Solenostoma orbiculatum (Colenso) R.M.Schust.
Gymnomitrion orbiculatum Colenso, Trans. & Proc. New Zealand Inst. 18: 236. 1886 (“Gymnomitrium orbiculata”). Jungermannia orbiculata (Colenso) Grolle, J. Jap. Bot. 4: 144. 1966, non J. orbiculata (Amakawa) Amakawa, J. Hattori Bot. Lab. 30: 188. 1967 (= J. suborbiculata Amakawa). Solenostoma orbiculatum (Colenso) R.M.Schust., Beih. Nova Hedwigia 119: 380. 2002. Lectotype (fide Váňa, 1975): New Zealand, Waipawa Co., near Norsewood, Mangatawhainui River, Oct. 1884, Colenso (WELT, non vidi); probable isolectotype: (MPN, hb. Hodgson no. 13679, non vidi).
Jungermannia fragilis Gottsche, Linnaea 28: 551. 1857, non J. fragilis Roth, Tent. Fl. Germ. 3: 370. 1800. Jamesoniella fragilis Steph., Sp. Hepat. 2: 102. 1901. Lectotype (Váňa, 1975): Australia, “in alpibus australibus,” F. Müller.
Solenostoma contexta Kaal. ex Steph., Sp. Hepat. 2: 56. 1901. Lectotype (Váňa, 1975): New Zealand, North Is., Taupo, Huka Falls, 1888, Roper.
Jungermannia cambewarrana Steph., Sp. Hepat. 6: 84. 1917.
Plectocolea cambewarrana (Steph.) Herzog, Ark. Bot. 3(3): 49. 1955, nom. inval.
Type: Australia, New South Wales, Cambewarra Pass, 1903, Watts 898a.
[Fig. 151: 2, oil-bodies, p. 696]
Plants prostrate or more commonly ascending to suberect in tightly interwoven mats, resembling Solenostoma hodgsoniae but smaller, often forming tight, closely spaced rosettes, bright green to yellowish to brownish green, rarely somewhat reddish, the plants medium-sized, to 2.5 mm wide. Branching common, the plants irregularly and often repeatedly branched, the branches lateral-intercalary. Stem greenish to brownish green, the cortical cells indistinct, in a single layer of smaller cells; medullary cells lax, thin-walled. Rhizoids numerous, colorless to pale brownish, diffuse, never in bundles, arising from the ventral side of stem and from extreme bases of leaves, smooth. Leaves rather firm, vertically oriented, ± bilaterally appressed to the stem, loosely to closely imbricate, succubously oriented, the insertion variable, oblique in extreme dorsal portion, becoming subtransverse, abruptly reflexed at ventral end; leaves plane to concave, weakly asymmetric, elliptic-oval to oblate to subreniform, often broader than long, entire, 1.5–2 mm wide, 1–1.5 mm long, the apex broadly rounded or weakly emarginate; margins plane to distinctly reflexed, not undulate, the dorsal and ventral margins about equally short-decurrent. Cells thin-walled but not inflated, with small but prominent, bulging to knot-like trigones; cells of lower median sector of leaf larger, short-rectangular, (27)30–43(48) µm wide × 41–48(55) µm long, the cells in distal sector smaller, firm-walled, hexagonal, often somewhat wider than long, 28–33 µm wide and long, the marginal cells almost isodiametric, 20–27 µm in diam.; surface closely striolate-papillose (at least in median basal sector). Oil-bodies very pale grey, (2)3–6 per cell, finely granular, the spherules very slightly protruding beyond membrane, the oil-bodies elliptic to fusiform to spherical, 5.9–7.8 × 15.6–16.6 µm, some 4.9–7.8 × 11.7–13.7 µm, spherical ones 6.8 µm in diam. Underleaves absent. Asexual reproduction absent. Fungal partner absent.
Dioecious. Androecia terminal, rarely becoming intercalary, inconspicuous; bracts very little differentiated from the leaves, in 3–8 pairs, transversely inserted, widely spreading, the margins recurved, the basal portion moderately concave; antheridia 2–3 per bract, the stalk biseriate. Gynoecia terminal, typically with several lateral-intercalary innovations at some distance below the gynoecium, the subinvolucral leaves gradually larger, the bracts broadly reniform, weakly united with the base of the perianth; bracteole absent. Perianth ca. 0.5 immersed, inflated, ellipsoid, ± irregularly and sharply plicate in distal 0.3–0.5, often with short, irregular accessory ribs and scabrous near the apex, the mouth contracted to a short beak, the mouth irregularly crenulate by projecting cells; cells of beak portion short-rectangular, uniformly thick-walled, their tips irregularly projecting; cells of the perianth proper isodiametric, firm-walled, with distinct trigones.
Capsule short-ellipsoidal, the wall 2–3-stratose, 40–48 µm thick, the outer layer equaling the 2 inner layers in thickness; outer layer of cells short-rectangular, thin-walled, with short peg-like thickenings on the longitudinal walls, sporadically extending a short distance onto the outer tangential wall, the transverse walls rarely with peg-like thickenings; innermost layer of cells with longitudinal walls with thin sheet-like thickenings and ± regular, rather narrow, complete scalariform bands.
Spores yellowish brown, 16.8–19.7 µm in diam., finely papillose, the papillae distinct or forming short, irregular vermiculate ridges that do not delimit areolae. Elaters 8.6–9.1 µm wide, bispiral, the ends long-tapering and sinuous, the spirals 2.9–3.8 µm wide, not extending into the elater tips.
Distribution and Ecology : New Zealand: Stewart Island (sea level), South Island (20–310 m), North Island (95–480 m); Australia: New South Wales. In New Zealand known from Southland, Otago, Westland and Southern North Island EPs.
A species primarily of relatively low elevations in the forest zone. On stream banks it occurs over thick soil on boulders submerged to periodically inundated, and in streambeds it occurs on the tops of rocks that are for the most part above water level. Also on moist, stabilized roadside banks that are covered mostly by hepatics, mosses, often also with Blechnum and the lichen Stereocaulon. For example, at Cascade Road (just W of Jackson River, ca. 10 km SW of confluence of Jackson and Arawata rivers, Westland, 45 m) it occurred on a huge rock face of a large, vertical, bryophyte-covered roadside bank dominated by Isotachis, with Fuchsia excorticata at the base of the bank, the bank at the margin of a mature Nothofagus menziesii forest. Accompanying species on such banks are Campylopus clavatus, Chiloscyphus mittenianus, C. subporosus, Isotachis montana, Pohlia wahlenbergii and Polytrichadelphus magellanicus. The species exceptionally is alpine, occurring, for example, at the top of a rock in a rill-bed at 1360–1480 m in a mosaic of tussockland and alpine vegetation along with tarns, rills, rocky outcrops and boulderfields (Rainbow Skifield, St. Arnaud Ra., Nelson Lakes Natl. Park). Solenostoma inundatum is much more frequent at upper elevations, including the alpine zone.
Comments : Solenostoma orbiculatum resembles S. hodgsoniae in the lack of strong pigmentation, the shape and position of the leaves, and the prostrate habit and abundant rhizoids from the ventral side of the stem. Schuster (2002a) confused these species, referring to S. orbiculatum plants that are “vigorous” with “leaves to 3.0–3.6 mm × 3.3–4.1 mm” and a “capsule wall 4-layered” (key, p. 376), which match characters of S. hodgsoniae. Schuster (2002a) also illustrated these vigorous plants (figs. 353A, 354: 5–7, both as S. orbiculatum), and commented (p. 380) “this is one of the largest Solenostoma spp. known...” Solenostoma orbiculatum sensu Schuster (2002a), then, is identical to S. hodgsoniae. Solenostoma novaezelandiae R.M.Schust. may be the same as S. orbiculatum (see under “Uncertain Species”). The true S. orbiculatum is a smaller plant, with smaller cells and more uniform areolation, and the surface is decidedly striate-papillose, vs. smooth in S. hodgsoniae. It differs from S. inundatum in its prostrate habit and more obliquely inserted, dorsally assurgent leaves.
