Heteroscyphus kanakensis Thouvenot & Engel, 2021

Thouvenot, Louis, 2023, A taxonomic revision of the Lophocoleaceae Vanden Berghen (Marchantiophyta) of New Caledonia, Cryptogamie, Bryologie 20 (1), pp. 1-60 : 30-32

Heteroscyphus kanakensis Thouvenot & Engel

( Fig. 16 )

Nova Hedwigia 112: 166, 1-2 ( Thouvenot & Engel 2021).

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Type: New Caledonia. South Province, Yaté, Rivière Bleue Natural Park , La Tranchée , on tree bark in river side, ultramafic massif, 200 m, 19.X.2016, Thouvenot NC2487 (holo-, PC [ PC0779856 ]; iso-, F, hb. Thouvenot).

FURTHER SPECIMENS EXAMINED. — New Caledonia. North Province, Pouébo, Diahoué , on wet rocks in the creek Wé Wayat , 400 m, 21.IX.2019, Thouvenot NC2771; NC2829; Touho, Pombei , Tiwaka valley , on rocks in high bush of Melaleuca quinquenervia (Cav.) S.T.Blake and Gymnostomum sp. , volcano-sedimentary massif, 415 m, 12.X.2016, Thouvenot NC2488 (para-, NOU, F); South Province, Lac Chakéké , on silt-laden deposits on barks along a temporary creek, in gallery forest, 411 m, 4.X.2019, Thouvenot NC2727 (para-, PC [ PC0779848 ], F, hb. Thouvenot).

DISTRIBUTION IN NEW CALEDONIA. — In a few localities at low altitudes in North and South Province, from 200 to 400 m. It grows on various substrates, barks, rocks, or silt laden deposits on trunks along creeks and was found in wet forest in sedimentary massif as well as gallery forest inside ultramafic scrubland.

TOTAL RANGE. — Endemic.

DESCRIPTION

Further description and illustrations in Thouvenot & Engel (2021).

Dioecious.

Habit

Plants rather rigid, fragile, pale green, pale brown in older sectors, somewhat water repellent, the shoots to 3 mm wide when flattened; stems narrow for plant size; leaves subopposite, typically obliquely dorsally assurgent (the basal sector of dorsal half angling upward at c. 45° from stem and never facing dorsal base of opposing leaf), the leaves densely imbricate, free dorsally; leaves somewhat longitudinally undulate in dorsal aspect, moderately convex in dorsal sector, moderately abaxially concave in ventral sector, the concave ventral sector overlayed by the convex dorsal half of the leaf immediately above.

Leaves

Subsymmetrical, up to 1.60 mm long, ovate and up to c. 1.3 times longer than wide; apex broadly rounded, entire; margins broadly and ± evenly arched, entire to faintly crenulate, the dorsal margin not decurrent.

Cells

Leaf cells with nodulose trigones separated by narrow, thinwalled places, the trigones sometimes confluent, the median leaf cells uneven in size, 8-12 µm wide, 10-20 µm long, somewhat larger near the base; surface with a granular, scurffy appearance throughout.

Underleaves

4-5 times the stem width when flattened, symmetrically connate with the leaves on both sides, the connate portion 1-3 cells wide; underleaves imbricate, rotund to oblate, 0.50- 0.80 mm long, 0.50-0.90 mm wide, usually 1.15 times wider than long; apex bifid to c. 0.35, the lobes ± parallel to weakly divergent, widely triangular, acute to stoutly acuminate, the sinus narrowly to widely rounded; lamina margins on both sides with a large tooth, the lamina margins otherwise entire or with 1-2(3), smaller, accessory teeth below.

Gametangia

Gynoecia on short lateral-intercalary, leafless branches; bracts deeply laciniate-lobed, the margins toothed toward the base; bracteole deeply bifid, the margins sparsely laciniate or toothed; perianths seen only in juvenile state, cyathiform, eplicate, the mouth lobulate, the lobules ending in a uniseriate row and with small teeth below; androecia small for plant size, nearly hidden by leaves in dorsal aspect, fully exposed in ventral aspect, on abbreviated, determinate, lateral-intercalary branches, the androecia usually strongly arched, with 2-8 pairs of bracts, the bracts dorsally convex, strongly ventricose, halfspherical-helmet shaped, the dorsal pocket scarcely defined, the inflated upper faces of the bracts elevated above the level of the axis so that the spike is furrowed, the apices rounded to retuse, entire, the margins sparingly crenulate by projections of a single cell, with slime papillae few to numerous; bracteoles oblong, short bifid, the margins entire, rarely with a small tooth, with slime papillae few to numerous; antheridial stalk biseriate.

COMMENTS

Heteroscyphus kanakensis superficially resembles H. menziesii (Mitt.) J.J.Engel described from New Zealand ( Engel & Glenny 2019). They share many characters, among them: 1) a habit with light colour, medium size 2-3 mm wide when flattened, canaliculate shoots with subopposite leaves more or less assurgent; 2) rounded leaves densely imbricate, longitudinally undulate; 3) large trigones, cells bulging so that the leaf surfaces are bumpy; 4) bifid rounded underleaves, relatively large, connate on both sides with the nearest leaves. However, Heteroscyphus kanakensis is characterized by: 1) rather rigid shoots; 2) leaves obliquely assurgent, the dorsal insertion of both opposite leaves separated by one file of stem cells; 3) leaf margins and apices entire; 4) underleaves 4-5 times the stem, with two triangular acute teeth at apices and 1-3 smaller teeth on both lateral margins; and 5) androecia longer, in arched spikes of 2-8 pairs of bracts, conspicuous in ventral view. In contrast, typical forms of H. menziesii has soft and spongy shoots, leaves vertically assurgent, the dorsal base facing the dorsal base of the opposite leaf, dorsal leaf margins conspicuously connate by way of a laminar strip several cells wide, leaf apices 2-toothed, underleaves up to 3 times the stem width, margins with many dentiform or ciliiform teeth, androecia shorter with 1-2 pairs of bracts, hidden in both ventral and dorsal views ( Engel & Glenny 2019).

For differences from the similar species Heteroscyphus confertus , see the comparison under that species.

Figures

FIG. 16. — Heteroscyphus kanakensis Thouvenot & J.J.Engel: A, leaf pair and attached underleaf; B, portion of shoot (habit in dorsal view); C, median leaf cells; D, H, leaves; E-G, I, L, M, underleaves; K, marginal cells at leaf apex; J, stem transverse section; O, U, male bracteoles; P, male bract; T, androecium habit (ventral view); N, shoot transverse section showing dorsally assurgent antical part of leaves; V, top part of perianth (expanded); Q, S, female bracteoles; R, gynoecium habit (ventral view); W, X, female bracts. A, F, L, drawn from the paratype Thouvenot NC2488; B, J, N-X, from the holotype; C, D, E, G, H, I, K, M, from the paratype Thouvenot NC2727. Scale bars: A, D-I, Q, S, T, V-X, 500 µm; B, R, 1 mm; C, J, K, 20 µm; L, M, 200 µm; N-P, U, 100 µm.