Riccardia vohimanensis Reeb & Gradstein 2020, sp. nov.
Creators: name: Reeb, Catherine
name: Gradstein, Robbert
Publisher: name: Zenodo
Year: 2020
Subjects: Biodiversity
Taxonomy
Plantae
Marchantiophyta
Jungermanniopsida
Metzgeriales
Aneuraceae
Riccardia
Riccardia vohimanensis

description: Riccardia vohimanensis Reeb & Gradst. sp. nov.   (Fig. 4 U-X)  
DIAGNOSIS. — Monoicous. Thallus rigid, unwinged, with short branches. Axis plano-convex to biconvex, 8-12 cells thick, ventral side with mycorrhiza-like fungi. Immature calyptra strawberry-like.  
 TYPE. — Madagascar. Vohimana Reserve, 18°55’43.6S 48°29’53.6”E 849 m, 15.IV.2010, Reeb, Andriamantena & Bidault CRAE 96 * (holo-, PC [PC 0771053]).   
 FURTHER SPECIMENS EXAMINED. — Madagascar. Alaotra-Mangoro, Zahamena Reserve, 17°38’22”S, 48°38’47”E, 1247 m, 27.XII.2013, Reeb CR 13 Z 23* (PC 0763868); Maromizaha Reserve, 18°58’33.9”S 48°27’54.3”E, 1021 m, 05.VII.2012, Reeb MTM1278* (PC 0763879), 18°58’45”S, 48°27’51.8”E, 1011 m, 06.VII.2012, Reeb MTM1290* (PC 0763878); Haute Matsiatra, Andringitra Nat. Park, 22°08’4061” S, 46°53’47.4”E, 1590 m, 21. V.2016, Reeb CR 16 M 52 (PC).   
 Malawi. Mulanje Mt., 15°53’32.1”S, 35°29’24”E, 2180 m, 22. VI.1991, O’Shea M 7327A-2* (E 00430480).   
 Mauritius. Macabé, 550 m, 03.X.1962, Een M 028* (S-B7097).   
DISTRIBUTION. — Malawi, Madagascar, Mauritius.  
HABITAT. — On dead logs (bare, smooth and very hard wood) and buttresses, rarely on humid rock, from 550 m to 2200 m.  DESCRIPTION  
Monoicous (autoicous or paroicous).   Thallus   
Leathery and rigid, green to blackish green when fresh and forming rosettes on bare substrates, dull brown to black in herbarium, closely attached to the substrate, to 22 mm long, 1-2-pinnate, not palmate, branches alternate, not flagelliform, stolons lacking.   Main axis   
Well-defined, 700-1000(-1200) µm wide, in cross section plano-convex to concave-convex, with mycorrhizal fungi in the ventral part, 8-12 cells thick, margins obtuse, not winged, epidermis cells 2-4× smaller than inner cells.   Ultimate branches   
Oblong and stocky, to 2 mm long and 1 mm wide, in cross section biconvex to plano-convex, 7-9 cells thick, margins acute, not winged, branch apex rounded and often widened, emarginate to weakly dissected, without overlapping edges.   Mucilage papillae   
Apical and lateral.   Oil bodies   
Not seen.   Sexual branches   
Numerous all along axis, often close to each other.   Male branches   
Mainly grouped, sessile, 300-400 µm long, not winged, with 4-8 antheridial pairs.   Female branches   
Grouped, laterally inserted, 300-500 µm long, base often elongate, female branch bordered by scales or long hair-like, straight cilia, the cilia longer than the width of the axis, archegonia in 4-6 pairs.   Calyptra   
Less than 1 mm long, strawberry-like when immature, densely covered by rounded, thick-walled cells.   Gemmae   
Sometimes present.
description: Published as part of Reeb, Catherine & Gradstein, Robbert, 2020, A taxonomic revision of Aneuraceae (Marchantiophyta) from eastern Africa with an interactive identification key, pp. 11-34 in Cryptogamie, Bryologie 20 (2) on page 31, DOI: 10.5252/cryptogamie-bryologie2020v41a2, http://zenodo.org/record/12215441