Mielichhoferia Nees & Hornsch.

Elements in the following description were taken from Crum’s (1994) treatment of Schizymenium for Mexico and from Shaw & Ramsay’s (2013) treatment of Mielichhoferia for Australia.

Plants small, pale green or yellow-green, mostly lustrous, forming turves or loose to compact tufts. Stems erect, unbranched or forked. Leaves reduced on lower stem or uniform throughout, not complanate, erect or erect-spreading when moist, scarcely altered when dry, ovate-lanceolate to narrowly lanceolate, acute or acuminate, usually toothed above, unbordered, not decurrent; mid laminal cells linear-rhomboidal, usually laxer and ± subquadrate at base. Costa failing below leaf apex, percurrent, or rarely short-excurrent.

Dioicous or less often paroicous, autoicous, or synoicous (mostly paroicous in N.Z. material). Perichaetia basal, with leaves smaller than vegetative leaves. Perigonia, when present, lateral and gemmiform. Setae elongate, slender, flexuose; capsules inclined or pendulous, rarely inclined or erect (as in N.Z. species), symmetric or slightly curved, often slightly swollen on one side, pyriform to oblong-cylindric, with a short or ± elongate, smooth or wrinkled neck; mouth transverse, not narrowed; annulus persistent; operculum conic, sometimes ± apiculate. Peristome double, single and endostomal, or rarely absent; exostome, if present, smooth and blunt; endostome usually consisting of ± linear, smooth or papillose segments (sometimes blunt, irregular, or anastomosing) arising from a low basal membrane and lacking cilia. Spores spherical, smooth, or ornamented.

A type species for Mielichhoferia Nees & Hornsch. has not been designated. The type species for Schizymenium Harv. is Schizymenium bryoides Harv.

Dixon (1926) accepted three species of Mielichhoferia in our flora. Sainsbury (1955) recognised two species here, retaining them both in Mielichhoferia. Scott & Stone (1976) recognised only one species of Mielichhoferia from south-eastern Australia. The generic placement of the southern hemisphere and Australasian species placed by these authors in Mielichhoferia has become less clear in recent years. Following on from a study by Shaw & Crum (1984) of the peristome in Mielichhoferia s.l., Shaw (1985) advocated the resurrection of the segregate genus Schizymenium Harv. for species with mostly paroicous sexuality and peristomes either entirely endostomal in nature or double and with unornamented exostome teeth.

Shaw (1985) provided a key to the three genera (Mielichhoferia, Schizymenium, and Synthetodontium Cardot) in what, at that time, he termed the subfamily Mielichhoferioideae of the Bryaceae. He simultaneously made new combinations in Schizymenium for 39 species, most of them previously placed in Mielichhoferia. A new combination was not made for the southern hemisphere Schizymenium bryoides Harv. as this species was originally described in Schizymenium.

Shaw & Ramsay (2013) more recently published a revision of the Australian material of Mielichhoferia, placing it together with Pohlia and Epipterygium, in a segregate family, Mielichhoferiaceae.

Shaw studied Mielichhoferia, Pohlia, and their allies for many years, and not surprisingly his concepts of its family placement and the circumscription of these genera have evolved.

Shaw & Ramsay (2013) opined that “molecular studies have shown that Mielichhoferia includes a natural (i.e., monophyletic) group of species that can have exostomial, endostomial or double peristomes. The sole Australian species of Schizymenium, S. bryoides, [has a peristome that] can be single or double with the exostome reduced or absent”. Consequently they treated the Australian species (which is shared with N.Z.) in Mielichhoferia rather than in Schizymenium. This generic and familial placement is accepted here.

Their commentary on the differences between Mielichhoferia and Pohlia is useful and it is quoted here: “Species of Mielichhoferia often resemble a small Pohlia, and they grow in similar habitats. However, they can be distinguished by the gametangia being borne on short lateral shoots in Mielichhoferia but terminally in Pohlia. Moreover, perichaetial leaves are smaller with a shorter costa and laxer cells in Mielichhoferia but longer or equal to vegetative leaves in Pohlia. The peristome of Mielichhoferia is more variable, usually single, slender, and delicate, reduced to 16 endostome segments joined at the base by a low basal membrane. By contrast, it is usually double, well developed and less variable in Pohlia”.

Mielichhoferia includes about 90 species and is most diverse in South America. Shaw & Ramsay’s (2013) statement that only a few of the species “could be regarded as being well known” suggests that revisionary work may result in a reduced number of species.