Radula anisotoma M.A.M.Renner, 2013

Renner, Matt A. M., Devos, Nicolas, Patino, Jairo, Brown, Elizabeth A., Orme, Andrew, Elgey, Michael, Wilson, Trevor C., Gray, Lindsey J. & Konrat, Matt J. von, 2013, Integrative taxonomy resolves the cryptic and pseudo-cryptic Radula buccinifera complex (Porellales, Jungermanniopsida), including two reinstated and five new species, PhytoKeys 27, pp. 1-113 : 19-21

Radula anisotoma M.A.M.Renner sp. nov. Figs 6 -7

Type:

Australia: Norfolk Island: Mount Pitt Reserve, Filmy Fern Trail, off Selwyn Pine Road, 29°01'S, 167°58'E, 130 m, 3 Dec 1984, H. Streimann 32084A, (holotype: CANB650459).

Diagnosis.

Within the Radula buccinifera complex Radula anisotoma is most similar to Radula strangulata by virtue of its small, rhomboid lobules whose apex lies close to or over the stem, and its leaf-lobes not interlocking over the dorsal stem surface, such that the stem is visible between leaves in dorsal view, and its habit of growing on rocks in association with waterways,but differs by its oblong leaf-lobes that are caducous, fragmenting into several irregular pieces, its narrower and longer female bract lobes, rhombic to trullate lobules and smaller stature.

Description.

[From CANB650459] Forming diffuse patches of small shoots, or mixed with other bryophytes, brown in herbarium; shoot systems monomorphic, irregularly branched, Lejeunea - type branching frequent, with additional pseudodichotomous branching due to production of subfloral innovations below gynoecia; 950-1280 mm wide and up to 20 mm long, branches initially smaller in stature than parent shoot, attaining similar stature to parent shoot after two or three leaf pairs; older shoot sectors denuded of leaf-lobes. Stems 90-150 µm diameter, with cortical cells in a single tier of 15-22 rows; cortical cell walls brown-pigmented; external free cortical cell wall continuously thickened, radial longitudinal cortical walls thin or slightly thickened, inner tangential walls discontinuously thickened; medulla cells in 12-20 rows, cell walls faintly yellow-pigmented or colourless, with small to medium-sized triangular trigones, walls between trigones unthickened. Cortical cells on dorsal stem surface arranged in straight longitudinal rows on young and mature shoot sectors. Leaf insertion not reaching dorsal stem mid-line, leaving one or two dorsal cortical cell rows leaf-free, dorsal leaf-free strip present; leaf insertion not attaining the ventral stem mid-line, leaving two ventral cortical cell rows leaf-free. Leaf lobes oblong-elliptic, 380-710 µm long by 300-490 μm wide, contiguous, not falcate, acroscopic base lying in plane with stem, plane, not interlocking over the dorsal stem surface, stem visible between leaf lobes in dorsal view; margins irregularly repand, marginal cells bulging, the interior lobe margin not or only weakly ampliate, not or hardly riding onto dorsal stem surface, antical margin curved, exterior margin sharply curved through nearly 100°, postical margin straight; angle between postical lobe margin and keel c. 135°. Lobules rhomboid, remote, one tenth to one eighth the lobe area, 140-350 µm long by 105-240 μm wide; keel straight or rarely slightly arched, angle between keel and stem 135°, keel apex and postical lobe margin flush; interior lobule margin free for one third to one half its length, free portion not or weakly ampliate, hardly riding onto ventral stem surface, not concealing the stem in ventral view; acroscopic margin straight or curved; inclined inwards toward the stem; apex acute, laying close to or over the stem margin, free exterior margin straight to weakly curved, margins irregular; lobe-lobule junction level with or slightly postical to the acroscopic end of stem insertion; attached to stem along 0.5-0.33 of the interior margin, stem insertion more or less linear, gently curved at acroscopic and basiscopic ends, not revolute; lobule apex bearing a single papilla, with another two papilla situated on the interior lobule margin above the stem insertion. Leaf lobe cells rounded, not arranged in rows, unequally sized, 9-24 µm long by 9-19 μm wide, thin walled with concave trigones, medial wall thickenings absent; cells of lobe margin smaller than those of leaf middle, quadrate to rectangular, 9-14 µm long and wide, interior and exterior cell walls not differentially thickened; leaf lobe cell surface smooth. Oil-bodies not known. Asexual reproduction by caducous leaf lobes, fragmenting into several irregular pieces, marginal lobe cells often proliferating to form bud-like shoot primordial. Dioicous. Androecia not known. Gynoecia terminal on branch shoots, subtended by 2 or 3 subfloral innovations that are the same size as the branch shoot and are again fertile; archegonia 115-130 µm tall, archegonial neck 6 cell columns; 14-15 per gynoecium on a small disc of tissue, encompassed by the protoperianth; female bracts in one or one and a half pairs, symmetrical, imbricate, narrow oblong-elliptic, lobe 655-975 μm long by 265-450 μm wide, margins entire or repand; lobules rhomboid to trullate, one fifth to one quarter the lobe area, apex obtuse to acute, not or shallowly notched, keel arched, margins irregular; bract insertion lines interlocking dorsally and ventrally, insertion equitant. Perianths c. 3100 µm long and 660 µm wide at mouth, mouth repand, more or less parallel sided for upper third, then tapering to tubular stem perigynium comprising the lower third to half, broadest at mouth, walls 2- or 3-stratose at junction with perigynium, unistratose above. Long stem perigynium present, multi-stratose throughout. Calyptral perigynium present.

Etymology.

From Greek an (αν-): not, isos (ισοσ): even, tomos (τοµος, m.): slice, piece - uneven slice, in reference to the caducous leaf lobes that fragment into uneven pieces.

Distribution and ecology.

Radula anisotoma is currently known only from Norfolk Island where, at the only known location, it occurred in dense forest at 130 m within Mt Pitt Reserve. The plants grew beside a creek, presumably within a gully, on a rock admixed with Lejeunea anisophylla Mont., Metzgeria sp. and Radula cf. novae-hollandiae (see comments below under Radula farmeri Pearson for explanation).

Recognition.

Identification of Radula anisotoma should present no difficulty. The most accessible morphological character of Radula anisotoma that differs from all other members of the Radula buccinifera complex is the production of caducous leaves and associated proliferation of marginal lobe cells to form bud-like shoot primordial. Caducous leaves are not produced by any other member of the Radula buccinifera complex, with the exception of Radula mittenii which differs in a number of macro- and micro-morphological characters, and bud-like shoot primordia have only been observed twice, on two different specimens of Radula strangulata (M.A.M. Renner pers. obs.).

Radula anisotoma is most similar to Radula strangulata and, notwithstanding the differences described above, could be confused with that species. However, there are several subtle differences between Radula anisotoma and Radula strangulata in the shape of leaf lobes, lobules, and female bracts, which will aid identification. The leaf lobes of Radula anisotoma are oblong, whereas they are round in Radula strangulata . The lobules of Radula anisotoma are rhombic to trullate, whereas they are rhombic to longitudinally rectangular in Radula strangulata . The female bract lobes are narrowly oblong in Radula anisotoma , whereas they are elliptic-ovate in Radula strangulata . Finally, Radula anisotoma is generally a smaller plant than Radula strangulata . Comparison with known material is recommended in order to appreciate the degree of difference in shape between, as well as variation within, each species when making determinations.

Specimens examined.

Australia: Norfolk Island: Mount Pitt Reserve, Filmy Fern Trail, off Selwyn Pine Road, 29°1.3'S, 167°57.6'E, 130 m, 3 Dec 1984, H. Streimann 32078 (CANB650457, NICH, NY, EGR, H); ibid. H. Streimann 32083, CANB650458.

Figures

Figure 6. Radula anisotoma line drawings A Dorsal shoot B Ventral shoot C Archegonia D Ten haphazardly selected lobules, showing size and shape variation E Lobule showing cellular detail F Cells of leaf lobe margin showing initiation of shoot primordia G Medial leaf-lobe cells H Marginal leaf-lobe cells I Female bract showing narrow elliptical lobe J Stem transverse section K Dorsal stem surface showing leaf-free dorsal cortical cell rows L Ventral stem surface. Scale bars: A-B: 600 µm, C, F: 40 µm, D, I: 240 µm, E, G, H, J-L: 60 µm. All from CANB 650459.

Figure 7. Radula anisotoma pictures A Ventral view of shoot B Mature perianth. C-E Ventral view of shoots and lobules F Gynoecium G Androecium H-I Transverse sections of stems from primary shoot J Leaf-lobe marginal cells. All from CANB 650459.