From the Greek scleros (hard) and odontion, the dimunitive of odous (a tooth), presumably in reference to some property of the peristome teeth.

Dioicous. Plants dull green, forming rough mats. Stems creeping, with ascending tips, and with many erect mainly monopodial innovations, reddish brown, densely foliose, lacking tomentum; central strand present. Leaves ovate-lanceolate to narrowly ovate-lanceolate, canaliculate, occasionally subtubulose near the apex, frequently ending in a hyaline hair-point or swollen clavate gemma, when dry often slightly rugose; alar patches differentiated; margin entire throughout; border consisting of up to 4 (–8) rows of linear hyaline cells; costa subpercurrent to excurrent, in cross section with 4 guide cells and 1 or 2 layers of stereids on either side. Upper laminal cells isodiametric, irregularly shaped because of mostly strongly pitted walls, papillose at least abaxially, descending along the margins; basal juxtacostal cells elongate to linear, thick-walled, pitted, smooth; alar cells brown, with strongly thickened lateral walls.

Sclerodontium differs from the closely related but much more speciose Leucoloma by the quadrate, papillose, upper laminal cells that descend along the margins, rather than along the costa, and by the asymmetrical to curved capsules.

Sclerodontium includes 2 species occurring in southern Malesia, Australasia, New Caledonia, Brazil and the Kerguelen Islands (Indian Ocean).

Sclerodontium Schwägr., Sp. Musc. Frond., Suppl. 2, 1: 124 (1824). Type: S. pallidum (Hook.) Schwägr.

Leucoloma sect. Dicnemoloma Renauld, Prodr. Fl. Bryol. Madagascar 61 (1898); Leucoloma sect. Dicnemoloma (Renauld) Paris, Index Bryol., Suppl. 1: 115 (1900); Dicnemoloma (Renauld) Renauld, Rev. Bryol. 28: 86 (1901). Type: L. sieberianum (Spreng.) A.Jaeger [= S. pallidum (Hook.) Schwägr.]

Sclerodontium fits comfortably in the Dicranaceae due to its asymmetrically split peristome teeth and its differentiated, strongly coloured alar patches. However, the creeping growth form is anomalous here, being more reminiscent of Racomitrium (Grimmiaceae) or Hedwigia and Hedwigidium (Hedwigiaceae).

Key to species

Leaves ending in a swollen deciduous tip; laminal cells adaxially smooth, except those near apex and on gemmae (with stellate papilla) .............. S. clavinerve Leaves not ending in a deciduous tip; laminal cells adaxially with multiple simple papillae close to the walls; laminal cells near apex with a simple curved papilla .......................... S. pallidum

Crum, H.A. (1986). A survey of the moss genus Sclerodontium. Hikobia 9: 289–295.

Klazenga, N. (2012). Australian Mosses Online 33. Dicranaceae. (Australian Biological Resources Study: Canberra). Version 30 May 2012; https://www.anbg.gov.au/abrs/Mosses_online/33_Dicranaceae.html [Accessed July 2019]

Klazenga, N. (2012). Australian Mosses Online 33. Dicranaceae. (Australian Biological Resources Study: Canberra). Version 30 May 2012; https://www.anbg.gov.au/abrs/Mosses_online/33_Dicranaceae.html [Accessed July 2019]