Macromitrium brachypodium Müll.Hal.

Thouvenot, Louis, 2019, A review of the genus Macromitrium Brid. (Orthotrichaceae, Bryophyta) in New Caledonia, Cryptogamie, Bryologie 20 (16), pp. 167-217 : 178

Macromitrium brachypodium Müll.Hal.

Botanische Zeitung (Berlin) 15: 778 (1857).

TYPE. — New Caledonia. “Île des Pins”, Cuming s.n. (lecto-, H-BR [designated by Vitt & Ramsay, 1985]; isolecto-, PC [ PC 0096548]!).

ILLUSTRATIONS AND DESCRIPTION. — Vitt & Ramsay (1985a).

DISTRIBUTION IN NEW CALEDONIA. — Macromitrium brachypodium is very rare, with only one report in South Province (type locality,Île des Pins) and one in North Province, in a very disturbed environment. Due to the scarcity of the data, its ecological range in New Caledonia remains unknown.

TOTAL RANGE. — New Caledonia and Lord Howe Island. Its occurrence in mainland Australia must be confirmed according to Vitt & Ramsay (2006).

SELECTED SPECIMEN. — New Caledonia. Province Nord, Koumac, Tiebaghi ultramafic massif, on bark in small remnant of the moist forest amongst scrubland, in the vicinity of a former mining village, 28.IX.2008, Thouvenot NC288 (PC).

DESCRIPTION

Pseudautoicous. Macromitrium brachypodium may be identified by: 1) small size of branches, less than 6 mm long, 0.8-1 mm wide; 2) branch leaves when dry erect to oblique, individually twisted, the incurved apices exposed by the margins, when wet patent to spreading, slightly sigmoid; 3) branch leaves 1.5-2.5 mm long, ligulate, obtuse to short acute, mucronate; 4) upper cells rounded, 6-8 µm, bulging, thick-walled, with c. 4 small rounded papillae; 5) basal part of leaves undifferentiated, with a few short rectangular lower cells, smooth; 6) perichaetial leaves longer than the vegetative ones, 3.5 mm long or more; 7) vaginulae naked; 8) calyptrae hairy; 9) setae very short, 1-1.5 mm long; and 10) capsules oblong, 1-1.3 mm long, smooth, rims erect, not plicate, peristomes single. It could be confused with other small species with little differentiated basal part. For differences with M. brevicaule and M. aurescens , see under the latter.

Macromitrium francii and M. pilosum have longer branches, smaller leaves with papillose basal cells, vaginulae with conspicuous long hairs and capsule mouth plicate.

In addition, Macromitrium orthostichum calyptrae have bristly hairs. See discussion in the paragraph dealing with the Francii group.