Bryum amblyodon Müll.Hal.

Plants bright- or yellow-green above, tinged with red below, forming compact turves. Stems red, c. 15–23 mm, branching (often repeatedly) by innovation, densely beset with red-brown, papillose rhizoids, in cross-section with firm-walled cortical cells and a very strong central strand. Leaves becoming larger and more crowded in comal tufts, erect when moist, twisted around stems and ± reflexed when dry, oblong-lanceolate, abruptly acuminate and finely awned, mostly 2–4 × 0.8–1 mm and with lamina c. 0.8 total length, concave, red at base, entire (or finely and distantly denticulate above), distinctly bordered and recurved at margins, weakly decurrent; upper laminal cells oblong-hexagonal, thin-walled, weakly porose, c. 48–66(–75) × 15–18 µm and 3–4:1, becoming longer near apex (and ± fusing with border near apex) and longer and more oblong in lower leaf; marginal cells linear and forming a well-defined border extending to apex; basal cells distinctly pigmented but not otherwise differentiated. Costa red below or nearly throughout, long-excurrent and filling the slender awn, which is entire or remotely denticulate. Brood bodies (including tubers) absent.

Synoicous. Perichaetia mostly several on each plant and overtopped by innovation, enclosed by enlarged comal tufts. Setae 35–45 mm, red, cygneous just below the capsule; capsules pendent, broadly clavate, c. 4 mm, with a well-defined neck c. ½ the total length, little altered when dry; operculum conic, not apiculate. Exostome teeth pale yellow-brown, often dark at base, acuminate at apices, with c. 25 or more lamellae; endostome from a high membrane, with fenestrate segments ± equal the teeth, and cilia rudimentary or lacking. Spores (20–)24–30 µm, finely papillose.

Bryum stenotrichum Müll.Hal. is treated as a synonym with reservation.

Other synoicous species that have decurrent leaf bases and pigmented, excurrent costae (e.g., B. pseudotriquetrum and B. algovicum var. rutheanum) could be confused here, especially in the absence of peristome characters. Bryum pseudotriquetrum has shorter excurrencies and stouter costae, thicker-walled upper laminal cells, and smaller spores, as well as well-developed and appendiculate endostomal cilia. It occurs in generally wetter habitats than those favoured by B. amblyodon.

Bryum algovicum var. rutheanum is a taxon with a shorter (c. 1.5–2 mm) and more distinctly pyriform capsule with a less defined neck. The oblique thickenings between exostome teeth lamellae and the adherent nature of the endostome make B. algovicum var. rutheanum quite distinct from the present species. Also, B. algovicum var. rutheanum occurs mostly on sand and silt at stream and lake margins (rather than on calcareous rock) and at lower elevations than B. amblyodon.

The much commoner B. clavatum generally has more stoutly awned leaves, leaves evenly spaced (not comal) on its stems, and capsules often inclined to horizontal rather than pendent. It is usually associated with seepages, while B. amblyodon is more restricted in distribution and occurs in drier sites.

On thin humus over marble, on outcrops, in talus, or boulder fields. The few documented Nelson L.D. collections are from 1220–1470 m elevation, while the single Canterbury collection came from an artificial habitat (crevices in concrete) at c. 750 m.

Microscopic examination of the peristome, and confirmation of synoicous sexuality is essential to the recognition of this species. The specimen recorded by Bartlett (1984) as Bryum inclinatum (Brid.) Blandow from Winter Peak (a subsidiary peak of Mt Arthur, Nelson L.D.) has not been available for study, but the identification is reasonable, given the known range and habitat of this species.

The type specimen of B. amblyodon has not been available for study. The name B. imbricatum (Schwägr.) Bruch & Schimp. was given to this species in Britain (Smith 2004). The application of the name B. amblyodon Müll.Hal. to N.Z. material of "B. inclinatum" was first suggested by H. Ochi (pers. comm., July 1983). Anderson et al. (1990) cited B. amblyodon Müll.Hal. as the preferred name for "B. inclinatum" in their revised North American checklist.

The relationship of N.Z. B. amblyodon to B. archangelicum Bruch & Schimp. is not clear and is beyond the scope of this Flora. The latter species, and its highly confused synonymy and southern hemisphere distribution, is discussed by Ochyra et al. (2008, p. 484).