Otoscyphus crassicaulis (Steph.) J.J.Engel, Bardat & Thouvenot

Thouvenot, Louis, 2023, A taxonomic revision of the Lophocoleaceae Vanden Berghen (Marchantiophyta) of New Caledonia, Cryptogamie, Bryologie 20 (1), pp. 1-60 : 49-50

Otoscyphus crassicaulis (Steph.) J.J.Engel, Bardat & Thouvenot

( Fig. 29 )

Cryptogamie, Bryologie 33 (3): 280 (Engel et al. 2012). — Lophocolea crassicaulis Steph. , Species Hepaticarum 6: 268 ( Stephani 1922). — Chiloscyphus crassicaulis (Steph.) J.J.Engel & R.M.Schust. , Nova Hedwigia 39: 413 ( Engel & Schuster 1984 [1985]).

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Type: New Caledonia. Franc s.n. (lecto-, G [ Mt. Mou , 1200 m, 17.VII.1909, Franc s.n., G00017607 ]!) .

FURTHER SPECIMENS EXAMINED. — New Caledonia. South Province, Dumbéa, Montagne des Sources strict nature reserve , on dead wood in mountain wet forest with Araucaria rulei , 950 m, 21.IX.2016, Thouvenot NC1992; Païta, Mt. Humboldt , on peridotite rocks in mountain scrubland with Araucaria humboldtensis, 1400 m , 1.X.2008, Thouvenot NC1730; Mt. Ouin , on dead wood in mountain wet forest, 1000-1025 m, 19.IX.2016, Thouvenot NC2098; Dzumac massif , on dead wood in mesophilous mountain forest, 915 m, 18.IX.2008, Thouvenot NC486; Yaté, base of Pic du Grand Kaori , on peridotite rock, 250 m, 22.X.2012, Thouvenot NC736; Wé Toa , on dead wood, in rain forest, 500 m, 8.IX.2019, Thouvenot NC2872 ( PC [ PC0779846 ]); Mont Dore, Mouirange , on dead wood in Nothofagus rain forest, 546 m, 16.IX.2019, Thouvenot NC2883.

DISTRIBUTION IN NEW CALEDONIA. — Fairly frequent on dead hard wood, more rarely on rocks, in various woodland habitats on ultramafic soils, from lowland photo-xerophytic forests to wet mountain forests or scrublands, at all altitudes (collected from 250 to 1400 m).

TOTAL RANGE. — Endemic to the southern ultramafic massif of New Caledonia, South Province.

DESCRIPTION

Further description and illustration in Engel et al. (2012).

Dioecious.

Habit

Plants delicate, shoots up to 0.6-1.0 mm wide; branching occasional, exclusively of ventral-intercalary type, Frullania - type branches rare; stems zig-zag in growth, markedly narrow for shoot size; leaves alternate, with basal sector vertically dorsally assurgent and defining an adaxial concavity, the leaf then strongly convex-arched, in cross section forming a ± inverted U or, with further curvature of the lobes, even a semicircle; at the base, the vertical sectors of opposing leaves fused.

Leaves

0.37-0.38 (0.40) mm long, bilobed, each leaf with dorsal base abruptly and strongly dilated resulting in a conspicuous flange of tissue extending towards shoot base at least to the level of the median sector of the leaf immediately below; leaves with a pronounced adaxial concavity toward base that is totally covered by the gently convex decurrent flange of tissue, the concavity pocket-like; the exposed, main portion of the leaf convex, narrowly elongate sub-rectangular, the sides from the base to lobe tip gently incurved, the leaves bifid to 0.40-0.45 of leaf length; lobes subparallel to ± divergent, subequal in size, long ciliform-setaceous; leaf disc 15-17 cells wide at base, the median sector 4-6 cells wide, the dorsal margin plane, entire, the ventral margin plane, with a conspicuous tooth near the base, this tooth asymmetrical, curved towards the stem and forming an orbicular mouth-like opening for the pocket-like leaf base.

Cells

Median leaf cells 25-30 µm wide, 35-50 µm long; cells of the exposed main portion of the leaf with massive trigones that are confluent or separated by narrow thin-walled places; cells in basal 4-5 rows of cells and flange with trigones minute to small; marginal cells with exposed wall notably thick; surface of disc finely striate, of lobes finely papillose.

Underleaves

Free, distant, the stem broadly exposed; disc a little wider than stem but with lobes laterally extending at least to level of sinus bases of the adjacent leaves; disc cunate, bifid nearly to base, small, with a distal row of 2-3 larger cells with the exposed wall distinctly thickened, basal to this row is a feebly dome-like cluster of c. 8 smaller, quadrate, rhizoid initials, the summit of disc truncate or (often) broadly rounded, entire, the lateral margins entire or at times with a 1-2-celled tooth, the disc margins decurrent; lobes diverging by an angle of c. 180° or nearly so, the line formed by lobes and disc apex maximally lunate to straight, the lobe shape much like those of the leaves but comprised of 1-3 biseriate tiers and a uniseriate row of 3-6 cells, the lobe margins uniformly entire.

Gametangia

Androecia terminal but becoming intercalary in position on main shoot or rather long ventral-intercalary branches, somewhat narrower than sterile sectors; bracts in 2-4 pairs, dorsally assurgent, densely imbricate, strongly ventricose in basal ± 0.5, the bracts deeply bilobed, the lobes similar to those of the leaves except shorter; antheridia solitary, the stalk not seen; gynoecia terminal on main shoot, or on short ventral-intercalary branches lacking normal vegetative leaves; bracts bifid to ± 0.35-0.5, the dorsal lobe smaller or reduced to a small rounded projection; bracteoles of innermost series somewhat smaller than bracts, symetrically bifid to ± 0.25- 0.5; perianths long exserted, 1.7-2.2 mm long, subterete toward base, obscurely trigonous above, oblong-elliptic, not or slightly narrowed toward the deeply 3-lobed mouth, the lobes subequal, free for± 0.30-0.35 the perianth length; lobes deeply bifid with several often long ciliiform processes; keelar wings common, 1-2 per perianth; calyptra extending ± 0.4 the perianth length.

COMMENTS

This small species is easily separated from all other New Caledonian liverworts by the combination of the following characters: 1) leaves rectangular with apices deeply bifid, lobes long linear; 2) dorsal leaf margins widely expanded, forming a pouch together with the underlying ventral margins of the adjacent leaves; 3) underleaves transversely elongate, bifid, with sinus at a flat angle and long linear lobes widely spreading, lateral margins very short, entire; 4) stems thin; and 5) branching nearly exclusively ventral-intercalary. As discussed by Engel et al. (2012), this species is close to Chiloscyphus but differs from that genus by the above-mentioned set of morphological traits. Notably, the underleaves of Otoscyphus crassicaulis are very unusual and resemble those found in Drepanolejeunea and Leptolejeunea (Lejeuneaceae) , while the pouches made of superimposed bases of leaves are unique in liverworts.

Following Engel et al. (2012), who described the type at G, the lectotype is formally designed here. The relationships of the genus Otoscyphus are unclear and await molecular study ( Söderström et al. 2013a).

Figures

FIG. 29. — Otoscyphus crassicaulis (Steph.) J.J.Engel, Bardat & Thouvenot: A, habit; B, shoot portion,ventral view; C, shoot portion, dorsal view showing dilated dorsal leaf bases overlapping the previous leaf ventral bases (SEM); D, gynoecium; E, leaf; F, underleaf; G, shoot cross section showing connation (c) of dilated dorsal leaf bases (ddb), the concave sector of leaf base (lb), the stem (s) and the underleaf (ul). All illustrated from the specimen Thouvenot NC486 (photos J. Bardat, drawings J.J. Engel). Scale bars: B, C, 200 µm; D, 500 µm; E-G, 100 µm.