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Pylaisia selwynii Kindberg 1889

Comprehensive Description

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Pylaisia selwynii

Pylaisia selwynii Kindb., Ottawa Naturalist 2: 156. 1889; Pylaisiella selwynii (Kindb.) H. A. Crum, Steere & L. E. Anderson, Bryologist 67: 164. 1964. Type: Canada. Ottawa, Richmond Road, 15 May 1885, Macoun s.n. (holotype: S!; isotype: CANM!).

Plants small, in mats, glossy, yellow-green to dark green. Stems to 2 cm long, creeping, regularly pinnately branched, branches to 3 mm long, ascending and curved when dry. Leaves straight to secund, ovate, abruptly short-acuminate, stem leaves 0.9–1.2 mm long, 0.5–0.6 mm wide, branch leaves 0.7–0.9 mm long, 0.25–0.3 mm wide, not concave, not plicate; margins plane or slightly incurved above, serrulate above; costa short and double; median cells 25–45 × 4.3–7 µm, linear; alar cells oblate to short-rectangular, extending up the margins by 20–25 cells, in 6–10 rows across the insertion. Perichaetial leaves to 1.6 mm long, oblong-lanceolate, gradually long-acuminate; margins subserrulate above. Setae 10–15 mm long, yellow- to red-brown, sinistrorsely twisted in lower ½ and dextrorsely twisted in upper ½ when dry; capsules 1.0–1.6 mm long, cylindrical, reddish brown; operculum obliquely conic; exostome teeth ˜150–200 µm long, smooth below, finely papillose above; endostome adherent to exostome teeth below, free above, with a well developed, smooth, basal membrane, segments extending beyond the exostome teeth, papillose, keeled, bifid with ½ of segment plus cilium united and adherent below to exostome teeth. Spores 16–25 µm in diameter, finely papillose.

Distribution and ecology: Reaching its southern limit in western and southern Mexico (Chiapas, Chihuahua, and Oaxaca in addition to those cited below); commonly occurring in eastern North America; and also known from eastern Asia, extending into central European Russia; growing on tree trunks.

Illustrations in publications: Pl. 752 (as Pylaisiella selwynii (Kindb.) Crum, Steere & L. E. Anderson) in Ando (1994: 1013); Fig. 31 in Arikawa (2004: 120); Fig. 558 in Crum and Anderson (1981: 1134); Pl. 341 in Ireland (1982: 598).

Discussion: This North Temperate species creeps into the Neotropics in western Mexico. It is characterized by ascending and curved branches, relatively short-acuminate leaves, relatively short laminal cells, numerous alar cells, an endostome adherent to the exostome teeth, and spores intermediate in size between P. falcata and P. polyantha.

Specimens examined: Mexico. Sonora: E of El Tigre, Cañon de Santa Rosa, White 559 (UBC); Río de Bavispe, La Nacha, White 4013 (S). Sinaloa: ˜2.8 km E of Las Palmitas, along Hwy. 40, Norris 20579 (UBC).
bibliographic citation
Ireland, Robert Root and Buck, William R. 2009. "Some Latin American Genera of Hypnaceae (Musci)." Smithsonian Contributions to Botany. 1-97. https://doi.org/10.5479/si.0081024X.93