Lepidozia acantha J.J.Engel
Lepidozia acantha J.J.Engel in J.J.Engel & R.M.Schust., Fieldiana, Bot. N.S. 42: 71. f. 27. 2001.
Holotype: New Zealand, North Is., Whakarewarewa Thermal Reserve, Sept. 1939, Hodgson s.n. (F); isotype: (CHR).
Plants procumbent, in thin mats, slender, flexuous, with spreading branches, pale green, nitid, delicately spinescent when dry, the shoots small to medium, to 1 cm wide (stem to branch extremities). Branching nearly exclusively of Frullania type, somewhat irregularly and loosely pinnate, the branches slender, short to elongated and distinctly whip-like, long-flagelliform and microphyllous; secondary branches not seen; branch half-leaf symmetric, linear, bilobed to 0.5; first branch underleaf undivided and subulate, rarely bilobed, inserted on ventral or ventral-lateral face of main axis and aligned with branch underleaves. Ventral-intercalary branches sporadic, leafy. Leaves when dry strongly ventrally secund, with the lobes straight to slightly incurved; leaves when moist strongly spreading, plane or (when lobes slightly incurved) slightly concave, contiguous to distant, with much of stem exposed in dorsal aspect, 0.45–0.65 mm long at longest point × 0.5–0.65 mm wide at widest point, the insertion distinctly incubous; leaves ± symmetric, deeply and subequally 4-lobed, divided to ca. 0.5–0.6 (median sinus), the distance from dorsal sinus base to insertion slightly greater than that from ventral sinus to insertion. Lobes long and narrowly attenuate, subequally divergent, the dorsal lobe 5–7 cells wide at the base, the ventral lobes similar to the dorsal in size, the lobes terminating in a single cell or more commonly in a uniseriate row of 2–4 cells; cells of uniseriate row somewhat elongated (up to 2.5:1), evenly thick-walled; surface of lobes closely and distinctly short striate-papillose. Disc subsymmetric, subdeltoid, 8–10 cells high at dorsal sinus, 5–8 cells high at ventral sinus, the margins entire, the dorsal margin straight (at most feebly ampliate), the ventral straight. Cells of disc-middle moderately and evenly thick-walled, subquadrate to somewhat longitudinally elongated (particularly those aligned with second lobe), 18–23 µm wide × 27–41 µm long; median basal cells larger, in one to several rows; surface of disc closely striate-papillose, becoming long-striate at disc base. Underleaves inserted on 5–7 rows of stem cells, rather large for plant size, ca. 1–1.5× stem width, plane, spreading, symmetrically quadrifid to ca. 0.5–0.6, the lobes long and slenderly attenuate, ending in a single cell or more often a uniseriate row of 2–3 cells, the cells of uniseriate row quadrate to elongated; disc 4–6 cells high at median sinus; disc margins entire.
Androecia and gynoecia unknown.
Distribution and Ecology : Endemic to New Zealand and known from a limited number of collections. Found at a single South Island station at Camp Creek (Westland, 900 m). North Island populations are from the Rotorua area, at 185 m under Leptospermum scoparium and from edges of shaded paths in thermal spring areas, and on a very rotted, decorticated, bryophyte-covered log in a mixed broadleaf–podocarp lowland forest (Pakiri Scenic Reserve, SSE of Mangawhai Heads, Northland, ca. 30 m).
Comments : Resembling Lepidozia bidens in the narrowly attenuate lobes, the elongation of uniseriate row cells, and the feebly ampliate dorsal margin. It differs in the distinctly incubous leaf insertion (Fig. 41: 1), the deeply and subequally lobed leaves (Fig. 41: 6), the closely papillose leaf surface (Fig. 41: 7, 8), the larger underleaves with slenderly attenuate lobes, and the smaller size.
The disc surface is closely striate-papillose (Fig. 41: 8), as in Lepidozia laevifolia and its var. acutiloba. Lepidozia acantha differs from the latter in the narrowly attenuate leaf lobes, and from the former in the ± symmetrical leaves, the lobes subequally spreading, the ventral lobes not widely divergent from the paired dorsal lobes.
The species differs from all other New Zealand members of Lepidozia except L. elobata by the consistently undivided first branch underleaves (Fig. 41: 3, 5). The first branch underleaf is subulate in L. acantha vs. rather broad-based and strongly tapered in L. elobata. Also, in L. elobata the half-leaf is only 0.2–0.25 bifid vs. 0.4–0.45 in L. acantha; leaf lobes are much less tapered and their end cells are scarcely elongated. It is notable that undivided first branch underleaves are also found in many Telaranea species, as is the presence of 3-lobed branch leaves (Fig. 41: 5); L. acantha can be distinguished from superficially similar diminutive Telaranea species by the absence of a hyaloderm (Fig. 41: 2), and the papillose surface of the leaves.
