Plants pale olive to dark green, somewhat small, soft, pale green or yellowish green. Primary stems creeping; leaves appressed to erect, lanceolate, to 1 mm long, acuminate. Secondary stems usually pendent, freely branching; central strand absent. Leaves erect-spreading, ovate to short obovate, (0.5–)1–1.4 mm long, deeply concave, acute to short acuminate, base weakly auriculate; margins plane, serrulate mostly 1/2–1/3 lamina length; costa absent, rarely weakly short and either single or double; laminal cells smooth, median cells linear, ± vermicular; apical cells short; basal cells golden-yellow; alar region weakly differentiated, cells few, subquadrate to short oblong-rectangular, golden-yellow. Dioicous. Perichaetial leaves sheathing, oblong-acuminate, to 2 mm long. Setae rather short, to 4.3 mm long, ± curved, smooth, yellow to pale orange-yellow. Capsules exserted, erect, urn ovoid, to 1.2 mm long; opercula conic-rostrate, oblique; peristome with exostome teeth papillose; endostome basal membrane low, segments narrow, papillose, perforate to base. Calyptrae not observed. Spores papillose.

Plantas verde oliva pálidas hasta oscuras, algo pequeñas, suaves, verde pálidas o verde amarillentas. Tallos primario reptantes; hojas adpresas hasta erectas, lanceoladas, hasta 1 mm de largo, acuminadas. Tallos secundarios generalmente pendientes, ocasionalmente dendroides, libremente ramificados; sin cordón central. Hojas erecto-extendidas, ovadas hasta corto obovadas, 1–1.4 mm de largo, profundamente cóncavas, agudas hasta corto-acuminadas, base indiferenciada hasta redondeada o auriculada; márgenes planos, distalmente serrulados hasta subenteros; costa débilmente corta,  simple, bifurcada y algunas hojas sin costa; células de la lámina lisas, células mediales lineales, ± vermiculares; células apicales cortas; células basales a menudo amarillo-doradas; región alar débil hasta conspicuamente diferenciada, células subcuadradas hasta corto oblongo-rectangulares, algunas veces amarillo-doradas. Dioicas. Hojas periqueciales envainadoras, oblongo-acuminadas, hasta 2 mm de largo. Setas bastante cortas, hasta 4.5 mm de largo, ± curvadas y lisas. Cápsulas excertas, erectas, urna ovoide, hasta 1.2 mm de largo; opérculo cónico-rostrado, oblicuo; peristoma con dientes del exostoma papilosos; membrana basal del endostoma baja, segmentos angostos, papilosos, perforados en la base. Caliptra no observada. Esporas papilosas.

Keys adapted from Allen & Magill (2007).

1. Plants with deciduous leaves … O. pachygastrella

1. Plants without deciduous leaves … 2.

2. Branch leaves straight or somewhat rounded to the insertion … O. versicolor

2. Branch leaves strongly rounded or auriculate to the insertion … 3.

3. Stems weakly branched; stem and branch leaves strongly clasping and auriculate at base; stem and branches julaceous-foliate … O. muelleri

3. Stems strongly branched; stem and branch leaves spreading and moderately auriculate at base; stem and branches not julaceous-foliate … O. rigida