Heteroscyphus caledonicus Schiffn.
Creators: name: Thouvenot, Louis
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Plantae
Marchantiophyta
Jungermanniopsida
Jungermanniales
Lophocoleaceae
Heteroscyphus
Heteroscyphus caledonicus

description: Heteroscyphus caledonicus (Steph.) Schiffn.
(Fig. 7)
Oesterreichische Botanische Zeitschrift 60:172 (Schiffner 1910). — Chiloscyphus caledonicus Steph., Species Hepaticarum 3: 216 (Stephani 1907).
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Type: New Caledonia. Deplanche s.n. (holo-, G [G00069500]!).
FURTHER SPECIMENS EXAMINED. — New Caledonia. South Province, Mé Areimbo, X.1909, L. Le Rat 341 (G); Mts. Koghis, in forest, 300 m, 4.IV.1909, Franc s.n. (G); North Province, Touho, Massif des Lèvres, Tipelei upper valley, on sedimentary rocks, 315 m, 12.X.2012, Thouvenot NC2426 (PC [PC0712113]).
DISTRIBUTION IN NEW CALEDONIA. — Reported from South Province according to the labels of historic collections, but recently found only in North Province, in remote places of the north-eastern coastal massifs, at low elevations.
TOTAL RANGE. — Endemic.
DESCRIPTION
Dioecious.
Habit
Plants fragile, minute to medium sized, very variable in width, usually up to 3.00 mm, but many shoots less than 1 mm wide; leaves subopposite, horizontally spreading at right angle, slightly imbricate to contiguous, dorsally free, the homologous leaves separated by a strip of 3-4 epidermal cells on the dorsal midline of the stem; stems 0.15-0.20 mm wide.
Leaves
1.10-1.40 mm long, 0.85-1.20 mm wide, rectangular to oblong, apices truncate to widely triangular, with a spinose tooth on each three angles, teeth at most 3 cells long, dorsal and ventral margins entire.
Cells
Leaf cells hexagonal, 60-70 µm long, 40-50 µm wide, longer near bases, without trigones or trigones small and acute.
Underleaves
Inserted in an inverted U, narrowly decurrent on one or both sides, sometimes narrowly connate to the ventral bases of the nearest leaves, otherwise free and set away from the corresponding leaves to the middle of the next ones; underleaves wider than long, 0.30-0.40 mm long, 0.40-0.60 mm wide, usually 1-2 times the stem width, bifid rarely trifid, discs narrowly transverse, only two cells high at sinus insertion, lobes linear, above 2-celled bases or not, erect, sinus widely lunate or flat, lateral margins with one to three linear segments, lobes and segments fragile, often broken, sometimes furcate.
Gametangia
Gynoecia at the end of short leafless lateral-intercalary branches, bracts asymmetrically bifid, laciniate-toothed, bracteoles sym - metrically bifid up to mid length, margins toothed; perianths cyathiform, deeply trilobed, lobes ovate with laciniate-toothed margins; androecia not seen.
COMMENTS
Heteroscyphus caledonicus can be distinguished from the variable H. grandiflorus by: 1) leaves mainly oblong-rectangular instead of ovate; 2) leaves contiguous or narrowly overlapping instead of imbricate; 3) apical teeth spinose, shorter, not ending in piliform tips; and 4) cells with small trigones, if any.
The type in G is sterile and scanty, but fresh material collected by the author contained gynoecia, which are described here for the first time and are similar to those of Heteroscyphus and Chiloscyphus. The species is provisionally maintained in Heteroscyphus pending the discovery of androecia. Like H. etesseanus and H. cornutistipulus (see below) as well as further Heteroscyphus species in Australasia (Engel 2015), H. caledonicus lacks typical vegetative characters of Heteroscyphus such as connate underleaves, large trigones and opposite leaves.
description: Published as part of Thouvenot, Louis, 2023, A taxonomic revision of the Lophocoleaceae Vanden Berghen (Marchantiophyta) of New Caledonia, pp. 1-60 in Cryptogamie, Bryologie 20 (1) on page 16, DOI: 10.5252/cryptogamie-bryologie2023v44a1, http://zenodo.org/record/7822577