Allisoniella scottii (R.M.Schust.) R.M.Schust.
Protomarsupella scottii R.M.Schust., Rev. Bryol. Lichénol. 34: 267. 1966.
Allisoniella scottii (R.M.Schust.) R.M.Schust., Nova Hedwigia 22: 151. 1972 (1971).
Holotype: New Zealand, Stewart Is., Tin Ra., 1200 ft., Jan. 1962, Schuster 53107 (herb. Schuster).
Plants erect, carmine to blackish brown, at times appearing scorched, distinctly nitid when dry, the shoots (450)520–780 µm wide, with straight apices. Branching copious, irregular, with a system of abundant, often interwoven, creeping, microphyllous axes and erect, phototropic, leafy shoots, the erect leafy shoots toward their origin freely developing intercalary branches, microphyllous at least initially, often remaining stoloniform and either plagiotropic or geotropic, but mostly becoming erect and normal-leaved, the stolons often abundant; branches all ventral-intercalary. Stems firm, brown to deep brown, the cortex in (2)3–4 layers of thick-walled cells, the outermost layer in cross section with guttulate, elliptical lumina; medullary cells considerably larger, thin-walled. Rhizoids on leafy shoots rare or lacking. Leaves gradually larger upward, stiffly and widely spreading, pectinately distichous, never dorsally assurgent, contiguous, somewhat adaxially concave, but not canaliculate or folded, transversely oriented and inserted, not reflexed on sterile shoots, short-oblong to oblong-subquadrate to oblong-ovate, longer than wide, 375–400 × 310–340 µm to 470–510 × 340–400 µm, bifid to 0.4–0.5; lobes curved toward shoot apex or incurved, on flattened leaves only weakly divergent so that leaves are parallel-sided for most of their length, the lobes typically plane or slightly adaxially concave (rather than abaxially sulcate) but sporadically feebly and imperceptibly abaxially sulcate, acute, 14 or more cells wide at base, the tips plane or incurved, acute to blunt; sinus acute. Cells in vertical columns, thick-walled, the middle lamella at times darker, the cells very small, median lamina cells 8–12 µm wide × 12–16 µm long; marginal cells of lobes 8–11 µm wide; basal cells not distinctly elongated, 11–13 µm wide × (13)15–22 µm long; surface coarsely papillose with close to contiguous papillae or finely and inconspicuously papillose. Oil-bodies (Schuster, 1966a) (1)2–3(4) per cell, rather large, faintly granular, almost smooth, ellipsoidal or oblong-ellipsoidal to subspherical, (2.6)3–3.5 µm to 2.8–3.2(4) × 4.5–6(7) µm; marginal cells with smaller oil-bodies. Gemmae unknown.
Autoecious. Androecial branches often arising from the ♀ ones, or sometimes vice versa, the androecia eventually becoming intercalary, compactly spicate; bracts in 4–5(6) pairs, closely imbricate, the larger bracts ventricose at the base, with lobes often lower and blunter than on leaves; antheridia 1–2 per bract, the stalk uniseriate. Gynoecia terminal on long leafy axes, the bracts typically smaller than uppermost leaves, closely sheathing basal sector of perianth, ovate-quadrate, asymmetrically bilobed to 0.35, the dorsal lobe narrower and shorter, the lobe margins entire; bracteole large, connate for ca. 0.5 with bract on one side, but free or short-connate on the other side, oblong-ovate, bilobed to 0.35. Perianth long-emergent, without subtending perigynium, the mouth decolorate with age, oblong-ovoid or narrowly ovoid, deeply 4–5-plicate for 0.75 its length (and cruciate in cross section), rarely with lower accessory plicae distally, the perianth somewhat narrowed toward the mouth; mouth truncate, sinuous or entire to remotely crenulate with weakly projecting cells, the cells at mouth guttulate, with rounded lumina, similar to cells below them.
Seta with 8 rows of outer cells and (3)4 rows of internal cells. Mature capsules observed.
Distribution and Ecology : Endemic to New Zealand: Stewart Island (360 m), South Island (1160–1310 m).
Allisoniella scottii forms fuscous to blackish patches over rocks or stones, at the edges of insolated shallow streams (Stewart Island) or with Herzogobryum atrocapillum and Isophyllaria attenuata on the edge of a small alpine tarn at 1160–1310 m in the Paparoa Ra. (NE of Mt. Euclid, headwaters of Awakiri River, South Island, leg. Schuster). Schuster (1996a, p. 13) remarked that the Paparoa Ra. plants “occurred in full sun, forming scorched patches, at the edge of a small alpine tarn, at the edge of the water line, forming a black crust—under conditions where submersion and desiccation regularly succeed each other.” A specimen from the same locality (Glenny 8117) was found in a cushion bog on thin soil over stones, among Oreobolus pectinatus – Donatia novae-zelandiae cushionfield, with Isophyllaria attenuata and Cephalomitrion aterrimum.
Comments : This species has, when sterile, “an unmistakeable similarity to the scorched-appearing Marsupellae, such as M. sparsifolia ” (Schuster, 1966a, p. 267), and, calling attention to this character, the species was initially placed in a genus Protomarsupella (Schuster, 1966a). Characters that suggest Marsupella are the geotropic, stoloniform axes issuing from the lower ends of leafy erect shoots; the stiffly spreading, deeply bifid leaves; the very narrow ventral merophytes, without a trace of underleaves; and the relatively large oil-bodies (for the cell size), mostly 2 or 3 per cell. However, the long, markedly emergent perianths and lack of a perigynium preclude any closer affinity to Marsupella. If only sterile plants are present, then branch type should be checked: branches are ventral-intercalary in Allisoniella scottii rather than lateral-intercalary in Marsupella.
Plants occur in small, pure mats, with a characteristic growth pattern: a dense mass of extensive plagiotropic and geotropic, leafless, interwoven axes gives rise to numerous erect leafy stems of limited height. The erect leafy shoots are of similar height. This is due to androecial shoots being determinate after forming at most 3 androecia, and gynoecia failing to innovate (see Schuster, 1996a for comments and also for remarks on sexuality).
Schuster (1996a, p. 10) remarked “erect leafy shoots that fail to produce gametangia are rare; indeed, shoots that remain sterile indefinitely probably do not exist.” We have observed populations with many sterile shoots, with only a few perianths and androecia. As with some other Cephaloziellaceae, perianths mature even if fertilization fails to take place.
