Dioicous. Plants small, branched, prostrate, 8–12 (–20) mm long, pale green to dull dark green. Leaves strongly crisped to twisted when dry, ±straight when moist, ovate-orbicular to ±rounded, 0.9–1.2 mm long, 0.45–0.58 mm wide; apiculus short, stout; margin plane, distantly serrate in the upper half; costa reddish brown, extending for (50–) 65–75% of the leaf length, c. 3 cells wide, 12–20 μm wide at the base. Laminal cells moderately thick-walled; upper and median cells hexagonal to irregularly hexagonal, 12–18 × 7–12 μm, more irregular towards the margin; basal cells oblong, 20–50 × 15–25 μm, narrowly rectangular and c. 50 × 10 μm nearer the margin; border 2 or 3 cells wide, often appearing wider at the base, with cells to 100 μm long. Rhizoids arising along the stem, smooth, c. 0.35 mm long, 12–25 μm wide; cells c. 160 μm long.

Perigonial leaves ovate to oblong, c. 700 μm long. Perichaetial leaves 0.85–1.10 mm long, 0.45–0.58 mm wide, ecostate, or the costa very weak; margin distantly and weakly dentate. Laminal cells hexagonal, 37–50 × 12–20 μm; median cells more irregular; basal cells more rectangular; border narrow, 1 or 2 cells wide, grading into median cells. Calyptra c. 1.5 mm long, the tip blackish and either smooth or with erect hairs. Seta smooth, 5.8–12.5 mm long. Capsules pendulous, dark brown, narrowly oblong to oblong-oval, 0.81–1.00 mm long; operculum erect, c. 0.45 mm long. Peristome: exostome teeth yellowish brown, lanceolate, 225–270 μm long, c. 50 μm wide at the base, striolate; ventral lamellae projecting laterally; endostome segments c. 180 μm long, hyaline. Spores ±smooth, (8–) 12–15 μm diameter.

Some collections can be difficult to identify when teeth are lacking, but the rounded and strongly curved leaves with a short stout apiculus are diagnostic. The leaves are often so strongly curled, especially in Tasmanian collections, that the reddish stems are visible in dried material. Moreover, the apiculus consists mainly of cells similar to those of the upper lamina, and not elongate marginal cells as in Distichophyllum crispulum.

Fertile collections were scarce, and were usually seen in December and January.

Known from south-eastern New South Wales, Victoria and Tasmania; occurs in Nothofagus forest, temperate rainforest and wet-sclerophyll and disturbed forests; especially on wet rocks and logs. Also in New Zealand and Chile.

Hookeria rotundifolia Hook.f. & Wilson, London Journal of Botany 3: 551 (1844); Mniadelphus rotundifolius (Hook.f. & Wilson) Müll.Hal., Synopsis Muscorum Frondosorum  2: 21 (1850); Distichophyllum rotundifolium (Hook.f. & Wilson) Müll.Hal. & Broth., Abhandlungen Herausgegeben vom Naturwissenschaftlichen Verein zu Bremen 16(3): 506 (1900). 
Type: Bay of Islands, New Zealand, coll. unknown; holo: BM.

Taxonomic synonyms

Mniadelphus beccarii Hampe & Geh., Revue Bryologique 8: 26 (1881); Distichophyllum beccarii (Hampe & Geh.) Paris, Index Bryologicus 388 (1895). T: Mt Wellington, Tas.; n.v.

Mniadelphus subminutifolius Broth. & Geh., Revue Bryologique 24: 77 (1897); Distichophyllum subminutifolium (Broth. & Geh.) Müll.Hal. ex M.Fleisch., Hedwigia 63: 214 (1922). T: Clyde Mountain, N.S.W., 1888, W.Baüerlen 116; lecto: MEL, fide H.Streimann, Journal of the Hattori Botanical Laboratory 86: 107 (1999).

Distichophyllum fissidentoides Müll.Hal., Hedwigia 41: 122 (1902). T: “Mossman’s Bay”, [Sydney], N.S.W., Sept. 1884, T.Whitelegge; lecto: H, fide H.Streimann, loc. cit.; isolecto: BM.

Distichophyllum obliquomucronatum Müll.Hal., Hedwigia 41: 122 (1902). T: Fern Tree Gully, Mt Wellington, Tas., 10 Feb. 1888, W.A.Weymouth; holo: n.v.; iso: H.

Distichophyllum squarrosulum Müll.Hal., Hedwigia 41: 122 (1902). T: Cambewarra, N.S.W., Dec. 1885, T.Whitelegge; holo: n.v.; iso: H.

N.S.W.: Balls Head Bay, T.Whitelegge 2708 (NSW); Mongarlowe R., 22 km SE of Braidwood, H.Streimann 39547 (CANB, H).

Vic.: Errinundra Rd, 24 km S of Bendoc, J.A.Curnow 1784 (CANB); Grand Ridge–Mt Fatigue road, Strzelecki S.F., 13 km NE of Foster, H.Streimann 51740 (Musci Austral. Exs. 269) (CANB).

Tas.: Gordon River, Macquarie Harbour, T.B.Moore 53  (H, HO).

J.Beever, K.W.Allison & J.Child, Mosses of New Zealand, 2nd edn 131 (1992); H.Streimann, Journal of the Hattori Botanical Laboratory  86: 112, fig. 13 (1999).

Streimann, H. (2012). Australian Mosses Online 11. Hookeriaceae: [Distichophyllum]. Australian Biological Resources Study, Canberra. Version 19 April 2012