Elegant Pseudotaxiphyllum Moss

Pseudotaxiphyllum elegans

Pseudotaxiphyllum elegans (Brid.) Z. Iwats., J. Hattori Bot. Lab. 63: 449. 1987. Hypnum elegans Hook., Musci Exot. 1: Pl. 9. 1818, hom. illeg.; Isothecium elegans Brid., Bryol. Univ. 2: 356. 1827; Isopterygium elegans (Brid.) Lindb., Not. Sällsk. Fauna Fl. Fenn. Förh. 13: 416. 1874; Plagiothecium elegans (Brid.) Schimp., Syn. Musc. Eur. ed. 2, 698. 1876. Type: Canada, British Columbia, Vancouver Is., Nootka, Menzies 35 (holotype: BM!; isotype: NY!).

Plants in thin to dense mats, glossy, dark green to yellowish green. Stems to 1 cm long, 1–2 mm wide, simple or irregularly branched. Asexual reproductive bodies usually present, clustered in leaf axils below stem apices, 0.8–1.2 mm long, yellow to green, smooth-celled, resembling the parent plant but smaller, bearing reduced leaves from apex to base of propagula. Leaves 0.5–1.2 mm long, 0.2–0.6 mm wide, semiflaccid to rigid, close to somewhat distant, erect-spreading, somewhat concave, smooth, lanceolate, ovate- or oblong-lanceolate, symmetric, acuminate; margins plane, serrulate to strongly serrate above, serrulate to entire below; costa usually strong, short and double; median cells 48–100 × 4–7 µm, smooth; apical cells sometimes minutely prorulose at upper ends on dorsal surface; alar cells undifferentiated or 1–3 quadrate to rectangular cells on margins. Sex organs and sporophytes not seen on Latin American plants. North American plants reported (Ireland, 1969) to be dioicous. Setae 1.0–2.5 cm long, dark red; capsules 1–2 mm long, cernuous to pendulous, straight or subarcuate, oblong-ovoid to ovoid, wrinkled and contracted below mouth when dry; operculum conic to short-rostrate, 0.4–0.7 mm long; annulus present. Crum and Anderson (1981) reported spores 7–10 µm in diameter, minutely roughened.

Distribution and ecology: Very rare; known from one locality on the Falkland Islands, Argentina, where it occurred on rocks, and from one in Chile, where it occurred on a limestone cliff, both localities apparently at sea level (Figure 29); known elsewhere from Canada, United States, Europe, and Iceland; reported from Asia and Africa (van der Wijk et al., 1964).

Discussion: This species is recognized by the close to somewhat distant, erect-spreading, lanceolate, ovate- or oblong-lanceolate, asymmetric, acuminate leaves with serrulate to strongly serrate margins, the narrow median leaf cells, the poorly differentiated alar cells, 1–3 marginal cells quadrate to rectangular, and the usual presence of clusters of propagula in the leaf axils below stem apices, the propagula resembling the parent plant but smaller, bearing reduced leaves from apex to base. Pseudotaxiphyllum elegans is morphologically close to P. distichaceum. For distinctions see the discussion under that species.

The Halle and Skottsberg 873 (UPS) specimen from the Falkland Islands has been reported as Isopterygium elegans var. nanum (Jur. in Milde) A. Jaeger (Cardot and Brotherus, 1923; Matteri, 1986; Matteri and Schiavone, 2002), but an examination of the specimen fits our concept of P. elegans var. elegans. The type of the var. nanum has not been examined, but judging from Juratzka’s (1864) description of the type (as Plagiothecium nanum Jur. in Milde), it falls within the range of variation that we associate with P. elegans var. elegans. Therefore, we are doubtful that the variety is worth taxonomic recognition, but the final decision will have to wait until the type of the var. nanum is examined.

Specimens examined: CHILE: Bío-Bío: Arauco Prov., 2 km N of Casa de Piedra Beach, a.s.l.[at sea level], 38°28'S, 73°31'W, Ireland & Bellolio 33252 (CONC, MO). ARGENTINA: Falkland Islands: West Falkland, Warrah River, 17 Dec 1907, Halle & Skottsberg 873 (UPS).