Acromastigum mooreanum (Steph.) E.A.Hodgs.
Bazzania mooreana Steph., Hedwigia 33: 1. 1894.
Mastigobryum mooreanum (Steph.) Steph., Sp. Hepat. 3: 539. 1909.
Acromastigum mooreanum (Steph.) E.A.Hodgs., Trans. Roy. Soc. New Zealand 82: 19. 1954.
Type: Tasmania, Jones Walk, Spreut (= Sprent) River, 600 ft., Moore 65, com. Ferd. v. Mueller (!).
[Fig. 90: 3, 4, oil-bodies, p. 410; Fig. 91]
Plants stiff and wire-like, suberect to erect, yellowish to reddish brown (the stem often becoming blackish); plants when dry distinctly nitid and with leaves strongly ventrally deflexed; shoots small, to 1.2 mm wide, subcircinate at the tip. Branching repeatedly pseudo-dichotomously furcate, the branches of Frullania type, widely spreading; branch half-leaf ± symmetric, ovate, undivided, nonvittate, tapering to a sharp apex; first branch underleaf 2–3-lobed, inserted on ventral-lateral side of branch at juncture of main axis and branch. Acromastigum -type branches common, stoloniform. Ventral-intercalary branches occasional, leafy. Stem stiff and brittle, the cortical cells strongly differentiated, much larger than the medullary cells (ca. 2.5:1), in 7 rows, the radial walls thick, the outer tangential walls strongly thickened; medullary cells thin-walled. Leaves stiff and brittle, imbricate, allowing little of stem exposed in dorsal aspect, widely spreading, strongly deflexed, the ventral lobes of opposing leaves often approximate in ventral aspect, the leaves moderately convex; leaves vittate, 260–305 µm wide × 600–720 µm long, strongly incubous, subfalcate, asymmetrically narrowly ovate; apex unequally bilobed to ca. 0.5, the ventral lobe 2–4× longer than the dorsal, the lobes entire; dorsal lobe acute, the cells often with trigones smaller than those of ventral lobe, the cells at times evenly thick-walled, the lobe 4–5 cells wide at base, terminating in a single cell or a uniseriate row of 2 cells; ventral lobe subulate, 3–4 cells wide at the base and biseriate for much of its length, terminating in a single cell or more commonly a uniseriate row of 2–3 cells, the terminal cell somewhat elongated, tapering to a point; dorsal margin somewhat ampliate, extending to middle of stem or somewhat beyond, cordate to auriculate, at times with a lobuliform auricle near insertion, the basal sector often also with 1–2 slime papillae, the margin entire or somewhat sinuate at the base; ventral margin nearly straight or somewhat incurved, with a slight basal dilation, entire. Cells of leaf with a strong vitta of distinctly larger, rectangular cells occupying the ventral half of leaf (and continuing into the ventral lobe) but without a distinct marginal row or rows of smaller, isodiametric cells, the vitta 4–5 cells wide in basal half of leaf; cells of vitta with knot-like trigones, 26–37 µm wide × 29–39(42) µm long; cells in dorsal sector of leaf becoming much smaller, isodiametric, 11–22 µm wide and long, uniformly thick-walled, without trigones; free walls of marginal cells of ventral lobe and ventral margin of disc strongly thickened; surface smooth. Oil-bodies pale smokey grey, 2–7(8) per vitta cell (6–12 per vitta cell fide Schuster, 2000a, fig. 111), 2–3 per non-vitta cell, broadly elliptic, coarsely and irregularly botryoidal, with age the spherules coalesce and the segments become fewer and the oil-body shape becomes subglobose. Underleaves rigid, small and inconspicuous, very firmly attached at a thick base, distant, ± squarrose at base and becoming erect, convex, broadly elliptic to subrectangular, much broader than long, deeply and ± equally 3-lobed to ca. 0.5; lobes 4–6 cells wide at base, the apex broadly rounded, entire, terminating in 2–4 laterally juxtaposed cells; disc margins cordate to subauriculate, narrowing abruptly to a narrow insertion; disc margins entire; cells of disc and lobes strongly thick-walled; surface smooth.
Androecia and gynoecia not seen.
Distribution and Ecology : New Zealand: Auckland Islands (15–55 m), Stewart Island (5–530 m), South Island (200–1050 m); Australia: Tasmania. In New Zealand known from Fiordland (Secretary Island) and North Westland (Paparoa Ra.) EPs.
In New Zealand known from several stations on Stewart Island and South Island. On Stewart Island it occurs in small bryophyte mounds deep in thickets within mosaic communities of dense heath-forming shrubs to 3 m tall, penalpine herbs and dwarf heaths to 0.5 m tall; dominated by stunted Leptospermum scoparium and Dracophyllum and a ground tier including Empodisma minus (Mt. Rocky summit area, 530 m). Also on ground under Leptospermum in mosaic communities of stagnant ponds, Sphagnum bog, open Leptospermum scoparium – Dracophyllum heath to 1–2 m tall and dense communities of Gleichenia dicarpa and Empodisma minus (Freshwater Landing, 5 m). Also on the sides of small cushions in open shrubland consisting of Leptospermum scoparium, Olearia colensoi, Gahnia and emergent Podocarpus hallii (Pryse Peak, 350–355 m). In the South Island occurring in Fiordland (Facile Harbor, Allan [MPN!] and Secretary Island) and in the Paparoa Mtns. (N flank of Mt. Euclid and ca. 0.5 km SE of Morgan Tarn, both at 1050 m) where it occurred with Dicranoloma on a granite ledge in a moist Nothofagus menziesii – Dracophyllum traversii forest. It is found with Bazzania adnexa, B. involuta, Clandarium xiphophyllum, Heteroscyphus decipiens, Lepidozia ulothrix, Schistochila chlorophylla and Wijkia extenuata.
Comments : Acromastigum mooreanum is apparently rather rare in New Zealand in comparison to the closely related A. anisostomum. The “crossed swords” formed by the greatly elongated, strongly ventrally deflexed and approximate ventral leaf lobes (seen in ventral aspect) will readily distinguish this species. A suite of features involving the vitta, the size and shape of the ventral lobe, and the leaf areolation also differentiate this species from A. anisostomum.
