Haplomitrium gibbsiae (Steph.) R.M.Schust.
Calobryum gibbsiae Steph., Sp. Hepat. 6: 76. 1917.
Haplomitrium gibbsiae (Steph.) R.M.Schust., J. Hattori Bot. Lab. 26: 225. 1963.
Type: New Zealand, North Is., Wairongamai Mine (“Main”), Te Aroha, 2000 ft., Nov. 1907, Gibbs 1064 – c. cal. (G!).
[Plate 1A–C; Fig. 8: 1, oil-bodies, p. 100]
Plants variable, especially in vigor, the leafy shoots isophyllous, arising from a prostrate, irregularly branched, in large part creeping or horizontal, colorless to ivory-colored rhizome that may be coralloid; rhizomatous system with numerous 1–2-celled slime papillae that produce a thick mucilaginous sheath. Leafy stems unbranched above, nearly colorless and leafless below, to 6–7.5 mm wide above (♀ plants), variable in height, to 16–25(30) mm, the shoots above the base with scattered, remote leaves that are rather abruptly larger distally. Leaves bright yellow-green, translucent to opaque, rigid and brittle, 3-ranked and subequal to equal in all ranks, the lateral weakly succubously to almost transversely inserted, variable, often strongly undulate or crispate, widely spreading, unistratose except for a 2–4-stratose basal field, suborbicular-ovate below to deltoid or rhomboidal to rhomboidal-reniform above, commonly bluntly pointed or acute at tips, widest in basal 0.25, nearly always broader than long; margins entire, or, approaching reproductive zones, occasionally with a few low, obtuse, scattered vestigial teeth or ± sinuate-lobulate, the margins with a few scattered slime papillae that are ephemeral and disappear with age. Cells in median sector variable in size from 40–50 µm wide × 45–60 µm long up to 55–65 µm wide × 65–85 µm long. Oil-bodies occupying a small portion of the cell, hyaline, ca. 15–30 to ca. 30–40 per median leaf cell, obscurely finely papillose, sporadically to commonly with a distinct depression, some broad-elliptic to more often long-fusiform to long-crescentic, the tips often becoming protracted (?early stage of breakdown), at times irregular and with 3 protracted tips and triangular in profile, 2–3.5 × 6–11.5 µm. Chloroplasts large for cell size.
Plants dioecious. ♂ Plants with antheridia in ± definite terminal receptacles (but technically axillary in the single cycle of ♂ bracts); androecial plants at times innovating freely from apex of androecium (thus with indeterminate growth), in others not or rarely so. Antheridia numerous (25–45 or more per androecium), at first ivory-white, with age cinnamon, usually with interspersed small bractlets, the stalk 4–10 tiers high. Gynoecium with ca. 20 archegonia aggregated in a terminal receptacle to 7–8 mm across, the gynoecium potentially with indeterminate growth if fertilization does not occur; if fertilization occurs, a shoot-calyptra forms. Gynoecial bracts very variable, rhombic to subrotund or irregularly rhomboid-ovate in outline, often sinuous-crispate, erect, convolute and sheathing the stem-calyptra when young, but usually becoming strongly spreading at maturity. Shoot-calyptra variable, fleshy, rigid, thick-walled, massive, green but becoming whitish green, to 8 mm high or more, the surface with polymorphous lamellae or unistratose teeth, laciniae, or ridges, the ornamentation with age may be in large part deciduous (the surface then smooth), the surface also often with sterile archegonia and slime papillae. Fungal partner a glomeromycote.
Sporophyte usually single, rarely 2 or even 3–4 shoot-calyptrae and sporophytes may form at the apex of a single gametophore. Seta to 20–25 mm long (above perigynium). Capsule ca. 0.5 × 3–4 mm.
Spores ca. 23–29 µm in diam., pale brown, covered with a limited number of compound markings that are irregular, roughened or tuberculate, obovoid to subclavate, strongly elevated, coarse, nipple- to mesa-like, distally often subtruncate and basally often somewhat constricted (best seen in spore profile); intervening spore coat smooth to locally with small finely tuberculate interstices. Spores tending to cohere in tetrads or diads until maturity, the inner faces much less strongly sculptured. Elaters 7–10 µm wide medially × 280–520 µm long, medially usually 2- sometimes 1-spiral, at times most elaters 1-spiral, the tapered and tortuous ends always 1-spiral.
Distribution and Ecology : New Zealand: Stewart Island (5–30 m), South Island (85–1400 m), North Island (300–1280 m); Australia: Tasmania (rare, cf. Engel [1982a]). Known from Rakiura (Halfmoon Bay area), Fiordland, Otago (Dunedin), Westland, Canterbury (Craigieburn Ra., Arthur’s Pass, Upper Rakaia River), Western Nelson, Southern North Island (Tararua Ra.), Volcanic Plateau and Auckland EPs.
Widely distributed in New Zealand; often rather common although rarely in any quantity. Almost always found on fresh mineral soil on soil banks created by roads, tracks, slips, or washouts, either in open sites or under forest (usually Nothofagus menziesii or N. solandri forest, but also under Agathis australis forest at Coromandel). At higher altitudes under dwarf scrub or in herbfield. For instance at Mt. Ruapehu at its North Island upper-altitude limit it was found on a stream bank of volcanic gravel and ash in low scrub of Dracophyllum recurvum, Lepidothamnus laxifolius and Gaultheria depressa var. novae-zelandiae with Triandrophyllum subtrifidum, and it occurs in high-altitude herbfields in the South Island with Celmisia angustifolia, C. petiolata, C. spectabilis, Leucogenes grandiceps and Ranunculus insignis.
In just one case recorded from a rotten log in Fiordland with the note “unusual assoc.” (CHR 135736). At low altitudes almost always accompanied by Triandrophyllum subtrifidum and Kurzia hippuroides. Other associated species are Balantiopsis diplophylla, Breutelia elongata, Campylopus clavatus, Diplophyllum domesticum, Distichophyllum pulchellum, Ditrichum difficile, D. punctulatum, Hygrolembidium acrocladum, Isotachis intortifolia, I. montana, Pallavicinia innovans, Philonotis scabrifolia, Pohlia wahlenbergii, Polytrichadelphus magellanicus, Solenostoma cryptogynum, and at higher altitudes in the South Island, Austrolophozia paradoxa, Conostomum pentastichum, Jensenia connivens and Pachyschistochila colensoana. The species appears to be a colonizer of new soil surfaces in damp places, and where such sites stabilize, it may be eventually outcompeted by taller vegetation, as indicated by its occurrence on grassy banks in Dunedin, or overtopped by dense Dendroligotrichum dendroides on a soil mound in the Craigieburn Ra. This accounts also for its sporadic occurrence and its disappearance from known localities.
Schuster (1967d, p. 45) remarked that the species is clearly “tolerant and ecologically quite unspecialized”—so long “as there is no real danger of periodic desiccation”; it occurs in a “fantastically wide diversity of habitats.” We believe, rather, that the species is quite specialized as an early colonizer except in the alpine zone where competition is much less. There is strong consistency in the accompanying species suggesting a fairly precise niche.
Comments : The species is closely allied with Haplomitrium chilensis (Schuster, 1971b, figs. 1–10), sharing with that species the rhomboidal to suborbicular leaves and the cohering spores. In H. chilensis, however, unfertilized archegonia are situated all or mostly at the base of the calyptra, which is smooth and devoid of bractlets. Spores in H. chilensis are larger (32–35 µm in diam. vs. 23–29 µm in H. gibbsiae) and bear low tubercules, under 1.5 µm high vs. 2–3 µm high in H. gibbsiae. Also, oil-bodies in H. chilensis are 20–28 per cell, ca. 4–5 × 4–6 µm vs. 32–50 or more per cell and notably smaller in H. gibbsiae. Some authors treat these species as conspecific (e.g., Hässel and Solari, 1976; Bartholomew-Began, 1991).
Bartholomew-Began (1991) placed four Indian taxa into synonymy of Haplomitrium gibbsiae; we agree with the comment in Schuster (2000a, p. 30) that “this remains to be convincingly demonstrated.”
