Macromitrium hemitrichodes var. sarasinii (Thér.) Thouvenot 2019

Thouvenot, Louis, 2019, A review of the genus Macromitrium Brid. (Orthotrichaceae, Bryophyta) in New Caledonia, Cryptogamie, Bryologie 20 (16), pp. 167-217 : 184-186

Macromitrium hemitrichodes var. sarasinii (Thér.) Thouvenot , comb. nov.

( Figs 2A , 8)

BASIONYM. — Macromitrium sarasinii Thér. , Nova Caledonia- Forschungen in Neu-Caledonien und auf den Loyalty-Inseln, B. Botanik 1: 25 (1914).

TYPE. — New Caledonia. Mt Canala, alt. 650 m, 1911, Sarasin 334. (lecto-, designated here PC [ PC 0096515]!).

DISTRIBUTION IN NEW CALEDONIA. — Macromitrium hemitrichodes var. sarasinii is only known from two specimens collected before 1952 in Province Nord.

TOTAL RANGE. — This variety is endemic of New Caledonia.

SELECTED SPECIMENS. — Australia. Macromitrium hemitrichodes North South Wales, Mt Lindsay, IX.1900, W. Forsyth, com. Brotherus PC[PC0659543]; Java, sin. loc., s.d., Korthals s.n., Herb. Lugd. Batav., PC[PC0659544].

New Caledonia. M. sarasinii Province Nord, corticolous on Tapeinosperm a, mesophilous forest, ridge between the two Télème branches, west to Mt Colnett, c. 850 m, 11.IX.1951, Hürlimann 2928, PC [ PC 0659540].

DESCRIPTION

Sexual condition

Unknown.

Plant

Small, orange brown in herbarium, creeping stems densely branched.

Branches

Thick, short, 3-6 mm long, simple, when dry strongly curly, leaves erect individually twisted, carinate, the apex incurved to circinate, exposed by the margin, when moist spreading incurved.

Branch leaves

Medium to large, 1.6-2.7 mm long, 0.4-0.7 mm wide, strongly carinate, laminae lanceolate to triangular above the wider oval bases, upper parts opaque, basal parts translucent, 1/6-1/4 the total leaf length, apices acuminate to acute, costae ending below the apices to excurrent in a mucro, margins entire.

Upper cells

Single-layered, quadrate rounded, 6-10 µm wide, bulging, very thick walled with several small papillae, marginal cells sometimes smooth in one rank, transitional cells becoming gradually longer, from hexagonal to short rectangular, walls unevenly thickened, lumina narrowly rhomboidal, with single rounded papillae, lower cells rectangular elongate, 25-50 µm long, 7 µm wide, very thick walled, lumina narrow, straight to wavy, single papillae numerous, eventually displayed on plicae, low to high rounded.

Perichaetia

Short, inconspicuous, loosely erect, not sheathing, perichaetial leaves smaller than the vegetative ones.

Calyptra

Not seen.

Setae

Short, 5-6 mm long, thin, vaginulae with short inconspicuous paraphyses.

Old capsules

Elliptic, strongly 8-plicate, rims plicate erect.

Peristome

Not seen.

C E A D F B G H K J I

REMARKS

Macromitrium hemitrichodes var. sarasinii is characterized by: 1) very short but thick branches which are strongly curly when dry, the leaves loosely erect twisted with curved to circinate apices; 2) large branch leaves lanceolate above wider oblong bases; 3) very thick walled cells, the upper ones small, quadrate rounded, strongly bulging, pluripapillose, the basal ones elongate with narrow lumina straight or slightly sinuous, with numerous single papillae, intermediate cells numerous; 4) medium setae, mostly 6 mm long; and 5) elliptic capsules 8-plicate when dry.

We agree whith Thériot (1914) who stressed the similitude of this plant with the Australian Macromitrium hemitrichodes . Many features are identical, especially size and shape of branch leaves and their general habit in dry condition, most areolation characters, sporophyte, ect. Thériot related primarily the differences to quantitative assessment which have a low significance at species rank: more robust plant, shorter setae, larger leaves with relatively longer and less papillose basal parts, costae ending above the apices, ect. We reviewed the type specimen of M. sarasinii and found that all the sizes selected by Thériot to characterize his new species were included in the variability of M. hemitrichodes , according to the description by Vitt & Ramsay (1985) and our observation of M. hemitrichodes specimens. Only basal cells length, reaching 50 µm long, and leaf length, 1.6-2.7 mm long, can differentiate M. sarasinii . As in the case of Macromitrium aurescens var. caledonicum , these differences with the type variety are restricted to quantitative characters and, in our opinion, M. sarasinii is at most a variety of M. hemitrichodes . Further collections in New Caledonia and surrounding regions will allow to clarify this status. The status of Macromitrium hemitrichodes var. hemitrichodes , which is said endemic to eastern Australia, then could need ammendment. In addition, a sample labelled M. hemitrichodes and collected in Java by Korthals (around 1850) (PC), shows intermediate sizes in basal cell and leaf lengths, but longer branches, up to 20 mm long, and needs further investigations on more material from Java.

Figures

FIG. 2. — Dry branch habits of Macromitrium (II) A, M. sarasinii Thér.; B, M.humboldtense Thouvenot & Franck Müll.; C, F, M. panduraefolium Thouvenot; D, M. larrainii Thouvenot & K.T.Yong; E, M. tongense Sull.; G, M. subvillosum Broth. & Paris; H, M. rufipilum Cardot; I, M. aurescens var. caledonicum (Thér.) Thouvenot. From type specimens (A-D, F, H, I), from specimens Müller NC755 (E), NC764 (G). Scale bars: 1 mm.