Plants very small, budlike, dull dark-green to brownish green, in scattered, gregarious or sometimes very small clumps. Thallose protonematal flaps persistent and usually present. Stems few, very short, less than 0.05 cm; flagelliform shoots may occur at the base of the stem, 0.2–0.5 cm, with 3-ranked, tightly appressed linear to lanceolate leaves. Leaves of main stem few, appressed, ovate, acuminate, or obtuse, margins entire or dentate, to 1.2 mm; costa single, weak or absent; laminal cells rhombic or rectangular. Specialized asexual structures absent. Sexual condition: perichaetial and perigonial buds occurring on the same protonema; perichaetial leaves ovate to ovate-lanceolate, concave. Seta 3–8 mm, straight, smooth, slightly twisted when dry. Capsule 0.6–1 mm, ovate to shortly oblong-cylindric, straight; operculum conic, obliquely apiculate; peristome usually not splitting or appearing to be more than four. Calyptra smooth or somewhat plicate, yellowish. Spores smooth or finely papillose, 10–16 µm.

Distribution

North America, South America (Chile), Eurasia, Pacific Islands (New Zealand).

Discussion

Species 2 (2 in the flora).

Selected References

None.

Lower Taxa

Tetrodontium brownianum, Tetrodontium repandum

Key

1	Plants with numerous flagelliform shoots, protonematal flaps less than 0.5 mm.	Tetrodontium repandum
1	Plants without flagelliform shoots, protonematal flaps 0.5-2.5 mm.	Tetrodontium brownianum