Dicranella (Müll.Hal.) Schimp.

Plants mostly small, turf forming. Stems erect, unbranched or branching by innovation, in cross-section with a central strand, mostly sparsely beset with smooth, brown rhizoids. Leaves mostly reduced on lower stem and larger above, mostly wide-spreading, lanceolate or subulate, gradually tapered or abruptly tapered from a well-differentiated, oblong base (especially on upper stem), sheathing or not, entire or variably toothed near apex; laminal cells mostly oblong-rectangular, firm-walled, smooth or occasionally mammillose; alar cells not differentiated. Costa with stereid groups present, or rarely absent. Tubers present or absent.

Dioicous. Perichaetia terminal but often overtopped by innovations. Perigonia terminal, with numerous filiform, yellow paraphyses and bracts, larger and more concave than adjacent vegetative leaves. Setae elongate, flexuose or straight, red-brown or yellow; capsules erect or inclined, symmetric or asymmetric, short-cylindric, ovate, ± obovoid (rarely ± globose in non-N.Z. species), furrowed or smooth, often contracted below the mouth when dry; exothecial cells variable in shape, firm-walled, arranged in distinct columns or not; stomata absent or sometimes present and superficial; annulus absent or present and well differentiated; operculum rostrate and curved. Peristome teeth 16, red-brown below and usually hyaline above, mostly divided c. ½ or occasionally nearly to base, the forks free or occasionally ± anastomosing, the outer surface of the lower part of tooth bearing fine (often difficult to see) or rarely coarse trabeculae traversing the full width of the tooth, the inner surface with a zig-zag line that divides the tooth vertically into asymmetric segments, the entire tooth in surface view appearing vertically papillose-striolate below or papillose throughout, or rarely diagonally striate. Calyptra cucullate. Spores spherical, mostly 15–35 µm.

A large genus, probably of c. 100 species. Occurring in all parts of the world but in tropical areas mainly restricted to high elevations. Nearly all the species occur on mineral soils. The majority of N.Z. species are either austral or Australasian in distribution, and treatments of northern hemisphere species are therefore of limited utility here. Two species shared with South Georgia were treated by Newton (1977). Six species are treated here, while a seventh is known from one record as a glasshouse weed.

Dicranella is treated here in a broad sense so as to include Anisothecium. Anisothecium is sometimes recognised as a distinct genus, mostly on the basis of the presence of a differentiated but non-revoluble annulus, the presence of a basal peristomal membrane, and stomata present at the capsule base.

Material that is not referable to any of the Dicranella species discussed below has been collected from a glasshouse in Christchurch (M.F. Sinclair s.n., CHR 532377). This material is characterised by short, inclined, strumose capsules and entire linear-lanceolate leaves with ± excurrent costae. It appears to be the northern hemisphere D. cerviculata (Hedw.) Schimp.

Species of Dicranella with markedly shouldered and sheathing leaves are easily confused with species of Ditrichum, particularly such species as Ditrichum punctulatum or D. strictum. However, both these species have leaf subulae twisted around their own axis when dry and shorter cells at the leaf shoulder. In general, the narrowing (where it occurs) from the leaf base to the subula is more abrupt in Dicranella than in species of Ditrichum. Peristome differences also serve to distinguish all species of Ditrichum from those of Dicranella.

Because of the likelihood of confusion, the genus Campylopodium is included in the following key.

Dicranella egmontensis Dixon [Bull. New Zealand Inst. 3: 363, 1929] is considered here to be a synonym of Kiaeria pumila (Mitt.) Ochyra.

Dicranella perfalcata E.B.Bartram & Dixon [Bot. Not. 1937: 70, 1937] was described from a Berggren collection from Ōtira Gorge, Westland L.D. The type collection is referred here to synonymy within Ditrichum brevirostre (R.Br.bis) Broth.

Dicranella temperata Allison [Trans. & Proc. Roy. Soc. New Zealand 78: 93 (1950)] was described from a single rather poor specimen from Lake Te Ānau in Southland L.D. In his decision to describe this species as a Dicranella, Allison was perhaps overly influenced by comments from Bartram (to whom a portion of the collection was apparently sent), indicating that it represented a species of Microdus unknown to him. The type collection is doubtfully dicranaceous, despite having peristome teeth that are either split into two unequal forks or elongately perforated c. ⅓ to base. The teeth appear to be paired and, in somewhat immature capsules, are completely smooth. The gametophytes are also anomalous with respect to Dicranella and are suggestive of the Pottiaceae or Zygodon (the costal cross-sections lack stereids and exhibit ± uniform cells throughout, in a manner suggestive of a Zygodon). No stomata are present in the erect, striate capsules. This name is not considered further.

Dicranella vaginata var. longifolia Dixon & Sainsbury in Sainsbury [Trans. & Proc. Roy. Soc. New Zealand 75: 171, 1945] is synonymous with Ditrichum punctulatum Mitt.