Haplomitrium ovalifolium R.M.Schust.
Haplomitrium ovalifolium R.M.Schust., Bryologist 74: 136. f. 11–29. 1971.
Holotype: Campbell Is., sea cliffs of Mt. Yves Villarceau, ca. 200–275 ft., at Penguin Bay, Schuster 70-3248 (F!).
Plants isolated to loosely gregarious in growth, slender, clear green, small, the shoots occasionally to 1.5–2.2 mm wide (including the leaves), to 8–16 mm tall. Branching irregular, rather copious; leafy erect axes often with supra-axillary long axes, initially leafless and horizontal, soon erect and leafy (thus 2–3 or more leafy axes clustered together, united by leafless stoloniform sectors); older shoot sectors producing free, often highly elongated, leafless, stoloniform, creeping to geotropic axes. Shoots typically leafy throughout, with lower leaves soon attaining a mature size and form, the leafy shoot thus subequally leafy throughout, except that at and near gynoecia the leaves become moderately larger. Leaves rather rigid, transverse, often obliquely to widely spreading, unistratose except at extreme base, nearly flat, relatively uniform, typically ovate to ovate-lanceolate, the length always clearly greater than width (mostly 1.2–1.5× longer than wide), occasionally bifid nearly to base; apices narrowly rounded to blunt, to bluntly pointed; leaf base only moderately narrowed; margins entire or obscurely repand to repand-dentate with blunt angulations. Cells opaque, chlorophyllose, thin-walled, the cells in leaf middle from 24–32 × 25–38 µm to (20)25–32(36) × 36–55(60) µm. Oil-bodies (Schuster, 1971b) ca. 25–35 per cell, variable, ± clearly botryoidal, small, from few-segmented to coarsely botryoidal, subspherical and 2.5–2.8(3.5) µm in diam. to ovoid and 2.2 × 3.5 µm to 3–3.2 × 4–5(6.5) µm; chloroplasts averaging subequal to or smaller than oil-bodies in size, ca. 2.5–3.5 × 5–6 µm. Fungal partner a glomeromycote.
Plants dioecious. ♂ Bracts and subfloral leaves often closely juxtaposed lending the ♂ shoots a capitate appearance, a triquetrous arrangement of leaves (and bracts) in androecial region lacking—the arrangement at least imperfectly spiral; the bracts highly variable, but always lingulate to ovate, always narrow, always at least 1.2–1.5× longer than wide, often much longer. Antheridia never in a terminal disc, axillary in bracts, orange-yellow. Gynoecial bracts leaf-like, retaining the narrow form of leaves but slightly larger than leaves, ovate to elliptical to, occasionally, obovate, always clearly longer than wide. Archegonia rather few, typically on the apex of a ± conoidally convex shoot apex subtended by 3 bracts, isolated archegonia occasionally present in the axils of subfloral bracts. Shoot-calyptra cylindrical, small, yellowish green (postmature), seemingly smooth (a single, old shoot-calyptra seen). Otherwise unknown.
Distribution and Ecology : Endemic to New Zealand: Campbell Island, South Island (920–1650 m), North Island (1280 m). Known from Otago (Old Man Ra.), Westland (Mt. Brown, McCullough Pass), Canterbury (The Spike) and Western Nelson (Marino Mtns.).
In the South Island known only from the alpine zone. Unlike Haplomitrium gibbsiae, apparently confined to areas that have undergone no human disturbance and, apparently, lacking from forested regions. Found in Nelson on sinkhole walls with Chionochloa pallens, C. australis and Marsippospermum gracile; elsewhere in the South Island under pallens and C. flavescens tussocks on damp, south-facing aspects. It shares with H. gibbsiae a preference for mineral soil rather than humus. It has been found associated with Brachythecium paradoxum, Chiloscyphus subporosus, Diplophyllum dioicum, Gackstroemia alpina, Isotachis intortifolia, Marchantia foliacea, Megaceros leptohymenius, Notoligotrichum australe, Pachyschistochila succulenta, Riccardia aequitexta, Solenostoma totipapillosum, Telaranea lindenbergii, T. tetrapila and Verdoornia succulenta.
Comments : Haplomitrium ovalifolium is a much smaller plant than H. gibbsiae, with leaves much longer than wide, basically elliptical in form and widest medially vs. nearly always broader than long and widest in basal 0.25 in H. gibbsiae. The leaf form (of regions and/or plants lacking bifid leaves) is much as in H. minutum. Haplomitrium ovalifolium is unique in the genus in its highly variable form and orientation of the leaves: Androecial shoots show sporadic to frequent leaves that are divided to the base, so that the leaf consists of two autonomous, lingulate segments.
Gametangial position is noteworthy. Antheridia are axillary in leaves and/or bracts when not scattered and are never in terminal groups. Gynoecial shoots have only 6–8 archegonia at the apex of a convex, conoidal shoot tip, but isolated archegonia sporadically are present axillary in subfloral leaves.
