Lepidozia serrulata J.J.Engel
Lepidozia serrulata J.J.Engel, J. Hattori Bot. Lab. 96: 273. f. 1. 2004.
Holotype: New Zealand, Stewart Is., Rakiura Natl. Park, Mt. Rocky summit area, 530 m, Engel, von Konrat & Braggins 24293 (F); isotype: (AK).
Plants loosely prostrate, rather rigid, the hair-like leaf tips lending dried plants a subhoary aspect, pale yellow-green, the shoots medium-sized, to 1.7 cm wide, including branches. Branching nearly exclusively of Frullania type, regularly and rather densely 2-pinnate, the branches, particularly the secondary ones, ventrally secund, both at times abruptly becoming flagelliform and whip-like; branch half-leaf subsymmetric (the dorsal margin a little dilated), ovate, 2-lobed, the dorsal margin sparingly and irregularly denticulate-dentate, at times with a few spinose teeth, the ventral margin with a few, stronger, spinose teeth; first branch underleaf 3–4-lobed, inserted on juncture of branch base and main shoot and aligned with underleaves of branch, asymmetric, the sinuses of unequal depth. Ventral-intercalary branching occasional, short, leafy or flagelliform. Stems rather soft and flexuous, the cortical cells in 1 layer of thick-walled cells that are slightly larger than medullary cells; medullary cells distinctly firm-walled. Leaves rigid, fragile, strongly concave, imbricate and nearly or completely hiding stem in dorsal view, 0.9–1.1 mm long at longest point, 0.8–1.1 mm wide at widest point, obliquely spreading, the insertion distinctly incubous, not or slightly recurved at dorsal end; leaves distinctly asymmetric, unequally 4-lobed, the leaves divided to ca. 0.5–0.55(0.7) (median sinus), the dorsal lobes subparallel, the 2(3) ventral lobes moderately divergent, the distance from dorsal sinus base to insertion much greater than that from ventral sinus to insertion, the dorsal lobes perceptibly to distinctly paired, the dorsal-most sinus often notably shallower, the remaining sinuses then becoming gradually deeper ventrally. Lobes of differing shape, the dorsal pair of lobes caudate, the third lobe subcaudate to sublinear, the ventral-most lobe linear to attenuate, the lobes typically entire, occasionally with 1 small tooth or spine, the dorsal lobes 9–13 cells wide at base, the ventral lobe 6–13 cells wide at base, the lobes terminating in a uniseriate row of (3)4–7(8) cells; cells of uniseriate row moderately elongated (2.3–4.3[5.3]:1), thick-walled and with the septa thickened and swollen, the tip cell thickened at the summit. Disc distinctly asymmetric primarily due to strong dilation of dorsal sector, the disc 19–25 cells high at dorsal sinus, 7–12 cells high at ventral sinus; dorsal margin sparingly and irregularly denticulate-dentate, at times with a few small spinose teeth, the teeth often composed of only 1–2 cells; ventral margin much shorter than the dorsal, entire or occasionally with a lacinia, which if especially well developed makes the leaves appear 5-lobed. Cells of disc-middle evenly thick-walled, slightly to moderately elongated, 14–24 µm wide × 28–34 µm long, tending to occur in ± regular longitudinal files; cells in the ampliate sector ± isodiametric, 16–22 µm wide and long; median basal cells enlarged and forming an ill-defined field; surface finely striate-papillose. Underleaves 1.5–2× stem width, spreading, symmetrically basically 4-fid to 0.5 (median sinus), the lobe base tapering distally or ± parallel-sided, 11–15 cells wide at extreme base, the distal portion acuminate-subcaudate, the lobes with 1–2 accessory, at times opposed, teeth or cilia that are always smaller than the lobe, the distal sector terminating in a single cell or a uniseriate row of 2–6 cells; disc 11–15 cells high at median sinus, the disc margins on each side with 1–2 cilia.
Androecia and gynoecia not seen.
Distribution and Ecology : Endemic to New Zealand: Stewart Island (5–530 m).
Plants occur in protected, non-exposed sites, such as under cover of Leptospermum scoparium in mosaic communities of dense heath-forming shrubs to 3 m tall, penalpine herbs, and dwarf heaths to 0.5 m tall, with vegetation dominated by stunted L. scoparium and Dracophyllum and a ground tier including Empodisma minus (at type locality). Also under an open canopy of stunted Dacrydium cupressinum and dense Dracophyllum understory (ca. 2–3 m above river behind Belltopper Falls). The species also occurs in mosaic communities of stagnant ponds, Sphagnum bog, open L. scoparium – Dracophyllum heath to 1–2 m tall, and dense communities of Gleichenia dicarpa and E. minus (Freshwater Landing). At Pryse Peak Lepidozia serrulata occurs in open forest, including stunted Dacrydium cupressinum, Podocarpus hallii, Olearia colensoi, Gahnia, Blechnum and bryophyte cushions on the forest floor. The species is a ground-dweller, occurring on the floor, either over soil or over a layer of thick humus, and at times may form soft cushions.
Comments : Lepidozia serrulata is one of only four New Zealand members of the genus with regularly and consistently bipinnate branching (Fig. 45: 1), the others being L. spinosissima, L. microphylla and L. pendulina. The last three species are all erect plants with rigid, woody stems with slender and drooping branches and have leaves that are transversely inserted, typically distant and vertically oriented. Lepidozia spinosissima, L. microphylla and L. pendulina are segregated into three different subgenera in Schuster (2000a) and Engel and Schuster (2001), i.e., Dendrolepidozia, Mastigolepidozia and Notholepidozia respectively. Lepidozia serrulata belongs to subgenus Notholepidozia and is related to the more specialized taxa in the subgenus, i.e., with L. kirkii and L. hirta of the same section, sect. Kirkii. It differs from L. kirkii and L. hirta in having the dorsal pair of lobes terminating in a uniseriate row of 4–7 cells, the cells at least at times moderately elongated (2.3–4.3[5.3]:1) (Fig. 45: 12, 13).
