + 2–3 dorsal keels + 3–4 (5) ventral keels; thus 7–10 keeled in transverse profile; keels usually occurring from perianth base to apex; margins of keels strongly crispate, inflated, and rounded; irregular and shallow tubercles or projections often present on keels and less often on the intervening surfaces. Median cells of perianth with ± thin, semi-straight walls and large bulging convex trigones, intermediate thickenings usually absent. In some phenotypes walls occasionally becoming sinuose with large confluent ± subnodulose trigones and intermediate thickenings; cell cavities to 25 µm long × 20 µm wide.
Capsule valves to 750 µm long × 450 µm wide; inner cell layer withthe thickenings appearing as a network-like configuration across the face, ridges along the individual cells inconspicuous to absent, the cell surface under sem appearing ± smooth, without any ornamentation. Elaters to 80or more in total (arranged in 5–6 rows), the surface under sem irregularly rugose-granulate. Spores globose, to 40 µm at widest axis, which is interspersed with 7–9 rosettes. The rosettes each 4–6 µm in diam. and bearing a ring of (4)6–8(9) irregular, elongate protuberances; these protuberances ± smooth, usually baculate, ca. 1.5–1.75Χ long as wide (to 2 µm long × 1.75 µm wide), occasionally only 1Χ long as wide (to 1 µm long × 1 µm wide), longer projections occasionally tapering to a hook-like apex; the spore wall papillae otherwise densely distributed between rosettes.
Affinities, differentiation & variation:
Hattori (1983) implied a close relationship between F. probosciphora and the New Zealand taxon F. reptans, stating that the latter may be a geographical race of the former. The relationship between these two taxa is under investigation. There is also obvious morphological affinity with F. pentapleura; Table 7.5 lists many features that the species have in common as well as those features, which help distinguish between the two species. Noteworthy is the fact that based on herbarium annotations; F. probosciphora is often confused with some species of subg. Australes,e.g., F. fugax and F. incumbens. The typical features of this subgenus are discussed elsewhere in this paper under F. incumbens. Two key features, both associated with the lobule, help distinguish F. probosciphora from members of subg. Australes. (1) The lobule of F. probosciphora is typically as long as wide or occasionally c. 1.5Χ as long as wide. In contrast, the lobule of species of subg. Australes is typically at least c. 2Χ long as wide. (2) The lobule is very wide at the mouth in F. probosciphora and is not strongly constricted above the mouth. In contrast, the lobule of species of subg. Australes is typically constricted above the mouth, with the free outer and inner margins developed into a small beak.
Geographic distribution: Frullania probosciphora is distributed throughout Tasmania and is also found in southwestern Australia (Victoria and New South Wales), and New Zealand. Plants in these regions are both corticolous and saxicolous and grow in exposed and semi-shaded habitats.
Notes: Hattori (1979a) reduced F. falsa Steph. to a synonym of F. probosciphora. Later, Hattori (1988) reduced F. probosciphora to a subspecies of F. pentapleura and developed a new combination, F. pentapleura subsp. falsa. However, the evidence presented above shows that there are sufficient differences between F. pentapleura and F. probosciphora to maintain them as distinct at the species level.