1. Mielichhoferia Nees & Hornschuch in C. G. D. Nees et al., Bryol. Germ. 2(2): 179, plate 41. 1831. • [For Mathias Mielichhofer, 1772-1847, Austrian collector of generitype specimen].
Plants small to medium-sized, occasionally large, usually in ± compact turfs. Stems 0.1-3 cm, bearing lateral gametangia when fertile. Leaves erect to ± spreading, narrowly lanceolate to ovate-lanceolate, 0.5-1.3 mm; base not decurrent; margins plane [rarely recurved], finely serrate to serrulate near apex, rarely entire; apex acute or short-acuminate; costa ending well before apex to subpercurrent; distal medial laminal cells hexagonal to rhomboidal; marginal cells undifferentiated. Specialized asexual reproduction absent or rare, by axillary bulbiform gemmae. Sexual condition dioicous or synoicous; perigonia and perichaetia on short lateral branches; perigonial leaf apex short-acute; perichaetial leaves usually smaller than vegetative leaves, lanceolate to narrowly linear-lanceolate. Seta single, color various, straight or bent. Capsule erect or inclined to 30°, narrowly cylindric to pyriform, 1-4 mm, neck shorter than urn; exothecial cells near mouth in 1-3 rows, medial cell walls straight or slightly sinuate; stomata superficial; annulus revoluble; operculum convex, short- to long-conic; peristome single or double, appearing single, usually 4:2:4; exostome, when present, white to hyaline, teeth narrowly acute- or blunt-triangular, sometimes irregular, often reduced or absent, weakly or not trabeculate, papillose; endostome basal membrane rudimentary or scarcely exceeding capsule rim, segments sometimes absent, or narrow, slightly keeled, not perforate, cilia absent.
Species ca. 45 (3 in the flora): North America, Mexico, South America, Europe, Africa, Pacific Islands (New Zealand), Australia.
Mielichhoferia is characterized by perichaetia and perigonia borne on short lateral branches, perichaetial leaves that are often smaller than the vegetative leaves with cells relatively more lax, and frequent peristome reduction. The leafy stems themselves are much like those of a small Pohlia.
Mielichhoferia is especially diverse in South America and is highly variabLeón peristome development: double with well-developed exostome and endostome, singLeónd endostomial, double but with the exostome short and barely exceeding the capsule rim, or double with the endostome reduced to an inconspicuous membrane adherent to the exostome teeth (two North American species). Species of Mielichhoferia are gametophytically similar to small species of Pohlia, though they can be distinguished by a characteristic whitish color and very small size. The main features distinguishing the two genera are gametangia borne on short lateral shoots in Mielichhoferia and terminal in Pohlia. The perichaetial leaves are as long as or longer than vegetative leaves in Pohlia but are smaller, with more lax cells and shorter costa in Mielichhoferia. Mielichhoferia and Pohlia grow in similar habitats.
SELECTED REFERENCES Shaw, A. J. 1994. Systematics of Mielichhoferia (Bryaceae: Musci) II. Morphological variation among disjunct populations of M. elongata and M. mielichhoferiana. Bryologist 97: 47-55. Shaw, A. J. and H. A. Crum. 1984. Peristome homology in Mielichhoferia with a taxonomic account of the North American species. J. Hattori Bot. Lab. 57: 363-381. Shaw, A.J. and P. E. Rooks. 1994. Systematics of Mielichhoferia Nees & Hornsch. (Bryaceae: Musci) I. Morphological and genetic analyses of M. elongata and M. mielichhoferiana. Bryologist 97: 1-12.