Radula pugioniformis 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 : 55-57

Radula pugioniformis M.A.M.Renner sp. nov. Figs 25 -27

Diagnosis.

Radula pugioniformis is outwardly similar to Radula buccinifera , but can distinguished by the presence of three female bracts in association with the gynoecium, the trullate to pugioniform lobules, the stem anatomy, where the cortical cell walls are heavily and continuously thickened which partially constricts the cell lumen, and the medulla cell walls are also continuously and heavily thickened, somewhat more so at cell junctions.

Type.

Australia: New South Wales: Central Tablelands, Small gully near Wonga Falls on Lamonds Creek, Barren Ground Nature Reserve, 34°41'S, 150°43'E, 500 m, 22 April 1992, R.G. Coveny 16096 & P.D. Hind, (holotype: Element 1 within NSW770504, with a portion separated in a subpacket).

Description.

[From NSW770504] Forming loosely interwoven mats of adherent shoots on soil and rock; live plants unknown, brown in herbarium; shoot systems monomorphic, 1.0-1.5 mm wide and up to 40 mm long, irregularly branched, though female plants predominantly pseudodichotomous due to production of pairs of subfloral innovations below gynoecia, branches initially smaller in stature than parent shoot but attaining similar stature to parent shoot by second or third pair of leaves; older shoot sectors retaining leaf-lobes. Stems 110-140 µm diameter, with cortical cells in a single tier of 19-25 rows, cortical cell walls yellow-brown pigmented, all walls heavily and continuously thickened, partially constricting individual cell lumen; medullar cells in 12-17 rows, medulla cell walls yellow-pigmented, continuously and heavily thickened, somewhat more so at cell junctions; cortical cells on dorsal stem surface arranged in straight longitudinal row on young and mature shoot sectors. Leaf insertion not reaching dorsal stem mid-line, leaving one to three dorsal cortical cell rows leaf-free; leaf insertion not attaining the ventral stem mid-line, leaving four or five ventral cortical cell row leaf-free. Leaf lobes ovate, 620-860 µm long by 500-700 μm wide, imbricate, weakly falcate or not, acroscopic base plane, not sharply deflexed away from stem, not interlocking over the dorsal stem surface, stem visible between leaf lobes in dorsal view, margins entire, the interior lobe margin weakly ampliate, not auriculate, not or only just reaching the opposite stem margin, more or less straight in larger lobes, sometimes with a single triangular tooth near the stem insertion, more often in smaller lobes, antical margin continuously curved, exterior margin curved, postical margin straight or slightly curved; angle between postical lobe margin and keel 100-135°. Lobules rhombic to trullate, one eighth to one seventh the lobe area, 240-485 µm long by 185-310 μm wide, keel slightly curved or straight, angle between keel and stem 100-135°, keel apex and postical lobe margin weakly notched, inner lobule margin free for one half to two thirds its length, free portion not ampliate, not extending across stem beyond insertion line, acroscopic margin straight to weakly curved, apex narrowly rounded to acute, free exterior margin straight, occasionally with a small knee above the lobe-lobule junction, margins plane, entire; lobe-lobule junction postical to the acroscopic end of stem insertion, attached to stem along 0.33-0.5 of the interior margin, stem insertion gently curved its entire length, not revolute; lobule apex bearing a single papilla, no other papilla, or papilla scars, observed on the interior lobule margin. Leaf lobe cells hexagonal-oblong, not arranged in rows, unequally sized, 11-21 µm long by 10-12 μm wide, walls moderately and continuously thickened. Cells of lobe margin smaller than those of leaf middle, quadrate to rectangular, 6-12 µm long by 6-10 µm wide, interior cell walls evenly and continuously thickened, exterior cell wall unthickened. Leaf lobe cell surface unornamented, smooth. Oil-bodies not known. Asexual reproduction absent. Dioicous. Androecia on short lateral branches or terminal on leading shoots, either terminating following androecia production, or continuing vegetative growth; antheridial bracts in 3-4 pairs; lobules epistatic, keel deeply curved, bucket-like, free apical portion triangular, apex acute, plane, lobes rounded, not caducous; antheridia not seen. Gynoecia terminal on leading shoots and branches, subtended by one or two full sized subfloral innovations that are again fertile, more often subtended by a single subfloral innovations on branches with a ‘resting’ shoot primordium in place of the second subfloral innovation. Archegonia 175-190 µm tall, archegonia neck five or six cell columns, 12-14 per gynoecium on a small raised disc of tissue, encompassed by the protoperianth, with several large single celled or stalked (on 2 or 3 cells) papillae scattered among gynoecia. Female bracts three, symmetrical, imbricate, obovate-falcate, lobe 1140-1255 μm long by 670-795 μm wide, lobules triangular, one half the lobe area, 585-930 μm long by 340-645 μm wide apex acute, keel arched, margins entire, insertion interlocking dorsally and ventrally, insertion equitant. Perianths and sporophytes not known.

Etymology.

From Latin Pugioniformis , with the form of a dagger, in reference to the resemblance of the lobules to broadly triangular iron daggers adopted by several ancient cultures, including in the Roman Empire as the ‘Pugio’.

Distribution and ecology.

Radula pugioniformis is known from a range of localities in the Central and Southern Tablelands of New South Wales. The two specimens with details on substrate indicate Radula pugioniformis grows on wet mud and rocks in and around streams or other watersources, in gullies or on steep slopes. Radula pugioniformis has been collected growing with Radula buccinifera , Acrophyllum dentatum , Thuidium furfurosum , and Bryum sp. on soil, and with Lejeunea sp. on rock.

Variation.

Within individuals, shoot stature varies, and this is correlated with changes in lobule shape, which tend to be shorter on smaller shoots.

Recognition.

Radula pugioniformis is outwardly similar to Radula buccinifera , and inhabits a subset of microhabitats occupied by that species. Differentiating these two species is best achieved on the basis of hydrated, and preferably slide mounted material. The most accessible character by which Radula pugioniformis and Radula buccinifera differ is in shape of the leaf lobules. In Radula pugioniformis the lobules are conspicuously trullate, the antical margin is straight to curved, and slopes steeply toward the stem at 45-70°, such that the lobule apex lies well above the antical end of the stem insertion. In Radula buccinifera the lobules are quadrate to rhombic, the lobule apex lies at variably between the same level as, or slightly above, the uppermost point of the ampliate portion of the lobule margin. Between these two points the lobule margin varies from straight to S-shaped in situ (straight when flattened), but when S-Shaped there is a pronounced medial curve. The slope of the antical margin varies between sloping downward toward the stem at up to 45° and remaining level.

Other diagnostic differences between Radula pugioniformis and Radula buccinifera can be found in the stem anatomy. In Radula pugioniformis the cortical cell walls are heavily and continuously thickened, which partially constricts the cell lumen, and the medulla cell walls are continuously and heavily thickened, somewhat more so at cell junctions. In Radula buccinifera the free external cortical cell wall is differentially thickened, but all other cortical and medulla cell walls bear triangular trigones at most, and are otherwise unthickened.

Radula pugioniformis is similar to Radula iwatsukiana K.Yamada from New Caledonia, and may be related to this species. However, the type of Radula iwatsukiana was not available for study due to CITES restrictions, and interpretation of morphology via descriptions and illustrations is fallible. The size of female bracts in both absolute terms and relative to vegetative leaves differs in Radula pugioniformis from that described and illustrated by Yamada (1985), the illustrations also suggest a sharp distinction between marginal and medial cells in Radula iwatsukiana that does not occur in Radula pugioniformis . If Yamada’s illustration is representative of Radula iwatsukiana , there are also differences in the relative sizes of cortical and medulla cells in the stem; in Radula iwatsukiana these are approximately the same area in transverse section, while in Radula pugioniformis the cortical cells are half to one quarter the area of the medulla cells. They are also far more numerous.

Remarks.

Female bract number suggests this species belongs to subg. Odontoradula , not subg. Metaradula . Although apparently not closely related to species of the Radula buccinifera complex, Radula pugioniformis is included here because it has been misidentified as Radula buccinifera .

Specimens examined.

New South Wales, Southern Tablelands, Tumbarumba District, November 1900, W. Forsyth, NSW764133; ibid, H228, NSW; Southern Tablelands, slopes of Mt Buddawang, near Mongarlowe, 28 October 1965, L.G. Adams 1427, NSW764186.

Figures

Figure 25. Radula pugioniformis line drawings 1. A Dorsal view of shoot B Ventral view of shoot C Detail of lobule interior free margin D Five lobules from secondary shoots showing variation in size and shape E Detail of lobule apex F Five lobules from primary shoots showing variation in size and shape. Scale bars: A-B: 600 µm. C, E: 60 µm. D, F: 240 µm. All from NSW 770504.

Figure 27. Radula pugioniformis pictures. A Ventral view of shoot. B-E: Ventral view of lobules on primary shoots F Gynoecium G Androecium H Transverse sections of stems from primary shoot I Leaf-lobe marginal cells. All from NSW 770504.