Macromitrium leratii Broth. & Paris

Thouvenot, Louis, 2019, A review of the genus Macromitrium Brid. (Orthotrichaceae, Bryophyta) in New Caledonia, Cryptogamie, Bryologie 20 (16), pp. 167-217 : 191-194

Macromitrium leratii Broth. & Paris

( Figs 1E , 13 )

Öfversigt af Finska vetenskaps-societetens förhandlingar 48 (15):

12 (1906).

Macromitrium salakanum var. majus Besch., Annales des Sciences naturelles, Botanique sér. 5, 18: 210 (1873). — Type: New Caledonia, “Ad arborum truncos montis Mou, 1200 m ”, Balansa 2978, 2981; “in monte Mi”, Balansa 916 (lecto-, designated here: Balansa 2978 PC[PC0138026]!; syn-, PC[PC0138024, PC0138025, PC0138027, PC0138028]!).

Macromitrium leratii var. erectifolium Thér. Rev. Bryol. 48: 16 (1921). — Type: New Caledonia, Île des Pins, 1874-76 (lecto-, designated here fide Guo in Sched. [2007]: PC0083688!) syn. nov.

TYPE. — New Caledonia. “in silvaticis montis Dzumac, alt. 1100 m. et in monte Ouin, ad arbores, alt. 1000 m ”, Le Rat s.n.; Prony, Etesse s.n. (lecto-, “In silvaticis montis Dzumac, alt. 1100 m, VII.1904 ”, Le Rat s.n., “marked as a probable isotype in H-BR by D. H. Vitt in 1983” ( H) [ Vitt et al. 1995]; syn-, H; isosyn-, Mt Ouin, VII.1905, Le Rat s.n., PC [ PC 0096510, PC 013779]!).

DISTRIBUTION IN NEW CALEDONIA. — Present in North and South Province.

TOTAL RANGE. — East Australia, Lord Howe Island, New Caledonia.

SELECTED SPECIMENS. — New Caledonia, Province Nord, Ponérihouen, Mt Aoupinié, 950 m, 2.X.2012, Larraín 35612; Hienghène,

trail to La Guen, 10.X.2012, Thouvenot NC1025; Touho, Pombeï, 415 m, 12.X.2016, Thouvenot2287; Province Sud, Yaté, base of Pic du Grand Kaori, 250 m, 22.X.2012, Thouvenot NC734; Rivière Bleue Nature Parc, La Tranchée, 220 m, 19.X.2016, Thouvenot NC2379 (PC); Pont Germain, 170 m, 5.X.2016, Thouvenot NC2390; Mont-Dore, Demazures forest, 360 m, 28.IX.2016, Thouvenot NC2362

(PC); Païta, Mt Dzumac, 920 m, 19.IX.2016, Thouvenot NC2237 (PC); Mt Mou, 1110 m, 17.IX.2016, Thouvenot NC2231; Dumbéa, Mt Bouo, 930 m, on rocks, 16.IX.2016, Thouvenot NC2301 (PC); Thio, Mt Ningua, 1120 m, 29.IX.2012, Thouvenot NC869; Dumbéa, Montagne des Sources Nature Reserve, 28.IX. 2012, 550 m, Larraín 35473; Boulouparis, Mt Do, 1000 m, 27.IX.2012, Larraín 35412.

DESCRIPTION

Pseudautoicous

Dwarf male plants on leaf axis of female branches.

Plant

Large to medium, young upper parts green, main parts usually red brown to dark brown, rarely olive green, creeping stems densely branched.

Branches

Thick and long, (4-)10-25(-40) mm long, 1.5-2 mm wide, straight to slightly curved, simple or furcate, when dry curly, with leaves erect to patent, individually twisted, carinate, the apices circinate to coiled, exposed by the margins, when moist spreading and sinuous with middle parts squarrose and apices incurved.

Branch leaves

Large, (1.6-) 2-3.5 mm long, 0.3-0.5 mm wide, narrowly lanceolate, long acuminate, ending in acute apices, upper parts obscure, transitional parts shorter, basal parts differentiated, translucent, (1/2-)1/3 the whole leaf length, costae thin, percurrent, margins sub-entire, plane or recurved at base on one side.

Upper cells

Partly bistratose at apices, elsewhere single-layered, in conspicuous longitudinal rows, small, 6-8 µm long, 6-8(-12) µm wide, quadrate with rounded to oval lumina, thick walled, not bulging, with several small papillae per cell, marginal cells undifferentiated or smaller in one row, transitional cells short rectangular, walls unevenly thickened and smooth, lower cells smooth thorough, linear, 20-50(-60) µm long, 7-8 µm wide, very thick walled 3-5 µm thick, lumina narrow, straight or slightly sinuous in the same leaf.

Perichaetia

Conspicuous, sheathing the setae base, inner perichaetial leaves oblong to oblong-lanceolate, apices widely rounded to obtuse, hyaline, costae ending below the apices to short excurrent, cells very thick walled, linear at base to roundedoblong in upper part.

Calyptrae

Plicate, naked.

Setae

Short, 3-7 mm long, vaginulae naked.

Capsules

1.5(-2) mm long, ovoid to elliptic, smooth, rim slightly plicate, brown, erect.

Peristome

Single.

Spores

(12-25 µm) finely papillose.

REMARKS

The partly bistratose apex of vegetative leaves has been hitherto overlooked in Macromitrium leratii while this feature is important to differenciate this species from the nearly similar M. semperi or M. salakanum . Likewise, the shape of perichaetial leaves has been mistaken in Vitt & Ramsay (1985a). These authors describe and illustrate “acuminate-stoutly cuspidate acute apices” of the perichaetial leaves while the isotype and New Caledonian specimens observed exhibit constantly wide obtuse to rounded mucronate apices in sheathing perichaetial leaves which are more often oblong lanceolate.

In this way, the perichaetial leaves separate M. leratii from M. semperi which have lanceolate perichetial leaves with the apices acuminate and aristate. M. semperi was quoted from New Caledonia without any precise reference ( Vitt et al. 1995). As we could not find any sample of this species, we believe that mention of M. semperi is based on misidentifications and must be removed from the New Caledonian flora.

Conversely, M. leratii shares perichaetium characters with M. salakanum but it may be separated from by the bistratose apices and long acuminate shape of vegetative leaves, as well as the naked calyptrae.

The synonymy of M. salakanum var. majus with M. leratii was established by Brotherus (1906) who emphazised the absence of peristome in M. leratii as distinctive from M. salakanum , but we could observe some capsules with peristome, mostly caducous, in both type specimens. The invalid name Macromitrium seleniblastum Müll.Hal. m.s. is written on the specimen PC0138025, Balansa 916. Macromitrium leratii var. erectifolium is just a robust form with strongly coiled leaf apices and longer branches. The type specimen is sterile so that we cannot find distinctive feature dealing with perichaetium or sporophyte.

Macromitrium leratii is frequent at all but extreme altitudes, between 100-1200 m, relatively more frequent in the higher band of 800-1200 m. It was collected in scrublands, wet or dry forests at 100-900 m a.s.l. and up to 1200 m in tall scrublands and open cloud forests. It usually grows on bark of trunks or twigs but depauperate forms may rarely be found on rocks. The more robust plants are growing in half-light situations in scrublands, forest edges, open forests, ect.

Figures

FIG. 1. — Dry branch habits of Macromitrium Brid. (I) A, M. microstomum Hook. & Grev.; B, M. cardotii Thér.; C, M. francii Thér.; D, M. laevigatumThér.; E, M. leratii Broth. & Paris.; F, M. taoense Thér.; G, M. plicatum Thér.; H, M. pilosum Thér.; I, M. pulchrum Besch. From type specimens (B, D, F-I), from specimens Thouvenot NC881 (A), NC2379 (E), from specimen Coulerie COU85 (C). Scale bars: 1 mm.

FIG. 13. — Macromitrium leratii Broth. & Paris: A, perichaetium and sporophyte; B-E, branch leaves; F, upper cells; G, basal cells; H, I, perichaetial leaves; J, K, transverse section in apices of branch leaves;L, transverse section in upper third of branch leaf;M, perichaetial leaf apex.Drawn from isotypes PC0096510 (K, L) and PC0096497 (A); from specimens Thouvenot NC1018 (B, C, E), NC870 (D), NC2237 (H, I); Larraín 35492 (F, G, M); Müller NC210 (J). Scale bars: A, 1 mm; B-E, H, I, 1 mm; F, G, 10 µm; J-L, 20 µm; M, 100 µm.