Chiloscyphus parapilistipulus Thouvenot, 2020

Thouvenot, Louis & Price, Michelle J., 2020, Chiloscyphus parapilistipulus (Lophocoleaceae), a new species of liverwort from New Caledonia, with the typification of Lophocolea pilistipula, Candollea 75 (2), pp. 285-289 : 286-287

Chiloscyphus parapilistipulus Thouvenot , sp. nov. ( Fig. 1–2 ).

Holotypus: NEW CALEDONIA. Prov. Sud: La Foa, Dogny plateau , on wet rock in the creek Dogny , [165°52'06"E 21°37 '02"S], 918 m, 26.IX.2016, Thouvenot NC2451 ( PC [ PC0763751 ]! ; iso-: Herb. Thouvenot!).

Chiloscyphus parapilistipulus Thouvenot resembles Lophocolea pilistipula Steph. but differs by its dioicous condition with terminal gynoecia on highly abbreviated ventro-lateral intercalary branches, larger size with shoots up to 5 mm wide, leaf apices lunate to shortly bifid, entire and smooth leaf margins and leaf cells without trigones.

Plants olive green, medium to large, shoots up to 4.5 mm wide. Stems often attenuated with leaves becoming progressively smaller towards the shoot tips, rhizoids densely fasciculate, on the stem at the base of the underleaves. Branches ventro-lateral. Leaves succubous, spreading at a wide angle from the stem, slightly convex, alternate, not dorsally decurrent; leaves usually 1.4–2.0 mm long, 0.9–1.5 mm wide, ovaloblong, transversally to obliquely truncate, margins entire and smooth, apices usually lunate with a single acute tooth at both distal angles, to shallowly bifid, lobes short, widely triangular, minutely apiculate, some leaves with rounded apices. 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 semicircular, lateral margins with a small obtuse tooth on both sides, teeth sometimes linear, lobes erect or crescent shaped, narrowly lanceolate acuminate to linear, sinus lunate. Sexual condition dioicous. Gynoecia (unfertilized), terminal on very short intercalary ventro-lateral branches without vegetative leaves or underleaves, bracts oval, 1.2 –1.8 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, 1.5 mm long, lobes narrowly lanceolate, more or less convergent, margins entire, perianth 2–2.5 mm long, cyathiform, smooth, mouth tri-lobate, lobes deeply laciniate. Androecia not seen.

Etymology. – The species epithet refers to its morphological resemblance to Lophocolea pilistipula .

Distribution and ecology. – Chiloscyphus parapilistipulus is only known from three specimens from the Dogny region (Mt Dogny and the Dogny plateau) of New Caledonia at altitudes between 900 to 1050 m where it grows on damp rocks in wet forest.

Notes. – The two specimens collected by L. Le Rat in Mt Dogny are sterile. A fertile plant with similar vegetative characters to the Le Rat material was collected on the Dogny plateau in 2016 by the first author. This facilitated the generic assignment and the description of a new species. It belongs to the genus Chiloscyphus Corda because of the morphology of the gynoecia and vegetative characters such as the free underleaves and the alternate leaves. Chiloscyphus is characterized by terminal gynoecia on short intercalary ventro-lateral branches that lack vegetative leaves or underleaves. Androecia are absent so this plant appears to be dioicous and exhibits a gynoecia implantation that is different from the Lophocolea - type ( HENTSCHEL et al., 2006).

Chiloscyphus parapilistipulus resembles Lophocolea pilistipula but differs in the much larger size of its shoots, leaves and cells, the absence of trigones, the plane outer cell walls so that leaf margins are smooth. The latter has shoots that are 1.5 mm wide, leaves that are 0.8–1.2 mm long and 0.5–0.8 mm wide near the base and leaf cells that are 16–30 µm wide.

The new species differs from all the Lophocoleaceae known from New Caledonia ( THOUVENOT et al., 2011) and from Chiloscyphus species reported from neighbouring countries with bryophyte floras that have floristic relationships with New Caledonia.

Paratypus. – NEW CALEDONIA. Prov. Sud: “In jugo Dogny ”, 1050 m, VII.1909, Le Rat s.n. ( G [ G00051491 , G00051492 ], PC [ PC0102406 , PC0150609 ], REN).

Figures

Fig. 1. – Chiloscyphus parapilistipulus Thouvenot: habit, dorsal view. [Thouvenot NC2451]

Fig. 2. – Chiloscyphus parapilistipulus Thouvenot. A. Shoot portion, ventral view; B. Leaf cells; C, F. Leaves; D–E, I. Underleaves; G–H. Female bracts; J. Female bracteole; K. Perianth open and flattened. [Thouvenot NC2451, PC] [Drawings: L. Thouvenot]