Lepidozia digitata Herzog
Lepidozia digitata Herzog, Trans. & Proc. Roy. Soc. New Zealand 68: 45. pl. 5, m–n. 1938.
Holotype: New Zealand, near Atiamuri, Allison 72 (JE!).
[Plate 5A, B; Fig. 48; Fig. 50: 2, oil-bodies, p. 268]
Plants prostrate, the stems loosely interwoven, flexuous, with widely spreading branches, glaucous to ivory, the older shoot sectors tinged with brown, the surface dull and water-repellent; shoots small, to 0.6 cm wide, including branches. Branching exclusively of Frullania type, the branches rather short, rather distant and irregularly pinnate, the branches short and not tapering or only sporadically becoming flagelliform and microphyllous; branch half-leaf narrowly ovate, subsymmetrical, subcordate at the base, 2-lobed to ca. 0.2–0.3; first branch underleaf 2-lobed (occasionally undivided), inserted on ventral-lateral side of main shoot at branch base and obliquely to subvertically inserted. Ventral-intercalary branching not seen. Stem epidermal cells thin-walled, with a waxy coating like the cells of the leaves, the cortex in a single row of cells that are slightly smaller to or at most feebly larger than those of the medulla. Leaves with margins somewhat involute when dry, when moist plane to slightly concave, distant to contiguous, ± uniform in size, 0.35–0.55 mm wide × 0.4–0.55 mm long, spreading, nearly horizontal, the insertion broad, strongly incubous; leaves at most moderately asymmetric, (3)4-lobed to ca. 0.35 (median sinus), the distance from dorsal sinus base to insertion not much greater than that from ventral sinus to insertion, the sinuses gradually becoming deeper ventrally. Lobes subacuminate, terminating in a uniseriate row of 2–3(5) cells; cells of uniseriate row ± isodiametric or somewhat longer than wide, thin-walled, the terminal cell tapering to a rounded apex; median pair of lobes somewhat larger, 3–5(6) cells wide at base, the dorsal lobe 2–3(4) cells wide at base. Disc subsymmetric, (6)7–13(16) cells high at dorsal sinus, 6–13 cells high at ventral sinus; dorsal margin scarcely ampliate, entire or somewhat sinuate, sporadically with a 1-celled tooth, feebly cordate at the base; ventral margin entire. Cells of disc and lobes uniformly thin-walled, trigones none or minute, the median disc cells 24–35 µm wide × 29–42 µm long; median basal cells somewhat elongated but otherwise not differentiated; marginal cells of disc (especially the dorsal) often with a somewhat thickened, concave outer wall (the wall thickening somewhat crescentic and bulging into the cell lumen); surface finely granular, the cell outlines obscured by the scurfy, water-repellent coating. Oil-bodies fleeting, occupying very small portion of cell lumen, hyaline, 4–6 per disc cell, sometimes absent from most cells, finely botryoidal, rather quickly breaking up by coalescing of spherules, many oil-bodies spherical and 2.5–5 µm in diam. or ellipsoidal with acute tips and 2–2.5 × 3–6 µm, in basal cells also often absent or 1–3 per cell and larger, spherical, 4.5–5.5 µm in diam. Chloroplasts large for cell size, about the same size as oil-bodies. Underleaves inserted on 3–4 rows of stem cells, small, slightly spreading, ca. 1–1.3× stem width, ± symmetrically 3–4-fid to ca. 0.5–65 (median sinus), the sinuses broad to narrow, the lobes slender, 2–3(4) cells wide at the base and often uniseriate for most of their length, the uniseriate row of 2–3 cells and often terminating in a slime papilla; disc (1.5)2–4 cells high at median sinus, the margins plane, entire. Asexual reproduction sporadically present, via fragmenting or caducous leaf lobes, whose bases persist as truncate stubs.
Androecia and gynoecia not seen.
Distribution and Ecology : Endemic to New Zealand: South Island (480–1390 m), North Island (660–1220 m). Known from Fiordland, Otago (Rees Valley), Westland (Nelson Lakes Natl. Park), Canterbury (upper Rakaia and Waimakariri valleys), Volcanic Plateau (Mt. Ruapehu), Taranaki, Gisborne and Auckland EPs.
The few, scattered stations for the species are for the most part within Nothofagus solandri var. cliffortioides, N. fusca and N. menziesii forests ranging from 630 to 1390 m. Also known from Weinmannia racemosa – Metrosideros umbellata forest. It occurs in shaded, protected, often deep pockets (such as the hollowed recesses of tree bases), or in crevices and recesses of outcrops, or over soil of steep, mossy banks, where it may occur, for example, in a protected niche under the lip of the forest edge at the upper extremity of a stream bank (Lakehead Track, Nelson Lakes Natl. Park). Also known from below the summit of “Little Moehau” (Coromandel Forest Park, ca. 800 m) in a mosaic of Sphagnum bog and small communities of shrub-heath including Dracophyllum recurvum, Lepidothamnus laxifolius, Coprosma foetidissima, Oreobolus pectinatus, Corokia buddleoides and occasional stunted Weinmannia silvicola and Dacrydium cupressinum. At this site plants occurred very loosely creeping over soil in a shaded niche in a thicket. Also in Podocarpus nivalis – Chionochloa pallens shrubland. Accompanying species are Balantiopsis diplophylla, Bazzania nitida, Categonium nitens, Ditrichum, Leptophyllopsis laxus, Leptotheca gaudichaudii, Ptychomnion aciculare, Rhizogonium distichum and R. pennatum.
Rarely seen as an epiphyte on caudices of Dicksonia squarrosa with Hymenodon pilifer.
Comments : Lepidozia digitata is the smallest of the four New Zealand species of subg. Glaucolepidozia, with leaves at most 0.5 mm in longest dimension. Hodgson (1956) treated L. digitata as a small-leaved expression of “ L. glaucophylla ” (i.e., L. bisbifida), but it differs in being only one third the size. Lepidozia digitata is not only the smallest species of Glaucolepidozia, it has the most remote leaves (Fig. 48: 1, 8). Notable also is the apparent reproduction via fragmenting leaf lobes, whose bases persist as truncated stubs. The leaf lobes mostly end in 3 superposed cells (Fig. 48: 3, 4) but on weak phases sometimes in 4–5 cells. Stems are weaker in L. digitata than in other Glaucolepidozia species; on weak phases they may be only 6 cells high, ranging to 8–9 cells high in vigorous phases (Fig. 48: 7).
