Plants small to medium, main shoots ca. 500–900 µm wide. Branching of Frullania-type and occasionally of Lejeunea-type. Initial branching appendages of the Incumbens-type, including only two segments at BUL1, of unequal length, the ventral segment to 150 (220) µm long. Main leaflobes various, ±contiguous to slightly sub-remote on main stems, occasionally distant, 500 µm long × 350 µm wide, distal margins typically flat or only incurved, with widely obtuse to rounded apices, base cordate, usually only the antical base ± auriculate-appendiculate. Lobules of the main stem typically subparallel to the stem or less commonly incumbent with apices slightly–strongly inclined toward the stem, lobuli typically distant to sub remote, occasionally contiguous or slightly imbricate, lobule size and shape various, but typically ± long, narrowly campanulate, (1.25) 1.5–2.25 (2.5) Χ long as wide, to 325 µm long × 200 µm wide; lobuli with curved to subparallel sides with wide rounded apices, slightly constricted above the mouth; lobules of lateral branches occasionally weakly incumbent and partially imbricate to each other, and often slightly more elongated. Underleaves of leading stems to 250 µm long × 175 µm wide (to 375 µm long × 250 µm wide for elaborately toothed phenotypes) rhombic-obovate to broadly cuneate narrowed towards the base, narrow, transverse insertion, lateral margins various, either entire, obtusely to subacutely dentate of 2–7 cells, or bluntly angular; underleaf 0.3–0.5 bilobed by a narrow slit to U-shaped sinus.
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 hyaline with a thick red-brown pigmented secondary wall layer, the cells to 15–20 (25) µm long × 10–15 µm wide, the cells becoming gradually larger basally; lobe basal group of cells with large subnodulose trigones and thin intervening walls, and rarely with nodulose intermediate thickenings. Underleaf and lobule median cells with strongly sinuous walls. Asexual reproduction common, via gemmae and propagula, variously produced on organs throughout plant, including both dorsal and marginal tissue. Oil-bodies of the lobe median cells (2) 3–4 (5,6) per cell, collectively occupying ca. 0.2–0.4 of cell lumen, subhyaline, surface appearing coarsely granular, the segmentation ± distinct, spherical, to 3.5 µm in diam., to ovoid or ellipsoidal, 4–10 µm long × 3– 4 µm wide; of basal cells 4–7 per cell, becoming increasingly more botryoidal, and slightly larger.
Gynoecia terminal on main stem or leading branches, often branching immediately below the gynoecia, ♀ Bracts and bracteoles in 2–3 pairs, grading to subfloral leaves; innermost bract unequally bilobed, lobe oblong to ovate to 650 µm long, with rounded to subacute apices, lobe margin entire; lobule almost equal in length to lobe (but narrower), ca. 0.3 connate, lanceolate, acuminate toward apiculate-acute apex, ventral margins of both lobes with 1 large, acuminate tooth near middle, to 175 µm long. Innermost bracteole to 0.7 bilobed, lobes triangular-lanceolate, acuminate apex. Perianth ± half-exserted, small to medium, to 1000 µm long × 800 µm wide, obovate-obpyriform, typically strongly 3-keeled, with 2 broad lateral keels + 1 broad ventral keel, and occasionally minor, 1–3 accessory keels, or becoming plicate towards the perianth apex and becoming retuse;surface smooth, occasionally with crispate keels; perianth beak cylindrical from base to apex, often long (to 1/10th in length of perianth) to 150 µm long.
Affinities: In New Zealand, Frullania fugax appears morphologically similar to F. media and is discussed under that species. Previously, Hattori (1979b, 1987b) stated that this species seems most closely related to F. yorkiana Steph. However, Frullania yorkiana is one of several species, including F. baileyana, F. belmorensis, F. cataractama, which are only known from the type collections or the sterile state. With further collections, all of these species may yet prove to be conspecific with F. fugax, and are listed under dubious species at the conclusion of this treatment. Certainly, at least from the scant material available of the type specimens, the gametophytes appear to be very similar. However, in the absence of further collections, particularly of the perianths it is difficult to arrive at any formal conclusions.
Geographic distribution & ecology:
Distributed throughout Australasia (Fig. 7.1), including throughout the New Zealand botanical region. Of the New Zealand species, F. fugax is common on rotting wood or logs and is commonly found with gemmae or propagula.
Notes: Frullania fulfordiae is reduced to a synonym of F. fugax because all of the salient characters used to recognise it such as the toothed lateral margin of the stem underleaf are present in F. fugax, and there appears to be no correlation with geography or any other characters.