Macromitrium pulchrum Besch. var. pulchrum

Thouvenot, Louis, 2019, A review of the genus Macromitrium Brid. (Orthotrichaceae, Bryophyta) in New Caledonia, Cryptogamie, Bryologie 20 (16), pp. 167-217 : 200-202

Macromitrium pulchrum Besch. var. pulchrum

( Figs 1I , 17 )

Annales des Sciences naturelles, Botanique, sér. 5, 18: 210 (1873).

Macromitrium pulchrum var. aristatum Thér., Revue bryologique 48: 16 (1921). — Type: New Caledonia, Franc s.n. (lecto-, designated here fide Guo in Sched. [2007] PC[PC0083721]!) syn. nov.

M. pulchrum var. densirete Thér., Revue bryologique 49: 16 (1921). — Type: New Caledonia. Mt Koghis, XI.1909, Franc s.n. lecto-, designated here fide Guo in Sched. [2007] PC[PC0083722]!) syn. nov.

TYPES. — New Caledonia. “In monte Humboldt, 1200 m alt., Balansa 2528; in monte Mou, Balansa 2980 partim” (lecto-, fide Vitt in Sched. [1983] BM[BM000982761]; isolecto-, PC[PC0137910]!; syn-, PC[PC0096501, PC0137911, PC137912, PC137913]!).

DISTRIBUTION IN NEW CALEDONIA. — Widely distributed in North and South Province.

TOTAL RANGE. — Endemic to New Caledonia.

SELECTED SPECIMENS. — New Caledonia. Province Nord, Hienghène, Mt Panié massif, between Bwa Téan and Payolé, in wet mountain forest, 1245 m, 9.X.2012, Thouvenot NC1374 (PC); Province Sud, Boulouparis, Mt Do, stunted vegetation with patches of Araucaria montana and Notofagus forests, 1000 m, 27.IX.2012, Larraín 35414; Dumbéa, Montagne des Sources, wet forest with Araucaria rulei , 950 m, 21.IX.2016, Thouvenot NC2330 (PC); Dumbéa, Koghis, along the trail from Auberge des Koghis to the summit, c. 900m, 9.IX.2001, Frank Müller NC116 (DR); Mt Humboldt, on the trail to the hut near the summit, 1400 m, 30.VIII.2003, Frank Müller NC768 (DR); Thio, Mt Ningua, stunted forest, 1120 m, 29.IX.2012, Thouvenot NC872; Païta, Mt Mou, tall mountain scrubland, on ridge, 1110 m, 17.IX.2016, Thouvenot NC2297 (PC); Yaté, Pic du Grand Kaori, tall scrubland, 363 m, 4.X.2016, Thouvenot NC2371 (PC); Parc de la Rivière Bleue, open wet forest, 680 m, 20.IX.2016, Thouvenot NC2249.

DESCRIPTION

Pseudautoicous

Dwarf male plants on leaf axis of female branches.

Plant

Medium to large, upper parts light green, sometimes reddish, or olive green, lower parts light to dark brown, creeping stems densely branched.

Branches

Thick, medium to long, (4-)7-16(-20) mm long, 1.5-2 mm wide, straight to curved, simple or furcate, when dry usually unevenly curly, not funiculate, with leaves erect, individually twisted flexuous, carinate, the apex incurved to circinate, exposed by the margins, when moist erect to patent, usually little recurved or straight.

Branch leaves

Large, 2.5-4(-4.5) mm long, 0.4-0.8 mm wide, lanceolate in outline, laminae usually ligulate from a wider basal part ovate to oblong, the apex narrowly obtuse, mucronate to short aristate, in a few cases lanceolate acuminate, upper part opaque, basal translucent part occupying 1/3-1/5 the leaf length, aristae if any less than 0.2 mm long, costae medium thick, excurrent, margins papillose crenulate, plane or recurved on one side near base.

Upper cells

Single-layered, of various sizes ranging (7-)10-20(-30) µm long, (7-) 10-12 mm wide, quadrate, rounded to oblong elliptic, thick walled, bulging, the external walls strongly protruding, rounded to conical with small papillae simple to furcate, the cells roughly aligned, marginal cells smaller in one row, transitional part usually short, transitional cells short rectangular, thick walled, walls irregular, porous nodulose, with single rounded papillae, lower cells rectangular elongate to linear, 20-55(-80) µm long, 7-10 µm wide, very thick walled, walls 2.5-3.5 µm wide, lumina straight, narrow, single papillae scarce, low to high rounded.

Perichaetia

More or less visible, erect, loosely sheathing the seta bases, perichaetial leaf sizes and papillae similar to the vegetative ones, lanceolate, mostly acuminate or acute, aristate, translucent thorough.

Calyptrae

Naked.

Setae

Long, (15-)18-30(-35) mm long, thin, flexuous, vaginulae naked.

Capsules

1.5-2 mm long, elliptic to narrowly oblong, smooth, rims plicate, brown, small, erect to incurved.

Peristome

Absent or reduced to a papillose membrane.

Spores

Anisomorphic (12-)15-32(-37) µm.

REMARKS

Macromitrium pulchrum is easily recognized by: 1) medium to large size with long setae; 2) dense branching with simple branches, curly when dry, with leaves erect, individually twisted to curved apices exposed by the margins; 3) large branch leaves ligulate to lanceolate, with a widened basal part ovate oblong; 4) upper cells uneven in size, bulging because of the strongly protruding external walls, pluripapillose; 5) basal cells linear with very thick walls, straight narrow lumina and scarce single papillae; 6) calyptrae naked; and 7) capsules narrowly oblong, sub-cylindric, with brown erect plicate rims and peristome lacking or reduced to a short membrane.

Apart from the Pulchrum group, none of the other New Caledonian species exhibit such combination of characters, most of them being smaller species with smaller setae.

Other large species like Macromitrium leratii , M. laevigateum or M. salakanum have short setae and different leaf shape.

For differences with species of the Pulchrum group: Macromitrium cardotii , M. rufipilum and M. pulchrum var. neocaledonicum , which also are large plants and possess large setae, see comments in the corresponding paragraphs.

The varieties described by Thériot (1921a) show too minor differences to be kept here: Macromitrium pulchrum var. densirete more closely resemble M. pulchrum var. neocaledonicum (see below) but with the branch habit of M. pulchrum var. pulchrum when wet. M. pulchrum var. aristatum has leaves like the type variety but longer excurrent costae and longer branches which are variable intra-specific characters in the Pulchrum group. The type in PC has long branches, simple or fasciculate, up to 22 mm long, setae 18-20 mm long, basal cells with single scattered or ranked papillae. So, M. pulchrum var densirete and var. aristatum may be included in the variability of the type variety.

Macromitrium pulchrum is one of the most frequent species in New Caledonia, growing on trunks in wet mountain forests above 400 m, rarely at 300- 400 m. It mostly inhabits cloud forests on ridges and summit up to 1400 m.

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. 17. — Macromitrium pulchrum Besch. var. pulchrum.: A, capsule; B, dwarf male plant; C-F. branch leaves; G, upper cells in side view; H, upper cells; I, basal cells; J-L, branch leaf apices of three varieties; M, transverse section in top quarter of branch leaf. Drawn from the isotype PC0096501 (A, C, I, L), from the lectotype of M. pulchrum var. densirete Thér. (E, K, M), from the lectotype of M. pulchrum var. aristatum Thér. (F, J), from the specimens Thouvenot NC2226 (B), NC2247 (G, H), NC2252 (D). Scale bars: A, 1 mm; B, 500 µm; C-F, 1 mm; G-I, 10 µm; J-L, 100 µm; M, 20 µm.