Wettsteinia Schiffn.
Wettsteinia Schiffn., Ann. Jard. Bot. Buitenzorg 2 (Suppl.): 44. 1898.
Type: Wettsteinia inversa (Sande Lac.) Schiffn. (≡Plagiochila inversa Sande Lac.)
Plants usually pure green, lacking secondary pigments, the lower parts of stems white, the leafy shoots erect, arising from a system of plagiotropic, copiously branched, colorless, rhizoidous axes, the leafy shoots medium to vigorous, to 7 cm tall, the leafy shoots typically becoming smaller-leaved distally. Branching ventral-intercalary, arising from the stolons and lower sectors of leafy shoots; terminal branching absent. Stems with hyaloderm comprised of thin-walled cells that soon collapse and erode, the stem becoming roughened, the hyaloderm surrounding 3–5 strata of smaller, thick-walled, subepidermal cells that gradually grade into the hyaline, large-celled medulla. Rhizoids absent on leafy shoots. Leaves optimally developed only in median shoot sectors, smaller distally and below median sector, those of median sector 2–4-stratose toward base, remote to weakly imbricate, weakly to distinctly concave, ovate to obovate or orbicular-cordate, copiously dentate, the teeth larger and more remote on dorsal margin (lacking in Wettsteinia densiretis), smaller on apex and ventral margin. Cells in median sector of leaf with walls firm and at most moderately thickened or thin and with trigones at most weakly bulging, the basal cells only moderately elongated (to 60 µm), a vitta absent; marginal cells usually firmer-walled. Oil-bodies hyaline, 10–18 per cell in median sector of leaf, finely papillose. Underleaves vestigial, at times discernible on lower sectors of leafy shoots, ciliiform on upper shoot sectors. Asexual reproduction absent.
Plants dioecious. Androecia on strongly abbreviated intercalary branches from plagiotropic stolons, minute; bracts in 2–4 pairs, bleached, tiny, dense, inflated; antheridia 1(rarely 2) per bract, the stalk uniseriate. Gynoecia on strongly abbreviated intercalary branches from basal sectors of erect shoots or from plagiotropic stolons; bracts and bracteoles small, bleached, irregularly laciniate, comprised of thin-walled hyaline cells. Perianth absent. Shoot-calyptra rigid, fleshy, stoutly clavate, green, long-exserted beyond bracts, the sterile archegonia and at times a few bractlets elevated on the shoot-calyptra.
Foot conical, with a distinct haustorial collar. Seta massive. Capsule moderately long-ellipsoidal, the wall 6–8-stratose, the outer layer of cells mostly devoid of thickenings but some cells with nodular to spur-like thickenings on radial walls, the cells that possess thickenings sporadic and without a regular pattern of distribution; innermost layer of cells with semiannular bands.
Spores with close papillae and very short-vermiculate markings. Elaters bispiral.
A genus of four species, two in Austral areas. Wettsteinia densiretis (Herzog) Grolle oc- curs in the Falkland Islands, southern South America (Valdivian) and Juan Fernandez, and W. schusteriana Grolle is found in our area. Wettsteinia inversa (Sande Lac.) Schiffn. occurs in New Guinea, Indonesia, Borneo, the Philippines and Taiwan, and W. rotundifolia (Horik.) Grolle is found in Taiwan.
References: Grolle (1965b); Schuster (2002a).
