Lars Hedenas

Plants small to large, green or yellowish green. Stems pinnate ± in one plane or irregularly branched to almost unbranched; hyalodermis present, central strand present; paraphyllia absent; rhizoids or rhizoid initials on stem or abaxial costa insertion, rarely forming tomentum, slightly branched, smooth; axillary hair distal cells 1-8, hyaline. Stem leaves crowded, circinate, falcate, or almost straight, lanceolate, plicate or rarely not, 0.3-1.7 mm wide; base not or hardly decurrent; margins sometimes incurved proximally, plane or recurved distally, finely denticulate or entire proximally, very finely to strongly denticulate distally, limbidia absent; apex acuminate to very long-acuminate; costa single, ending in acumen; alar cells differentiated, short- to long-rectangular, inflated, hyaline, region transversely triangular or ± isodiametric; medial laminal cells linear; marginal cells 1-stratose. Sexual condition autoicous. Capsule horizontal, erect, or inclined, cylindric or short-cylindric, curved to straight; peristome perfect or specialized; exostome teeth with margins dentate distally; endostome cilia well developed, rudimentary, or absent. Spores 10-21 µm.

Species 4 (4 in the flora): North America, Mexico, South America, Eurasia, Africa, Atlantic Islands, Pacific Islands (New Zealand), Australia, Antarctica.

Sanionia is characterized by its well-developed hyalodermis, plicate leaves, hyaline, thin-walled, inflated alar cells forming a transversely triangular or more or less isodiametric group, sometimes prorate distal cell ends on the abaxial lamina, and, except in the strongly specialized S. nivalis, very long-acuminate inner perichaetial leaves. Except for S. nivalis, the species generally occur in drier habitats than members of, for example, Drepanocladus, Scorpidium, or Warnstorfia. The other members of the traditional, widely circumscribed genus Drepanocladus in the broad sense that are most closely related to Sanionia are now placed in Drepanocladus and Pseudocalliergon; the latter two genera lack a hyalodermis, have 1-3 rather than 1-8 distal cells of the axillary hairs, and have generally non-plicate rather than plicate leaves. However, because some small phenotypes of Sanionia may also have nearly to entirely non-plicate leaves, the last character should be used with caution. The structures of the alar regions are different, and the exostome margins are more weakly dentate than in S. uncinata, which is the only Sanionia species with an unspecialized peristome. Features separating Sanionia from Hamatocaulis, Loeskypnum, Sarmentypnum, Scorpidium, or Warnstorfia are pointed out in the discussion of 61. Calliergonaceae.

Lower Taxa

• Sanionia nivalis Hedenas
• Sanionia orthothecioides (Lindberg) Loeske
• Sanionia symmetrica (Renauld & Cardot) Wheldon
• Sanionia uncinata (Hedwig) Loeske