Ptychomniaceae M.Fleisch.

Elements in the following description are translated from Brotherus (1925).

Plants robust or slender, lustrous, forming loose or tight wefts, epiphytic or terrestrial. Primary and secondary stems mostly distinct (except in Ptychomnion). Primary stems creeping, short or long, often either lacking or difficult to observe, rigid and sometimes brittle, mostly leafless. Secondary stems usually clustered, ascendant or pendent and curved away from the substrate, often rigid, simple or sparsely branched, mostly lacking rhizoids except for fascicles at the base, in cross-section oval or angular, lacking a central strand, with several layers of thick-walled and often strongly pigmented cortical cells. Leaves of secondary stems mostly dense or imbricate, usually in several rows, rarely complanate, lanceolate to broadly oval, mostly symmetric, sometimes decurrent, often plicate, unbordered, mostly toothed above, often recurved or twisted at apex; mid laminal cells linear, elliptic, or ± rhombic, thick- or rarely thin-walled (in Hampeella), mostly strongly porose, smooth; cells at insertion mostly strongly porose and pigmented, often forming a distinct band across the leaf base; alar cells variable. Costae absent or short and either double or single. Paraphyllia absent or present. Gemmae often present on upper stems; if present filamentous, acicular, or clavate; cells uniseriate with transverse walls.

Dioicous, often with dwarf and epiphyllic male plants. Perichaetia on short branches; the inner leaves shouldered and subulate and often (always?) enlarging after fertilisation. Perigonia small and bud-like. Setae elongate and straight or ± flexuose, smooth; capsules erect or curved and ± horizontal, ovoid to cylindric, strongly 8-ribbed; exothecial cells firm- or thick-walled; stomata few and restricted to extreme base of capsule, superficial; annulus absent or present; operculum rostrate from a conic base, sometimes longer than the capsule. Peristome double or rarely single; exostome teeth inserted close to rim, lanceolate, yellow or pale, often furrowed, rarely absent (in Dichelodontium); endostome arising from a low or high membrane, the segments well developed or rudimentary; cilia usually absent (present in Ptychomnion). Calyptra cucullate, smooth, and elongate. Spores one-celled or multicellular (in Cladomnion).

As traditionally circumscribed, the Ptychomniaceae are a small family of seven genera and about 15 species (Brotherus 1925) restricted to the southern hemisphere. Brotherus isolated Ptychomnion into a subfamily of its own on the basis of its having curved and strongly ribbed capsules. By Brotherus’s concepts, the family has maximum generic diversity in N.Z., with six of seven genera found here, although the recent description of two monotypic genera restricted to South America alters this view. The strongly ribbed capsules, the often plicate leaves, and the long rostrate opercula are features that help to characterise the family.

Most species occur mainly on tree trunks and branches, although Ptychomnion is primarily terrestrial in N.Z. The majority of the epiphytic taxa grow on a wide range of host tree species; the host species are not listed for the members of this family.

Temperate South America has a comparable diversity at the genus level, but a greater number of species than N.Z. Buck et al. (2005) raised the section Ptychomniella Broth. to generic rank; it is monotypic and restricted to southern South America. Bell et al. (2007) recently described a new genus, Ombronesus, with a highly reduced endostome, from the Aysén region of southern Chile. A proposal to shift Dichelodontium to the Lepyrodontaceae by Allen (1999), based partly on peristome studies by Magill (1987), is not accepted here. Phylogenetic studies by Bell et al. (2007) show Dichelodontium to be nested in a clade with other members of the Ptychomniaceae, and the transfer was not followed by Goffinet et al. (2009).

Recent studies (Buck et al. 2005; Bell et al. 2007), using both molecular and morphological characters, have greatly enlarged this traditional (Brotherean) view of the family. Apart from newly described genera, mentioned above, the most notable change is the proposed transfer of the large, predominantly southern Asian and Malesian genus Garovaglia, and the allied genus Euptychium, to the Ptychomniaceae from the Pterobryaceae. According to During (1977, p. 9), Garovaglia and its allies comprise a "rather distinct, natural group", the Garovaglioideae, in the Pterobryaceae. Garovaglia and its allies differ from N.Z. members of the Ptychomniaceae in many sporophytic features, with short, non-ribbed capsules borne on short setae. They also lack the distinctively long rostrate operculum found in other members of the Ptychomniaceae. These morphological differences mean that the transfer of Garovaglia and its allies to the Ptychomniaceae makes the family less cohesive and far more difficult to characterise morphologically.

For the purposes of this Flora, this proposed expansion of the Ptychomniaceae is of little practical significance, as all our taxa are included in the expanded family concept presented by Goffinet et al. (2009). They placed the Ptychomniaceae in its own order, the Ptychomniales, in the general relationship of the Hypnodendrales and the Hookeriales. The furrowed and shouldered exostome teeth of some of the genera occurring in N.Z. make an alliance with the Hookeriales and Hookeriaceae plausible.

Ptychomnion is the largest genus in the family and contains five to eight species, depending on interpretation. Three of the six genera present in N.Z. (Cladomnion, Dichelodontium, and Tetraphidopsis) are monotypic endemics. Cladomniopsis, Ombronesus, and Ptychomniella are each monotypic and restricted to southern South America. A phylogenetic study by Bell et al. (2007) showed Ptychomniella to be sister to a clade including all the N.Z. genera, plus Garovaglia, and Euptychium, but excluding Hampeella.

The family as circumscribed here is the most species-rich in N.Z., Patagonia, and Juan Fernandez I., and also occurs on N.Z.’s southern offshore islands (including Macquarie I.), in Tasmania, south-eastern mainland Australia, southern Brazil, Marion and Crozet Is, New Caledonia, Malesia, Polynesia, and probably Sri Lanka and the Philippines.