Jamesoniella tasmanica (Hook.f. & Taylor) Steph.
Jungermannia tasmanica Hook.f. & Taylor in Taylor, London J. Bot. 5: 274. 1846.
Mesophylla tasmanica (Hook.f. & Taylor) Trevis., Mem. Reale Ist. Lombardo Sci. Lett. III, 4: 398. 1877.
Jamesoniella tasmanica (Hook.f. & Taylor) Steph., Sp. Hepat. 2: 100. 1901.
Type: Tasmania, Gunn.
Jamesoniella cambewarrana Steph., Sp. Hepat. 6: 97. 1917.
Type: Australia, Cambewarra, Watts; New Zealand, Great Barrier Is., Hooker (cf. Grolle, 1971a).
[Plate 14F; Fig. 156; Fig. 158: 2, oil-bodies, p. 724]
Plants distinctly plagiochiloid in aspect, procumbent and firmly adhering to the substrate, the shoot tips very weakly ascending, the plants green or tinged with claret red, at times ± intensely red, to 4 mm wide. Stems thick, fleshy, colorless or rarely weakly reddish, the cortical cells in 1–2 layers, somewhat smaller, their walls somewhat more strongly thickened; medullary cells colorless, thin-walled. Rhizoids from ventral side of stem, extending almost to shoot apex. Branching infrequent, of terminal, Frullania type; half-leaf ovate, longitudinally inserted; first branch underleaf narrowly elliptic, at base of branch, entire or bifid (at times asymmetrically) almost to base; leading, leafy ventral-intercalary branches present; stolons lacking. Leaves horizontally spreading (at least distally) to strongly dorsally elevated, distinctly convex (in dorsal aspect), the margins ± broadly reflexed, the median basal portion of the leaf typically concave, somewhat hollowed out and laxly sheathing, the insertion steeply oblique in dorsal portion, becoming subtransverse, abruptly short-recurved at ventral end, the attachment equal to 0.65–0.75 the leaf width; leaves (when flattened) ovate to elliptic-ovate, 1250–2000 µm wide × 1600–1800 µm long, entire; apex rounded to weakly truncate, at times retuse to shallowly bifid; dorsal margin usually short-decurrent; ventral margin moderately decurrent (at times more so on one side of the shoot). Cells evenly thick-walled, but in median optical section appearing thin-walled and with small to medium and straight-sided trigones; cells of upper median portion of leaf 20–30 × 25–35 µm; cells toward the median-leaf base gradually enlarged; surface smooth or closely and finely striate, especially at base of leaf. Oil-bodies occupying a large proportion of the cell, hyaline and glistening, 16–20 per median leaf cell, moderately papillose, the spherules slightly protruding beyond the membrane, the oil-bodies irregular in shape: subglobose to broadly ovoid to broadly elliptic, a few sublinear, 4.8–5.3 × 5.3–6.2 µm to 3.8–4.8 × 7.2–8.2 µm, some 3.4 × 6.7 µm, sporadic ones large and 4.3–4.8 × 9.6–10.6 µm. Underleaves highly variable, minute, subulate, or at times larger and narrowly elliptic, rarely deeply bifid, usually united on one side with a leaf, on the opposite side decurrent or sometimes fused with the leaf opposite by a transverse ridge, the ridge with a minute apiculus representing the underleaf.
Androecia on leading shoots, not much narrower than vegetative sectors, with up to 12 pairs of bracts; bracts strongly saccate in basal portion, the dorsal margin of the bract decurrent as a broad abaxial wing (the lobule thus seemingly inserted on the adaxial face of the bract); lobule broadly lanceolate, the apex apiculate to acuminate, the free margin with 1–2 small teeth; antheridia solitary, the stalk biseriate. Gynoecia mostly innovating, notable when young and without a distinct perianth as a laciniate bud; bracts increasing in size toward perianth, those of innermost series markedly smaller, free from one another, one or both bracts of innermost series strongly laciniate-lobulate (fundamentally bilobed, with several accessory lobules and teeth); bracteole free, nearly equal to bracts in length, basically bilobed, at times with several accessory lobes, the margins with 1 or more teeth. Perianth elliptic to obovate, strongly plicate in the upper 0.25–0.35, strongly contracted to the truncate mouth, the mouth shallowly lobulate, finely and irregularly denticulate by wholly or partially excurrent elongated cells; cells of lobules elongated, the cells below subisodiametric; perianth 2-stratose in basal 0.5.
Capsule ellipsoidal, the wall 5–6-stratose; outer layer of cells with the radial longitudinal walls with nodular thickenings, the transverse walls rarely with isolated nodular thickenings; innermost layer of cells with thickened longitudinal walls, with semiannular bands common, rather narrow, complete or tapering to a sharp point before reaching the opposite wall, sometimes forked but not anastomosing.
Spores 18–19 µm in diam., with fine papillae and short-vermiculate ridges. Elaters bispiral, 8–11 µm wide.
Distribution and Ecology : New Zealand: Auckland Islands (30 m), Stewart Island, South Island (50–720 m), North Island (100–760 m); Australia: Tasmania, Victoria, South Australia, New South Wales. In New Zealand known from Fiordland, Otago (Mt. Cargill, Lakes region), Canterbury (Mt. Cook Natl. Park), Westland, Western Nelson, Sounds–Nelson, Taranaki, Volcanic Plateau, Gisborne and Northland EPs.
The species is for the most part a lowland forest plant of Nothofagus fusca, N. menziesii, N. solandri, Knightia excelsa, Weinmannia racemosa and N. truncata forests, and typically occurs below 600 m. The species is not a pioneer, but rather grows in bryophyte-rich associations. It occurs on the forest floor, on bryophyte-covered banks, and, rather commonly, on old, rotted, bryophyte-covered, decorticated logs and at the bases of tree trunks and stumps. The species occasionally grows in open boggy areas with, for example, Coprosma spp., Juncus squarrosus, Leptospermum scoparium and Ozothamnus leptophyllus (Saddle W of road to Mt. Cargill, N of Dunedin, 500 m), and in Westland it has been found on soil in pakihi. It exceptionally occurs on rock, e.g., at the summit area of Haast Pass (510–560 m, Mt. Aspiring Natl. Park) it formed pure, thick, cushion-like masses over the side of a boulder. It occurs with Bazzania adnexa, Chiloscyphus mittenianus, Cuspidatula monodon, Heteroscyphus cymbaliferus, Hymenophyton flabellatum, Hypnum chrysogaster, Lepidozia pendulina, Leptophyllopsis laxus, Leucobryum candidum, Pyrrhobryum bifarium and Rhizogonium pennatum.
Comments : Jamesoniella tasmanica is distinctly Plagiochila -like in aspect (in particular, P. banksiana): the plants are soft-textured, with distinctly convex, horizontally spreading ovate to elliptic-ovate leaves, with broadly reflexed margins and a hollowed-out median basal portion (Fig. 156: 1–3).
The underleaves of Jamesoniella tasmanica are the best developed of any regional species of the genus, but there is considerable variation in underleaf form, even along the length of a single shoot. At one extreme, the underleaves are narrowly elliptic (rarely deeply bifid, and still more rarely free), but in the main the underleaves are represented by a small triangular to subulate process, basally united with the ventral margin of an adjacent leaf (Fig. 156: 5). In the absence of evident underleaves, there is often a low, arched ridge united to at least one (Fig. 156: 5, lower), and rarely both leaves, with the underleaf represented only a minute sharp tooth on the ridge.
The androecia of Jamesoniella tasmanica are notable for the strongly winged bracts, the lobules seemingly inserted on the adaxial face of the bract (Fig. 156: 8). The apex of the lobule is sharply acuminate and usually conspicuous even under the dissecting microscope.
