Riccardia sp.
Diagnostic characters—Thalli, irregularly pinnately branched yellowish-green; 3-5 cells thick in cross section; thallus margins strongly crenulate, unistratose, winged, 3-4 cells wide; epidermal cells smaller than inner cells, quadrate to hexagonal, thin-walled, smooth; oil bodies finely and with some coarsely large segments, globose to ellipsoid and vermiculate, brownish, 1 per cell in epidermal layers, 1-3 per cell in inner layers; Autoicous. Male inflorescences on both sides of thallus margins; female inflorescences on both sides of thallus margins with obovate-lanceolate involucres, entire in lower part, scabrid in upper part, up to 2 mm long; capsule blackish, cylindrical; seta pellucid, erect; elaterophores on the ultimate capsule walled, 4 dehiscent valves; elaters unispiral, brownish; spores spherical, brownish, smooth.
Ecology—on rocks in stream in mixed evergreen+deciduous, seasonal, hardwood forest, granite bedrock, Sirindhorn Observatory area, c. 870 m elevation, Huay Pa Laht (stream), c. 750 m elevation, Montahtahn Falls, c. 684 m elevation.