Lophocolea bidentata (L.) Dumort

Thouvenot, Louis, 2023, A taxonomic revision of the Lophocoleaceae Vanden Berghen (Marchantiophyta) of New Caledonia, Cryptogamie, Bryologie 20 (1), pp. 1-60 : 40-41

Lophocolea bidentata (L.) Dumort

( Fig. 23 )

Recueil d’Observations sur les Jungermanniacées 1: 17 ( Dumortier 1835). — Jungermannia bidentata L., Species Plantarum: 1132 ( Linnaeus 1753).

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Type: Great Britain. Zollinger 3613 ( OXF), not seen.

SPECIMEN EXAMINED. — New Caledonia. South Province, Humboldt Massif , 1200 m, on rocks, 30.IX.2008, Thouvenot NC2490 ( PC [ PC0779842 ]) .

DISTRIBUTION IN NEW CALEDONIA. — Newly reported, its distribution in New Caledonia is under-documented.

TOTAL RANGE. — Subcosmopolitan.In the austral Indo-Pacific region, Lophocolea bidentata is reported from the Mascarenes ( Ah-Peng & Bardat 2005), Australia ( McCarty 2006 as Chiloscyphus latifolius [Nees] J.J.Engel & R.M.Schust.), New Zealand ( Glenny 1998 as C. chlorophyllus [Hook.f. & Taylor] Mitt.), Java ( Söderström et al. 2010 as C. coadnatus [Hook f.&Taylor] Mitt.) and New Guinea ( Piippo 1985).

DESCRIPTION

Based on the New Caledonian specimen.

Habit

Plant medium sized, in loose mats of interwoven stems with many branches, lateral-intercalary; main stems 0.20 mm wide, shoots complanate, main shoots 2.00- 2.50 mm wide, branches variously narrower, sometimes strongly attenuated; leaves distichous, spreading at right angle, plane, contiguous to slightly imbricated, not connate dorsally, brownish in older main shoots.

Leaves

Ovate to oblong-rectangular, 1.20-1.40mm long, 0.75-0.90 mm wide, margins smooth, entire, apices truncate, bilobed, lobes triangular at base with acute to piliform apices 1-3 cells long, sinus wide,lunate to right-angled, branch leaves contiguous to remote, smaller, with lobes narrower and piliform lobe apices longer.

Cells

Leaf cells rounded to oval, 25-30 µm x 25-45 µm, with small to large nodulous trigones.

Underleaves

Deeply bifid, disc small, 3 cells high at mid-insertion, 0.15- 0.20 mm long, 0.20-0.25 mm wide, lobes narrowly lanceolatelinear, piliform apices 3-7 cells long, overall size 0.35-0.50 mm long, 0.40-0.60 mm wide, circa 2 times the stem width, not connate to the ventral margins of the leaves.

Gametangia

Not seen.

COMMENTS

This species is newly reported from New Caledonia. Its wide range might be further extended since several austral species have already turned to be synonyms (see above total range) and many countries of the Pacific region are still understudied. The New Caledonian specimen is sterile and shows a large variation in shoot width. It somewhat differs from typical L. bidentata only in the small to medium-sized trigones. The material differs from L. bispinosa , a New Zealand species which has similar overall shape and conspicuous trigones but possesses heterogeneous areolation with larger cells scattered inside the lamina and along the margins. Furthermore, the latter species has a deeper sinus between longer piliform lobes and leaf margins with ciliate processes.

The rarity of Lophocolea bidentata in New Caledonia could be linked to the ecological conditions since it was found in one of the highest localities of the island where it grows with Cryptolophocolea subcostata (Steph.) Thouvenot , Telaranea bisetula (Steph.) E.O.Campb. , Trichocolea pluma (Reinw., Blume & Nees) Mont. and Cheilolejeunea trapezia (Nees) R.M.Schust. & Kachroo.

Figures

FIG. 23. — Lophocolea bidentata (L.) Dumort.: A, main shoot, ventral view; B, secondary shoot, ventral view; C, leaf cells; D, G, underleaves; E, leaf apex; F, leaf. All drawn from Thouvenot NC2490. Scale bars: A, B, 1 mm; D-G, 200 µm; C, 50 µm.