Riccardia innovans (Steph.) Pagán

Reeb, Catherine, Bernard, Elisabeth Lavocat & Gradstein, S. Robbert, 2022, An integrative taxonomic revision of Aneuraceae H. Klinggr. (Marchantiophyta) from Guadeloupe and Martinique, French West Indies, Cryptogamie, Bryologie 20 (8), pp. 135-152 : 143

Riccardia innovans (Steph.) Pagán

( Fig. 3 )

Aneura innovans Steph. , in Urban, Symbolae Antillarum 2: 470 (1901). — Riccardia innovans (Steph.) Pagán , The Bryologist 45: 80 (1942). — Type: Guadeloupe. Savane-à-Mulets, “sur les arbrisseaux”, 1901, with R. chamaedryfolia, A. Duss 484, ex hb. Urban (lecto-, designated byGradstein & Lavocat-Bernard [2020], G[G00066662]!, c.gyn.; isolecto-, NY[00611716]!).

ADDITIONAL SPECIMEN EXAMINED. — Guadeloupe. Carbet Falls, 16°02’45”N, 61°38’40”W, 910 m, 28.VII.2013, on humid, sloping soil, Lavocat Bernard & Reeb 1901.

DISTRIBUTION AND HABITAT. — Only known from Guadeloupe, growing on bark or soil.

FURTHER ILLUSTRATION. — Gradstein & Lavocat Bernard (2020).

REMARKS

Riccardia innovans is a very rare endemic species of Guadeloupe that is characterized by the delicate, 2-pinnate plants with a very narrow, only 0.15-0.25 mm wide, biconvex,

almost wingless axis and numerous long and narrow, linear to subulate branches. The branches are only a little narrower than the axis, plano-convex, obliquely to widely spreading, usually tapering to narrow tips, and narrowly winged by 1-2 cell wide wings. The presence of small scales on the calyptra, made up of large cells, may be a further characteristic of the species. The plants are dioicous; gemmae have not been observed Riccardia innovans approaches R. regnellii , but the latter is a larger plant with a flat axis (not biconvex) and with broader, frequently tongue-shaped branches. In the type material, some R. regnellii plants are growing mixed in the dense mat of R. innovans and are immediately recognized by their much larger size ( Gradstein & Lavocat Bernard 2020).

The isolectotype of R. innovans (NY) has long, thin and vegetative innovations looking as ultimate branches, all along the female branch ( Fig. 3F ); this could be also a retained character for the species. Riccardia innovans is hitherto only known from the type specimen and a single recent collection made by the first two authors in 2013. Unfortunately, the latter material could not be amplified molecularly.

Figures

FIG. 3. — Riccardia innovans (Steph.) Pagán: A, isolated thalli (bleach + methylen blue coloration); B, branching patterns; C, ultimate branch; D, main axis cross section;E, ultimate branches cross section; F, vegetative innovations along female branch.All from the lectotype A. Duss 484. Scale bars:A, 1 mm; B, F, 500 µm; C, 250 µm; D, E, 100 µm.