Riccia hasskarliana Steph.

Thouvenot, Louis & Müller, Frank, 2021, Contribution to the bryophyte flora of New Caledonia IV. Species new to the country, new localities together with taxonomic notes, Cryptogamie, Bryologie 20 (13), pp. 181-196 : 187

* Riccia hasskarliana Steph.

SPECIMEN EXAMINED. — New Caledonia. South Province, Sarraméa, along the hiking trail from Sarraméa to the Plateau de Dogny, 21°38’S, 165°52’E, on wet open soil along the trail, together with Physcomitrium minutulum Müll.Hal. , c. 200 m, 05.IX.2003, Müller NC872 (DR).

COMMENTS

The genus Riccia L.is represented in New Caledonia by R. crinita Taylor and R. numeensis Steph. , doubtful records exist for R. fluitans L. and R. junghuhniana Nees & Lindenb. ( Thouvenot et al. 2011). Riccia crinita and R. numeensis both are belonging to sect. Riccia ; the latter one is endemic to New Caledonia and was described by Stephani based on sterile material.

The specimen Müller NC872 belongs to subgenus Ricciella . The thallus cross-section shows regularly large air chambers ( Fig. 3D, E ). The capsules are bulging into spherical structures on the ventral surface. The inner thallus cells are thick-walled. The spores are about 60 µm in diameter and clearly reticulate on both faces with 7-8 alveolae across diameter on distal face and a small wing ( Fig. 3 A-C).

Riccia hasskarliana is very similar to R. junghuhniana and R. multifida (Steph.) Steph. Riccia junghuhniana is a larger plant with branches 1.25-2.5 mm wide, with narrow airchambers ( Meijer 1958) and the sporophytes are not as prominent on ventral surface. Riccia hasskarliana differs from the Australian R. multifida by spores with a less prominent wing and a lower number of alveolae across diameter on the distal face of the spores (6-8 vs 8-12) ( Cargill et al. 2016).

Riccia hasskarliana was hitherto known from Indonesia (Java,

Kalimantan, Sumatra) ( Meijer 1958) and India ( Singh 2014).

Figures

FIG. 3. — Riccia hasskarliana Steph.: A, spores; B, spore in distal view; C, spore in proximal view; D, thallus cross section; E, detail of thallus cross section showing the thick-walled interior cells. All from F. Müller NC872. Scale bars: A, E, 50 µm; B, C, 10 µm; D, 100 µm.