Alain Vanderpoorten

Plants small, light green to yellowish. Stems freely and irregularly branched; hyalodermis absent, central strand present; paraphyllia few; rhizoids on stem or abaxial costa insertion, rarely forming tomentum, slightly to strongly branched, smooth; axillary hair distal cells 1-4, hyaline. Stem leaves wide-spreading to squarrose, cordate-ovate, not plicate, 0.5-0.7 mm; base narrowed, decurrent, concave at basal angles; margins plane or slightly recurved in alar region, entire or nearly so, limbidia absent; apex long-acuminate, ; costa single, to 1/2-3/4 leaf length, ; alar cells differentiated, somewhat inflated, hyaline, . Sexual condition autoicous. Capsule horizontal, subcylindric, curved; peristome perfect; exostome margins dentate distally; endostome cilia nodose. Spores 9-18 µm.

Species 1: North America, Mexico, Central America, Europe.

Pseudocampylium radicale, the only species in the genus, has been placed among Campylium, Leptodictyum, and most recently, Amblystegium. Its slender habit is reminiscent of Amblystegium serpens, while its wide-spreading to squarrose leaves recall Campylium, and its fairly long laminal cells are somewhat similar to those of Leptodictyum. Molecular evidence shows that P. radicale is unrelated to these genera and is nested within a clade including similarly slender species with a weak or even absent costa, including Pseudoamblystegium subtile and Serpoleskea confervoides, but also a morphologically heterogeneous assemblage of genera including Anacamptodon and Hygrohypnum. All these taxa have fairly narrow ecological ranges, and it seems that habitat specialization has triggered an array of contrasting morphologies among taxa that share a common ancestor.

Lower Taxon

• Pseudocampylium radicale (P. Beauvois) Vanderpoorten & Hedenas