Paracromastigum drucei (R.M.Schust.) R.M.Schust.
Pseudocephalozia drucei R.M.Schust., Nova Hedwigia 10: 22. 1965.
Holotype: New Zealand, North Is., Mt. Egmont, Schuster 48979.
Plants whitish green, becoming tinged with brownish to reddish brown to reddish (at least in exposed sun forms), the shoots minute. Branching copious and irregular, the branches of lateral- and ventral-intercalary types; Acromastigum - and Frullania -type branches very rarely present; stoloniform axes common. Stems with cortical cells large and thin-walled, in 12 or fewer rows, moderately to distinctly larger than medullary cells, in surface view subquadrate to short-oblong, under 2× as long as wide usually; medullary cells thin-walled. Main shoots with 5–8 cortical cells intervening between successive leaves on either side. Leaves small, very remote, suberect to erect, concave, the concavity turned toward the stem, the insertion transverse to feebly incubous, extending to stem midline dorsally; leaves formed from relatively few cells, 6–8 to 11–12 cells wide in median sector, 6–8 cells wide at the base, 2–3(4)-lobed, the lobes triangular to somewhat attenuate, usually comprised of a few, usually 3–6, large cells, the cells larger than those of the disc, the dorsal lobes 3–4 cells broad at base, the leaves often asymmetrically lobed, the two ventral lobes reduced and only 1–2-celled, each terminating in a slime papilla, or the lobe reduced to a slime papilla; disc 2–4 cells high. Cells of leaves little or scarcely elongated, thin-walled, devoid of trigones; surface of lobes and disc papillose, the disc at times obscurely so. Oil-bodies (fide Schuster, 2000a) present at least in isolated cells, 1 or 2 per cell, colorless, botryoidal. Underleaves ca. 0.5 (rarely more than half) the leaves in size, few-celled, usually asymmetric and with one well-developed lobe formed from 5–6 cells and 2–3 reduced lobes each formed of 1–2 cells, the terminal cells typically reduced to a slime papilla, the half or more of the underleaf that forms reduced lobes distally often develops 2–3 rhizoids from a few small basal cells.
Androecia and gynoecia not seen.
Distribution and Ecology : Endemic to New Zealand: North Island (1200–1630 m). Known only from the volcanic region of the North Island (Volcanic Plateau and Taranaki EPs), where it occurs as a pioneer on fine-grained, exposed volcanic soils in alpine and penalpine regions.
At the headwaters of Mangawhero River (Tongariro Natl. Park, 1630 m) plants occurred over soil deep in rock crevices in an alpine fellfield. Also at Mangatepopo Stream below Soda Springs (Tongariro Natl. Park, ca. 1200 m) over soil in an area of alpine vegetation with scattered frequent rocky outcrops.
Comments : Paracromastigum drucei differs from P. fiordlandiae in 1) leaves formed from relatively few cells, 6–8 cells broad at the base and 7–8(12) cells wide in median sector, with lobes of few, usually 3–6, large cells; and 2) underleaves few-celled, typically with one well-developed lobe formed from 5–6 cells and 2–3 reduced lobes each formed of 1–2 cells, the terminal cells typically reduced to a slime papilla. The half or more of the underleaf that forms reduced lobes distally often develops 2–3 rhizoids from a few small basal cells, while the half of the underleaf with the well-developed lobe lacks them. The asymmetry seen in the underleaves at times also occurs in the lateral leaves, with the two ventral lobes reduced and each terminating in a slime papilla. Also, oil-bodies are present, though in isolated cells, vs. completely lacking in P. fiordlandiae. Moreover, the ecology of these species is entirely different: P. drucei is a pioneer on fine-grained, exposed volcanic soils in alpine and penalpine regions in the volcanic region of the North Island whereas P. fiordlandiae is found on peaty ground in the snow tussock (Chionochloa) zone of the South Island.
