Stems 2-pinnate, stems and branches papillose; paraphyllia (1--)2--4(--5) cells long, cells ca. 1:1, all strongly papillose. Stem leaves slightly incurved when dry, ovate-triangular, 0.2--0.35 mm, acuminate; costa about 3/4 the leaf length. Branch leaves erect-incurved when dry, 0.2--0.3 mm on primary branches, ca. 0.15 mm on secondary branches, acute to short-acuminate; costa 1/2--3/5 the leaf length, straight, not covered with quadrate cells. Perichaetial leaves serrulate above, subentire below. Seta smooth; endostomial cilia in pairs.

Capsules mature July--Sept. Moist woods, growing over moist rocks, usually limestone but less often sandstone and quartzite; mostly at moderate to low elevations; Ont., Que.; Ala., Ark., Conn., Fla., Ga., Ill., Ind., Iowa, Ky., Mass., Mo., N.C., N.J., N.Y., Ohio, Okla., Pa., Tenn., Va., Vt. Wis.; Asia (China, Japan, Korea).

This is our smallest species of Cyrto-hypnum. The diminutive stature coupled with papillose stems and branches is distinctive. It is most likely confused with Heterocladium macounii, which also has pluripapillose leaf cells and papillose stems and branches. However, that species is larger and has a costa ending near or below midleaf and is without paraphyllia; although there are pseudoparaphyllia they have pointed terminal cells, not truncate as in the paraphyllia of C. pygmaeum.