Riccardia chamedryfolia (With.) Grolle

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 : 18-20

Riccardia chamedryfolia (With.) Grolle

( Fig. 2 F-I)

Jungermannia chamedryfolia With., A Botanical Arrangement of the Vegetables of Great Britain 2: 699 (1776). — Type: England ( Grolle 1976).

SPECIMENS EXAMINED. — Comores. Grandes Comores, Karthala, 1600 m, 01.V.2008, Bardat KarP1Q2Hu1* (PC0763845).

Ethiopia. Bonga, Araba Yel forest, 37°80’77.54”N, 18°73’34”E, 1798 m, Hylander KH 5490* ( ETH, PC 0763857); Boka forest, 02.XI.2006, Hylander KH 5497 * ( ETH, PC 0763862); Bale Mts., Harenna forest, 06°42’58.3”N, 39°43’32.1”E, 2380 m, 10.VIII.2011, Reeb, Queinnec & Wégé CR 11418 * ( ETH, PC 0763898), ibid., road to Rira, 06°43’09.4”N, 39°43’11.3”E, 2392 m, 10.VIII.2011, Reeb, Queinnec & Wégé CR 11425 *( ETH, PC 0763893), CR 11428 * ( PC 0763896, ETH).

Madagascar. Analamanga, Station d’Angavokely, 18°55’44.8”S, 47°45’04.8”E, 1507 m, Reeb & Andriamiarisoa CR 11156* ( PC 0763897, TAN). Malawi. Mulanje Mts., 15°53’32.1”S, 35°29’24”E, 2180 m, 22. VI.1991 O’Shea M 7327A-1* ( E 00430482), Longton M 8299 A * ( E 00430472). France. Réunion, Forêt de Belouve, Plateau Citrons, 21°31.5” S, 55°33.5” E, 1500 m, 18. VI.1996, Pócs 9647 A ( EGR), 1150 m, 09.IX.2013, Bardat REU 1365* ( PC 0146834). Uganda. Kabala, Bwindi National Park, 10°40’S, 02°E, 2050 m, 30. I.1996, Wiggington U 5137 C * ( E 00430554), 2070 m, 26. I.1996, Porley U 97 A * ( E 00430540). Zimbabwe. Melsetter District, Kasipiti, 1200 m, 28.XII.1964, Loveridge 1289 ( EGR).

DISTRIBUTION. — Widespread in temperate regions of the Northern Hemisphere, also in tropical America (e.g. Gradstein & Costa 2003; Schäfer-Verwimp et al. 2013; Rabeau et al. 2017). Newly reported from Africa where the species has been found in St. Helena ( Rabeau et al. 2017), Comores, Ethiopia, Madagascar, Malawi, Reunion and Uganda.

HABITAT. — On dead wood and tree trunks in in sheltered environments in humid forests, also on humid rocks in streams and at the entrance of caves, between 900 and 2400 m.

DESCRIPTION

Monoicous (autoicous or paroicous).

Thallus

Green to brownish when fresh, yellow to bright brown in herbarium, flaccid, dull to glossy, to 20(-40) mm long, loosely to closely attached to the substrate with creeping to erect and sometimes recurved branches, mostly 2-3-bipinnate, sometimes palmate, branches alternate to subopposite, occasionally flagelliform, stolons rare.

Main axis

Not well-defined, variable in width, in cross section plano-convex to concave-convex, 5-6(-7) cells thick, margins acute, with narrow, 1-2 cells wide wings, epidermis cells 3-4× smaller than inner cells.

Primary branches

To 3 mm wide, 5-6(-7) cells thick, rarely overlapping, axis narrowed towards basis.

Ultimate branches

Tongue-shaped, oblong and dense, often fan-like arranged, straight and somewhat widened to the apex, to 3.5 mm long and 1.2 mm wide, in cross section concave-convex to plano-convex, winged, wings 1-4 cells wide, narrower than the midrib, apex enlarged, broad.

Mucilage papillae

Apical and in two ventral rows, persistent.

Oil bodies

Present in nearly all cells, grayish to light brown, 1-2 and rounded in epidermis cells, 1-4(-5) and fusiform in inner cells.

Sexual branches

Solitary or sometimes grouped, sessile, occurring along all the axis, laterally inserted.

Male branches

Bordered by convex cells.

Female branches

Straight, not recurved, margin with more than two cells long scales and cilia, somewhat crisped, fimbriate.

Calyptra

With scattered thick-walled cells, umbo lacking.

Gemmae

Occasionally present, 2-celled.

COMMENTS

Riccardia chamedryfolia has not previously been recognized in Africa, probably due to confusion with the polymorphic R. longispica . A well-delimited cluster of R. chamedryfolia was recovered in the molecular analysis with new records from Guadeloupe, St. Helena and the mainland of tropical Africa, indicating a more widespread distribution of the species than was previously known ( Rabeau et al. 2017). The species is mainly characterized by the winged, plano-convex to concave-convex axis and branches, the broad branch apices, the epidermis cells much smaller than inner thallus cells, and monoicy. Sterile plants may be confused with robust phenotypes of R. longispica and R. saccatiflora but R. longispica is normally dioicous whereas R. saccatiflora lacks an axial wing and is usually palmate, and has dark brown oil bodies.

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.