Isophyllaria E.A.Hodgs. & Allison
Isophyllaria E.A.Hodgs. & Allison in E.A.Hodgs., Trans. Roy. Soc. New Zealand, Bot. 3: 68. 1965.
Fulfordiella Hässel, Comun. Mus. Argent. Ci. Nat. “Bernardino Rivadavia,” Bot. 2: 48. 1974.
Type: Isophyllaria murrayana E.A.Hodgs. & Allison
Plants isophyllous (especially distally), rigid, fuscous to nearly black, rather small, 7–12 mm long, 0.5–1 mm wide with leaves. Branching irregular, sparing to rather frequent, mostly ventral-intercalary and leafy or stoloniform and whip-like, the stoloniform branches variable in position, in median as well as lower sectors of shoot; Frullania -type branches at times frequent; lateral-intercalary branches rare. Stem wiry, the cortex in surface view striolate, in cross section in 1 layer of ca. 20 rows of thick-walled cells larger than those of the medulla; medullary cell walls thin, thickened in the corners. Rhizoids from stem at underleaf bases, the tips branched. Leaves rigid, spreading, loosely imbricate, closely imbricate near shoot apices, unistratose, dorsally assurgent, the disc stiffly and widely spreading but the lobes incurved and forming a broad arch, the insertion transverse to weakly succubous, the leaves cuneiform, the base narrow, the leaves ± symmetric, bifid to 0.5–0.7, 400–450 µm wide × 650–1100 µm long; lobes subequal, divergent, often ± twisted, plane or weakly abaxially canaliculate (except at apices), tapered, lanceolate-acuminate, terminating in 1(2) cells or (ours) a uniseriate row of 2–4 ± isodiametric cells, the lobe margins entire; sinus ± rounded at base, the margin reflexed; disc obcuneate, entire. Cells evenly and distinctly thick-walled, the distal and marginal cells of lobes + marginal cells of disc ± isodiametric, the intramarginal cells wider and longer and forming a subvitta that extends into the lobe bases (the cells of the subvitta at most 2:1); median cells of disc 13–18 µm wide × 24–35 µm long; surface of lobes striate-papillose, of disc conspicuously long-striate. Oil-bodies dull and opaque, faintly greyish, 2–4 per median cell of lamina, obscurely and faintly coarsely granular, mostly globose and 2.5–4 µm in diam., less often broadly elliptic and 2.9 × 3.8–4.6 µm. Underleaves transversely inserted, similar in size and form to leaves or a little smaller. Asexual reproduction absent.
Dioecious. Androecia on long leafy shoots, becoming intercalary, the bracts in 2–7 pairs, subequal to leaves in size and basic form, contiguous to feebly imbricate, the disc sharply ventricose; antheridia 1–2 per bract, the stalk biseriate; bracteoles appressed to stem, smaller than bracts. Gynoecia with bracts and bracteoles similar in form to leaves and underleaves but larger, the lobes often twisted, with recurved margins, shallowly sulcate, the margins entire; coelocaule-precursor present, short, the bracts and bracteoles of 2 series becoming elevated on the coelocaule-precursor and inserted on it. Perianth exserted, linear-elliptic in outline, bluntly trigonous in distal half or a little more, weakly narrowed to the rather wide and open, at times slightly contracted mouth; mouth shortly dentate, the teeth comprised of a few cells.
Seta with an outer row of 16 cells surrounding an inner core of 9 or (Isophyllaria fuegiana) 17 somewhat smaller cells. Capsule spherical to short-cylindrical, in 3–4 layers; outer layer of cells with red or vinaceous nodular thickenings on longitudinal and transverse walls; innermost layer of cells with red or vinaceous nodular or sinuous-nodular thickenings, semiannular bands lacking.
Spores 12.5–16 µm in diam., red or red-brown, with vermiculate markings that often anastomose and some papillae (Isophyllaria attenuata), or densely granulate (I. fuegiana).
Elaters tortuous, bispiral throughout or bispiral in median sector and unispiral at the ends.
A genus with two closely related species, Isophyllaria attenuata and I. fuegiana (Hässel) R.M.Schust. of southern South America. Hässel (1974) described Fulfordiella fuegiana Hässel (type: Chile, Tierra del Fuego, Río Azopardo, 600 m, leg. Dusén), but later (Hässel, 1981) placed the species in the synonymy of I. attenuata, a plant described from Tasmania. Schuster (2000a) transferred F. fuegiana to Isophyllaria, and differentiated the Australasian populations by the transverse to weakly succubous leaves with lobes narrowly lanceolate and terminating in a uniseriate row of 2–4 cells vs. the transverse to weakly incubous leaf insertion and the narrowly or shortly acute leaf lobes that end in 1(2) cells in the southern South American I. fuegiana. Schuster (2000a) also differentiated the two species on branching: presence of Frullania -type branching in I. fuegiana vs. their absence in I. attenuata. However, terminal branches in the latter species are present and rather common, though less abundant than those of the ventral-intercalary type. Other characters found in I. fuegiana require further evaluation as they relate to I. attenuata. For example, I. attenuata has microphyllous shoots below ground (Hässel, 1981) vs. a more general distribution in the median as well as lower sectors of shoots in I. fuegiana.
References: Hodgson (1965); Hässel (1974, 1981); Schuster (1966a, 2000a).
