Taxiphyllum laevifolium W. R. Buck 1987

Taxiphyllum laevifolium

Taxiphyllum laevifolium (Mitt.) W. R. Buck, Mem. New York Bot. Gard. 45: 521. 1987. Ectropothecium laevifolium Mitt., J. Linn. Soc., Bot. 12: 517. 1869. Type: Colombia, Andes Bogotenses, Weir 425 (holotype: NY!).

Glossadelphus laevifolius (Mitt.) E. B. Bartram, Bull. Brit. Mus. (Nat. Hist.), Bot. 2: 49. 1955.

Plants in thin to dense mats, glossy, light green to yellow-green. Stems usually ˜2 cm long, rarely to 7 cm, 1.5–2.0 mm wide, complanate-foliate, usually irregularly branched. Leaves 0.8–1.5 mm long, 0.4–0.7 mm wide, rigid, imbricate, erect to erect-spreading, slightly concave, smooth, ovate- to oblong-lanceolate, symmetric, or somewhat asymmetric, acute to obtuse, the apices broad, irregularly notched with the cells ending at different levels; margins plane, serrate to serrulate above, sometimes the serrations bifid at leaf apices, serrulate to entire below; costa lacking or weak, short and double; median cells 38–80 × 5–6 µm, smooth or often prorulose at upper ends on dorsal surface; alar cells poorly differentiated, long- to short-rectangular or rarely quadrate, in a few rows with 1–4 cells in the marginal rows. Synoicous. Setae 1.2–1.5 cm long, red, flexuose; capsules 0.7–1.0 mm long, inclined, straight or nearly so, ovoid, often contracted below mouth when dry; operculum unknown; annulus present, persistent. Spores 23–28 µm in diameter.

Distribution and ecology: Rare or seldom collected; Mexico, Panama, Jamaica and Colombia (Figure 33); occurring on lava boulders, rocks in woods, beside streams and near waterfalls or on trunks of fallen trees, at ˜700–1300 m. Also reported from Costa Rica, Galápagos Iss., Cocos Iss., and Dominica (Crum, 1994a, as Glossadelphus laevifolius).

Discussion: This species is distinguished by the rigid, light to yellow-green, complanate-foliate plants, the imbricate leaves that are erect to erect-spreading, slightly concave, ovate- to oblong-lanceolate with plane margins, acute to obtuse apices that are often irregularly notched with the cells ending at different levels, the serrate leaf margins at apices sometimes bifid and the poorly differentiated alar regions of a few rows of short-rectangular or rarely quadrate cells with 1–4 differentiated cells in the marginal rows.

The leaf margins in this species sometimes have bifid serrations on the apical leaf cells which is very unusual and it was only observed in the single collection from Veracruz, Mexico. This morphological feature was noted by H. A. Crum (1994a), who placed the species in the genus Glossadelphus. However, the illustration in Crum (1994a: fig. 747e) does not show the bifid teeth; they are instead shown for G. ligulaefolius (Crum, 1994a: fig. 747b). This is undoubtedly an error in the illustration of the species since the description states that G. laevifolius has “serrations often minutely bifid.” However, the Mexican plants may have much larger bifid serrations than shown in the illustration (see collection from Veracruz, Mexico, at TENN). No other species of Taxiphyllum is known to have bifid serrations from Latin America or, as far as we know, from anywhere else in the world. This could be a reason for placing this species in another genus, but further study is necessary to decide whether it belongs in Glossadelphus or another genus. Also, although Crum indicates that G. laevifolius does not have prorulae on cells on the dorsal surface of the leaf, we have found that they are often present.

Although the type collection (NY) from Colombia was described as monoicous, the senior author was unable to find any antheridia on plants with sporophytes when the specimen was examined. The only Jamaican collection contained plants with synoicous inflorescences but with no sporophytes. Synoicous pleurocarpous mosses are usually rare, with the exception of members of the Hookeriales, and only a very small number of species in other orders are known with this sexual condition.

Specimens examined: MEXICO. Veracruz: Road to Bastonal, above Tebanca, 700 m, Richards, A.J. & E.B. Sharp 5863b (TENN). PANAMA. Bocas del Toro: Vicinity of Fortuna Dam, along ridge below Continental Divide on Chiriqui Grande road, 800 m, 08°55'N, 82°08'W, Allen 5831 (MO). JAMAICA. Portland: Forest Reserve Area W of Hardwar Gap, 1219–1295 m, Crosby 2923 (DUKE). COLOMBIA. Known only from the type locality.