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

description: Heteroscyphus parapilistipulus (Thouvenot) Thouvenot, comb. nov.
(Fig. 17)
Chiloscyphus parapilistipulus Thouvenot, Candollea 75: 286, figs 1; 2 (Thouvenot & Price 2020).
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Type: New Caledonia. South Province, La Foa, Dogny plateau, on wet rock in the creek Dogny, 918 m, Thouvenot NC2451 (holo-, PC [PC0763751]!; iso-, author’s private herbarium; para-, G [New Caledonia. “ In jugo Dogny (1050 m)”, VII.1909, L. Le Rat s.n., G00051491!, G00051492!]; PC [PC0102406!, PC0150609!]; REN s.n.!).
FURTHER SPECIMENS EXAMINED. — New Caledonia. North Province, St Paul, Pwâ Yogac river, on damp emerged rock in a creek bed, 438 m, 24.IX.2019, Thouvenot NC2786.
DISTRIBUTION IN NEW CALEDONIA. — Scattered in North and South Provinces, rarely collected.
TOTAL RANGE. — Endemic.
DESCRIPTION
Further description and illustrations in Thouvenot & Price (2020).
Dioecious.
Habit
Plants olive green, medium to large, shoots up to 4.5 mm wide; shoots often attenuated with leaves becoming progressively smaller toward shoot tops; branching latero-ventral; leaves spreading at a wide angle from the stem, slightly convex, alternate, not dorsally decurrent.
Leaves
Normal leaves 1.40-2.00 mm long, 0.90-1.50 mm wide, oval-oblong, transversally to obliquely truncate; apices usually concave with a single acute tooth at both distal angles, sometimes shallowly bifid with short lobes widely triangular, minutely apiculate, some leaves with rounded apices; lateral margins entire and smooth.
Cells
Leaf cells hexagonal, isodiametric to slightly elongate, 44-66 µm long, 25-52 µm wide, walls thin without trigone.
Underleaves
Small, not or hardly wider than the stem, overall oval, deeply bifid, disc wider than long, 3-4 cells high, insertion line semi-circular, lateral margins with a small obtuse tooth on both sides, sometimes linear, apices with sinus lunate, both lobes erect or crescent shaped, narrowly lanceolate acuminate to linear.
Gametangia
Gametangia of both sexes terminal on short leafless branches, lateral ventral; only juvenile gynoecia seen, bracts oval, 1.20- 1.80 mm long, bifid, lobes ovate acute, a lanceolate segment usually developed on the upper part of a single lateral margin otherwise entire or with rare small teeth, bracteole deeply bifid, 1.50 mm long, lobes narrowly lanceolate, more or less convergent, margins entire, perianth 2.0- 2.5 mm long, cyathiform, smooth, tri-lobate, lobes deeply laciniate; androecia in thin spikes of ± 6 pairs of ventricose bracts.
COMMENTS
This plant resembles Lophocolea convexula (synonym: L. pilistipula, see below) but differs from the latter species by: 1) a larger size of shoots, leaves and cells; 2) the absence of trigones; 3) outer cell walls flat thus leaf margins smooth, not crenulate; 4) a dioecious condition; 5) gynoecia on very short branches without vegetative leaves; and 6) androecia in spikes of six pairs of bracts on ventral lateral abbreviated branches. Among the three syntypes of L. pilistipula Steph. at G, only the tiniest specimen, from Isle of Pines (G00112487), matches the morphological features of this species. The other two, both from Dogny (G00051491 and G00051492) are sterile, have larger dimensions and belong to the new species Heteroscyphus parapilistipulus (Thouvenot) Thouvenot, comb. nov. with shoots being 3.00- 4.50 mm wide, leaves 1.40-2.00 mm long and 0.90-1.50 mm wide near base, and cells 44-66 µm long and 33-50 µm wide. Furthermore, the leaf margins are smooth instead of crenulate. Duplicates of these collections are in PC. The initial placement of the species in Chiloscyphus was warranted by the discovery of a female plant (Thouvenot & Price 2020), but then, another specimen collected in North Province (Thouvenot NC2786) has proven to be male, with a few old antheridia of heteroscyphoid type hidden amongst oldest parts of shoots. They consist of elongate spikes of six pairs of bracts at the end of short ventral lateral branches of limited growth, despite some vegetative leaves were seen at the end of a single spike. The combination of both sexual characters brings evidence for placing this species in the genus Heteroscyphus.
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 32, DOI: 10.5252/cryptogamie-bryologie2023v44a1, http://zenodo.org/record/7822577