Pylaisia
in P. Bruch and W. P. Schimper, P. Bruch and W. P. Schimper, Bryol. Europ. 5: 87, plate 455. 1851.
Plants small, in low mats, yellowish to whitish, shiny. Stems creeping, regularly or irregularly pinnate, branches usually strongly curled when dry; hyalodermis absent, central strand present, small; pseudoparaphyllia foliose. Stem and branch leaves similar. Stem leaves appressed when dry, erect-spreading when moist, ovate-lanceolate, widest beyond base, not or slightly plicate; base not or weakly decurrent; margins plane, sometimes slightly involute distally, subentire to serrulate distally; apex acuminate; costa double and short or indistinct; alar cells differentiated, subquadrate to rectangular; laminal cells smooth; distal cells usually longer than 6:1. Branch leaves narrowly ovate- to oblong-lanceolate, smaller to occasionally somewhat larger than stem leaves. Specialized asexual reproduction absent. Sexual condition autoicous; inner perichaetial leaves erect, oblong-lanceolate, apex subulate. Seta yellowish or reddish. Capsule erect to suberect, oblong-cylindric to oblong-ovoid, straight, not contracted below mouth; annulus differentiated or not; operculum conic to rostrate, obliquely short- to long-acute or obtuse; peristome perfect to reduced, hygroscopic; exostome teeth with external surface smooth basally, sometimes roughly papillose distally; endostome basal membrane present, segments sometimes 2-fid or fragmentary, keeled, cilia rudimentary. Calyptra naked. Spores spheric [somewhat tetrapozoidal by endosporic protonemata], finely papillose.
Distribution
North America, Mexico, Central America, South America (Andes Mountains), Europe, Asia.
Discussion
Species 16 (4 in the flora).
Pylaisia has yellowish brown stems 2 cm long and reddish capsules; the exothecial cell walls are thin. The setae are sinistrorse-twisted basally and dextrorse-twisted distally when dry; the capsules have few phaneropore stomata on the base of the neck; and the exostome teeth are lance-subulate to blunt, distinctly lamellate, and internally trabeculate.
Selected References
Key
| 1 | Endostome free, segments neither 2-fid nor perforate; spores usually smaller than 16 µm; stem leaves usually longer than 1.3 mm | > 2 |
| 1 | Endostome wholly or partially adherent to exostome teeth, segments split, 2-fid; spores usually larger than 16 µm; stem leaves usually shorter than 1.2 mm | > 3 |
| 2 | Branches subjulaceous; stem and branch leaves slightly differentiated; alar cells 8-10 along margins; endostome 0.3 mm beyond mouth. | Pylaisia polyantha |
| 2 | Branches ± complanate-foliate, partly subjulaceous; stem and branch leaves well differentiated; alar cells 10-15 along margins; endostome 0.4-0.5 mm beyond mouth. | Pylaisia steerei |
| 3 | Endostome free distally; stems regularly pinnate; alar cells 20-25 along margins. | Pylaisia selwynii |
| 3 | Endostome wholly adherent; stems irregularly pinnate; alar cells 6-12 along margins. | Pylaisia intricata |