Macromitrium panduraefolium Thouvenot

Thouvenot, Louis, 2019, A review of the genus Macromitrium Brid. (Orthotrichaceae, Bryophyta) in New Caledonia, Cryptogamie, Bryologie 20 (16), pp. 167-217 : 197

Macromitrium panduraefolium Thouvenot

( Fig. 15 )

Cryptogamie, Bryologie 39: 444-448, figs 1-24 (2018).

TYPE. — New Caledonia. South Province, Dumbéa, Montagne des Sources Nature Reserve, Neocallitropsis plateau, 745 m, 21.IX.2016, Thouvenot NC2329 (holo-, PC [ PC 0786119]!; iso-, author’s private herbarium).

ILLUSTRATIONS AND DESCRIPTION. — Thouvenot (2018).

DISTRIBUTION IN NEW CALEDONIA. — M. panduraefolium was collected in two remote massifs, separated each other by 75 km and from Mt Humboldt, the locality of the nearest other aristate Macromitrium , by respectively 47 and 33 km. Therefore, this species is also candidate to micro-endemic status.

TOTAL RANGE. — Endemic to New Caledonia, only known from two localities in South Province.

SELECTED SPECIMENS (PARATYPES). — New Caledonia. Province Sud, Boulouparis, Mt Do, corticolous, on the bark at the basis of a dead Araucaria sp. ; wet forest in an ultramafic massif; altitude 990 m; coordinates 21°45’S, 165°59’E; 15.IX.2016, L. Thouvenot NC2306; Dumbéa, Montagne des Sources Nature Reserve, Neocallitropsis plateau, on the bark of Dacrydium araucarioides in mountain scrubland in an ultramafic massif; 22°08’S, 166°35’E; altitude 745 m; 21.IX.2016, L. Thouvenot NC2334, NC2386 (PC0786118!).

DESCRIPTION

Macromitrium panduraefolium is characterized by: 1) small branches fusiform, with leaves spirally appressed in dry condition, erect when moist; 2) costae of the vegetative and perichaetial leaves excurrent in conspicuous hyaline aristae; 3) branch leaves oblong-ligulate constricted at middle, rounded to obtuse or truncate at apex; 4) upper cells relatively large with thick bulging external walls and small acute papillae; 5) basal cells linear, all or most smooth, with straight lumina; and 6) exserted capsules with medium sized setae.

It may be separated from Macromitrium rufipilum by its smaller size in all features, branch habit in dry condition and original branch leaf outline.

Macromitrium panduraefolium is corticolous, the specimens were collected on the bark of endemic gymnosperms of the genera Dacrydium and Araucaria in mountain scrublands and wet forests on medium elevation ridges, 745-990 m a.s.l., in ultramafic massifs.

Figures

FIG. 15. — Macromitrium panduraefolium Thouvenot: A-F, branch leaves; G, H, branch leaf apices; I, transverse section in top quarter of branch leaf; J, capsule; K, M, perichaetial leaves;L, upper part of dry branch with sporophyte.All drawn from the holotype.Scale bars:A-F,J, K, M, 500 µm;G,H,100 µm;I, 20 µm;L, 1 mm.