Riccardia vohimanensis Reeb & Gradst., 2020

Reeb, Catherine & Gradstein, Robbert, 2020, A taxonomic revision of Aneuraceae (Marchantiophyta) from eastern Africa with an interactive identification key, Cryptogamie, Bryologie 20 (2), pp. 11-34 : 31

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.

Figures

FIG. 4. — Riccardia martinii sp. nov.: A, thallus mats; B, dry thallus, showing white margins; C, moistened thallus; D, portion of thallus in dorsal view, showing thickened cell walls; E, apex of ultimate branch, showing papillae; F, main axis in cross section; G, ultimate branches in cross section; H, calyptra; I, portion of thallus with male branches. From Sass-Gyarmati 9613/CW, Vojko 9660/CS, Pócs 9602CU, 6877/K, Bardat JBMAD78 (PC0763890), Riccardia ramosissima (Steph) Grolle: J, thalli; K, main axis in cross section; L, ultimate branches in cross section; M, male branch; N, calyptra; O, upper portion of calyptra, showing umbo. From Reeb CR13Z51 (PC0763864), Pócs 6981/A, Jelinek s.n. (Type of Aneura compacta). Riccardia saccatiflora (Steph.) S.W.Arnell: P, thalli; Q, main axis in cross section; R, ultimate branches in cross section; S, portion of thallus with two female branch (left) and two male branches; T, calyptra. From Wigginton M1758b, Reeb CR11142 (PC0763883), Een M064, Rodriguez 182 (Type of Aneura saccatiflora). Riccardia vohimanensis Reeb & Gradst.: U, thalli; V, main axis in cross section; W, ultimate branch in cross section; X, sporophyte and calyptra with the vegetative expansion at its basis. From Reeb MTM1278 (PC0763879), CR13Z23 (PC0763868), O’Shea M7327b, Een M028. Scale bars: A-C, H-J, N, P, U, 1 mm; D-G, M, Q, T, V-X, 500 µm; K, L, R, 100 µm; O, S, 200 µm.