Riccardia corbieri (Steph.) 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 : 20-21

Riccardia corbieri (Steph.) Reeb & Gradst. comb. nov. Fig. 2 J-N

Aneura corbieri Steph. , Species Hepaticarum 6: 23, 1917. — Type:

Madagascar, 1898, Leloutre 126a (G[G00045028]!).

Aneura nudiflora Steph. , Hedwigia 31: 199 (1892). — Riccardia nudiflora (Steph.) Grolle, Bryophytorum Bibliotheca 48: 130 (1995). — Type: Mauritius, Robillard s.n. (lecto- fide Reeb & Bardat [2014], G[G0037569]!) syn. nov.

FURTHER SPECIMENS EXAMINED. — Madagascar. Sava, Makirovana, 14°10’17.4”S, 49°57’07.5”E, 508 m, 07.V.2010, Reeb & Pierrot CR295* (PC0763837A, TAN), CR297* (PC0763838A, TAN).

Seychelles. Mahé, Pointe au sel, 139 m, 20.IX.2012, Senterre & Labiche-Barreau 6310* ( PC 0763853, SEY), Mare aux cochons, 562 m, Senterre & Labiche-Barreau 6258* ( PC 0763852, SEY), 18.II.2012, Beaver B 304* ( PC 0763848, SEY).

DISTRIBUTION. — Madagascar, Mauritius, Seychelles.

HABITAT. — On rock or dead wood in humid evergreen forests, from 100 to 560 m.

DESCRIPTION

Monoicous (autoicous).

Thallus

Green to olive green when fresh, yellow green to bright brown in herbarium, fleshy but not leathery, usually dull (rarely glossy), mostly flat, to 20 mm long, main axis creeping and attached to the substrate, branches ascending to erect, mostly 1-2-pinnate, not palmate, branches alternate to subopposite, flagelliform branches absent, stolons often present on the main axis, especially near the base in young plants, ultimate ascending branches wider than creeping ones.

Main axis

Very irregularly defined, in cross section ellipsoid to biconvex, 5-6(-9) cells thick, margins rounded, not winged (exceptionally margin cells bulging outwards), epidermis cells 2-4× smaller than inner cells, all cell walls thickened in mature thalli.

Primary branches

Erect, to 15 mm long, rarely overlapping.

Ultimate branches

Tongue-shaped to triangular, often sinuose, 3-5 mm long, 0.8- 1.2 mm wide, cells usually in straight rows, rarely in diverging rows, in cross section plano-convex to concave-convex, with 4-5 cells wide wings, the wings narrower to as wide as the midrib, epidermis cells 2-3× smaller than inner cells, branch apex rounded to truncate to emarginate.

Mucilage papillae

In two ventral rows, persistent.

Oil bodies

Not seen.

Male branches

Along main axis and primary branches, solitary, sessile, with a narrow, one cell wide wing.

Female branches

Straight, laterally to ventro-laterally inserted, margins with up to eight cells long cilia and with broad wings as wide as or wider than the axis, the wings sometimes recurved and branch becoming cup-shaped.

Calyptra

Smooth, with a triangular umbo of aggregate cells.

Gemmae

Occasionally present, 2-celled.

Figures

FIG. 2. — Riccardia angusticosta (Steph.) Grolle: A, thalli; B, main axis in cross section; C, ultimate branch in cross section; D, calyptra; E, upper portion of calyptra, showing umbo. From Thollon s.n. (Aneura stephanii TYPE), Pócs 9883/H, Brenan140. Riccardia chamedryfolia (With.) Grolle: F, thalli; G, portion of thallus showing male and female branches;H, main axis in cross section;C, ultimate branch in cross section.From Reeb CR11156 (PC0763897), CR11418 (PC0763898), Hylander KH5497 (PC0763862). Riccardia corbieri (Steph.) Reeb & Gradst. comb. nov.: J, thalli; K, main axis in cross section; L, ultimate branch in cross section; M, portion of thallus with female branch;N, ultimate branches and calyptra.From Beaver B304 (PC0763848), Reeb CR297 (PC0763838A),CR295 (PC0763837A). Riccardia fastigiata (Lehm.) Trevis.: O, thalli; P, main axis in cross section; Q, ultimate branches in cross section; R, portion of thallus with femalre branches and calyptra. From Vojko 9422/AP, Pócs 6929/T, Orban 9615/CB (PC0146833). Scale bars: A, D-F, J, M-O, R, 1 mm; B, C, G-I, K, 500 µm; L, P, Q, 200 µm.