Macromitrium francii Thér.

Thouvenot, Louis, 2019, A review of the genus Macromitrium Brid. (Orthotrichaceae, Bryophyta) in New Caledonia, Cryptogamie, Bryologie 20 (16), pp. 167-217 : 182-184

Macromitrium francii Thér.

( Figs 1C , 7 )

Bulletin de l’Académie internationale de Géographie botanique 17:

308 (1907).

M. contractum Thér. , Bulletin de l’Académie internationale de Géographie botanique 18: 253 (1908). — Type: New Caledonia, Mt Dzumac. (lecto- fide Vitt [1980]: New Caledonia, Mt Dzumac, 700 m, avril 1905, Le Rat s.n. [not Franc s.n.] [Herbarium Thériot n°66] PC[PC0137649]!; iso-, PC[PC0137650, PC0137651]!) syn. nov.

TYPE. — New Caledonia. 1906, Franc s.n. (Renauld missit) (lecto-, designated here: New Caledonia, 1906, Franc s.n. [Herbarium Bonati ex herbarium Thériot] PC [ PC 0096496]!; iso-, PC [ PC 0738574!, PC 0137702!, PC 0137704!, PC 0137705] p.p.!)

DISTRIBUTION IN NEW CALEDONIA. — Macromitrium francii is frequent in North and South Province, in areas with various geologic substrates including calcareous ones, on barks and twigs, more than 1 m above the ground, from lowland up to 1200 m in scrublands, riparian forest, dry or wet or cloud forests.

TOTAL RANGE. — Endemic to New Caledonia.

SELECTED SPECIMENS. — New Caledonia. Province Nord, Poindimié, Pömwaga, 350 m, 11.X.2012, Thouvenot NC924; Hienghène, La Gùèn (Panié), 550 m, 8.X.2012, Larraín 35922; Ponérihouen, Aoupinié, 1000 m, 2.X.2012, Larraín 35585. Province Sud, vicinity of Nouméa, 1907, Franc s.n. PC0137701 (PC); Nouméa, 1908, Franc s.n. PC0096496 (PC); Païta, trail to Dzumac massif, 915 m, 18.IX.2008, Thouvenot NC290 (PC); Thio, Mt Ningua, 1120 m, 29.IX.2012, Thouvenot NC873; Yaté, Madeleine falls, 240 m, 8.X.2015, F. Müller NC265 (DR); Rivière Bleue Natural Park, 6.IX.2001, F. Müller NC290 (DR).

DESCRIPTION

Pseudautoicous

Dwarf male plants on leaf axis of female branches.

Plant

Medium, upper parts light green, lower parts olive green to light brown, creeping stems densely branched.

Branches

Thin, small to medium, (2-)5-8(-10) mm long, (0.5-) 0.8-1 mm wide, straight to slightly 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 margin, when moist erect-patent, the apices usually little incurved.

Branch leaves

Small to medium, (0.75-) 1-1.5 mm long, (0.22-)0.3-0.4(- 0.5) mm wide, oblong to lanceolate in outline, laminae ligulate to lanceolate from a wider basal part ovate to oblong, the apices acute to obtuse and apiculate or mucronate, upper parts obscure to translucent, basal parts undifferentiated, costae thick, ending in the apices or apiculi, margins papillose crenulate, plane.

Upper cells

Single-layered, small, rounded to oval, (7-) 10-12 mm wide, thin walled, bulging, with 3-5 small papillae per cell, the cells roughly aligned, marginal cells smaller in one row, usually oblate, transitional cells reaching the base, oval to short rectangular, thick walled, with single rounded papillae, lower cells few, rectangular, 15-35 µm long, 5-10 µm wide, thick walled, lumina relatively wide, lower cells with single rounded papillae scarce but present on most of the leaves.

Perichaetia

Inconspicuous, perichaetial leaves similar to the vegetative ones, someone more triangular in outline.

Calyptrae

With dense and erect hairs.

Setae

Very short, 1-1.5(-2) mm long, erect, vaginulae with long hairs reaching the capsule.

Capsules

Short exserted, 1(-1.2) mm long, ovoid to elliptic, smooth, rims plicate, brown, small, incurved.

Peristomes

Single.

Spores

Anisomorphic 12-35 µm.

REMARKS

As stated above, Macromitrium francii is close to the other species brought together in the Francii group. When fertile, the very short setae of M. francii and the long hairy vaginulae are distinctive but vegetative parts of the plants could be confused with species with short or medium curly branches as M. involutifolium var. involutifolium , M. ligulaefolium and M. hemitrichodes var. sarasinii . They can be separated from as follow:

Macromitrium involutifolium var. involutifolium has longer leaves, 2-3 mm long, and branches, up to 15 mm long,

Macromitrium ligulaefolium has thicker branches, 1.5 mm wide, longer leaves, 1.5-2.7 mm long, narrowly ligulate to linear with conspicuous basal parts made of rectangular-elongate to linear cells, the third by longer lanceolate acuminate leaves, 1.6-2.4 mm long, strongly carinate and incurved in upper part.

Macromitrium hemitrichodes var. sarasinii has longer leaves, 1.6-2.7 mm long, with many distinctive basal cells.

For the lectotypification, we first looked for pockets of the original Thériot herbarium in PC but we could not find amongst them any part of the original collection made by Franc in 1906. The single original pocket of M. francii from Thériot herbarium at PC contains specimens gathered in 1907. Thériot (1907) pointed out that the specimens collected by Franc were sent to him by Renauld, so we could observe many isotypes from the Renauld herbarium, unless it could be certain that Thériot saw them. Therefore, we prefer to consider parts sent by Thériot to bryologist fellows and to select as lectotype an isotype from the Bizot herbarium which is copious, fertile and homogeneous, while the others are mixed with different Macromitrium species.

Macromitrium contractum was first described by Thériot (1908), then reduced to synonymy with M. noumeanum (synonym of M. involutifolium ) by the same author ( Thériot 1921b) who finally reinstate it as a distinct species ( Thériot 1929). The lectotype was designated by Vitt (1980) as follow “ Nouvelle-Calédonie: Mont Dzumac récoltée par M. Franc”, herbier Thériot. But the determinavit label let at PC do not have this precision and is annexed to a pocket extracted from Thériot’s herbarium with the same locality name but collected by Le Rat. The handwritten abreviation “fig.”, and the successive delated mentions “ Macrocoma contractum n.sp. ” and “ noumeanum ss forma” are arguments in favour of an original specimen used by Thériot to define this species. In addition, another pocket (PC0137651) including a duplicate bears the printed mention “leg. Franc” who was deleted and replaced by “Le Rat” handwritten by Thériot, that could explain the confusion of the original diagnose in the collector name, repeated by Vitt (1980). The examination of the lectotype showed resemblance with M. francii as well as with M. noumeanum . But the differences with M. francii are relatively low and quantitative, the branches, leaves and setae being longer but not so much, respectively 10-20 mm, 1.5-1.7(-1.9) mm and 1.8-2 mm, while the differences with M. noumeanum are more important: leaves exhibiting a different shape, in addition, strongly papillose especially in upper part and the elliptic capsules being shorter. Here we consider M. contractum as a form of M. francii .

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. 7. — Macromitrium francii Thér.: A, dry branch with sporophyte; B-F, branch leaves; G, branch leaf apex; H, upper cells; I, transitional and marginal cells; J, L, basal cells; K, basal and marginal cells. Drawn from the isotype PC0096496 (G, H, J), from the specimen Franc PC0137701 (D, E, L), from the specimens Thouvenot NC1007 (A, I, K), NC2264 (B, C, F). Scale bars: A, 1 mm; B-F, 500 µm; G, 100 µm; H-L, 10 µm.