Hampeella Müll.Hal.

Plants pale green, slender to moderately robust. Primary stems weak. Secondary stems (shoots) arising in tufts, ascendant, simple or sparsely branched, weakly complanate or ± julaceous, with rhizoids restricted to base, in cross-section oval. Leaves of secondary shoots imbricate, complanate or erect-spreading and ± julaceous, asymmetrically lanceolate and acute or symmetric, elliptic, and abruptly acute, serrulate above or nearly entire, neither decurrent nor plicate; mid laminal cells linear-rhombic, firm- or ± thin-walled, not or slightly porose. Costa absent or very short (<⅕ of leaf length), double, and indistinct. Paraphyllia absent. Gemmae acicular and multi-septate, arising in tufts from short rhizoid-like structures in leaf axils.

Dioicous. Perichaetia scattered on secondary shoots, the leaves expanding after fertilisation and clasping the seta base. Perigonia bud-like, on well-developed ♂ shoots (seen only in H. alaris). Capsules erect, symmetric, ellipsoid-cylindric, strongly ribbed; exothecial cells rounded and ± polygonal; stomata few at capsule base; annulus weakly developed; operculum rostrate from a conic base. Peristome double; exostome teeth bordered, cross-striate on outer surface, densely trabeculate but otherwise nearly smooth on inner surface; endostome from a pale membrane c. half the exostome height; segments smooth, nearly the height of the teeth. Calyptra not seen. Spores single celled.

The genus is circumscribed here based on the type species (which is a taxonomic synonym of H. pallens (Sande Lac.) Fleisch.) and H. alaris; material of neither H. leptodictyon from Mindinao nor H. concavifolia Hattaway & D.H. Norris from Queensland (Hattaway & Norris 2008) has been seen. This is a small genus of two to four species. Milne & Klazenga (2012) accepted three species for Australia.

The Australasian H. alaris differs from H. pallens in many gametophytic features, enumerated below. Hampeella alaris is retained in the present genus as a taxonomic convenience rather than from conviction. The tendency for the upper shoots of H. alaris to become complanate, similar gemmae form, and sporophyte morphology (excepting exostome teeth form) argue for the species’ continued placement in Hampeella. Also, W.R. Buck (pers. comm., March 2002) informed me that molecular data suggest that the two species are closely allied.