Elmeriobryum guatemalense Rohrer 1986

Elmeriobryum guatemalense

Elmeriobryum guatemalense J. R. Rohrer, Bryologist 89: 29. 1986. Type: Guatemala. San Marcos: Barranco Eminencia, road between San Marcos and San Rafael Pie de la Cuesta, in upper part of the barranco between Finca La Lucha and Buena Vista, 2500–2700 m, 6 Feb 1941, Standley 86466 (holotype: MICH; isotypes: F, FH, NY!).

Plants relatively robust, in extensive loose mats, shiny, golden brown to yellow-green. Stems to ˜10 cm, creeping, elongate, irregularly and distantly 1–2-pinnately branched; stems in cross section with 2–3 rows of small thick-walled cells surrounding abruptly larger thin-walled cells, central strand of small very thin-walled cells; pseudoparaphyllia foliose; axillary hairs consisting of 1 short brown basal cell and 2 elongate hyaline distal cells. Stem and branch leaves somewhat differentiated; stem leaves 1.0–1.8 mm long, 0.7–1.4 mm wide, erect to erect-spreading when dry, spreading when moist, broadly ovate to oblong, abruptly apiculate, concave, plicate; margins serrulate above, entire below, reflexed at base, plane or broadly inrolled above; costa double, the two forks separated at base and ± parallel, extending ¼–½ the leaf length; median cells 25–75 × 4–7 μm, narrowly elliptic to linear, smooth or sometimes minutely prorulose, basal cells wider, porose; alar cells scarcely differentiated, slightly wider than other basal cells. Branch leaves 1.0–1.5 mm long, 0.4–0.7 mm wide, ovate to elliptic, less plicate than stem leaves. Asexual propagula none. Apparently dioicous. Perichaetia unknown. Sporophytes unknown.

Distribution and ecology: Known only in Central America from Guatemala, El Salvador, and Costa Rica (Figure 2). Usually on tree trunks and branches or sometimes on leaves. Also occurring on wet banks and rocks in moist forests. At moderate to high elevations from 1800 to 3000 m.

Discussion: This little-known species was formerly confused with Leptohymenium (Hylocomiaceae), but the distinction between it and Leptohymenium was resolved by Rohrer (1986). Unlike Leptohymenium and the rest of the Hylocomiaceae, the branching in Elmeriobryum is monopodial rather than sympodial, the leaves are not at all decurrent, and the alar cells scarcely if at all differentiated. This New World species differs from its Asian counterpart, E. philippinense Broth., by having leaves more strongly plicate, with an apiculate rather than an acute apex, and a stronger costa. Also, in E. guatemalense the alar cells are more poorly differentiated than in E. philippinense.

Selected specimens examined: GUATEMALA. Guatemala: Volcán de Pacaya, Standley 80724 (F, FH, MICH, US). Quezaltenango: El Pocito, S of San Martín Chile Verde, Standley 85043 (F, MICH, NY). San Marcos: Barranco Eminencia, Standley 68524 (F, FH). Sololá:

Volcán Atitlán, Steyermark 47464 (F, FH, MICH, NY, TENN). EL SALVADOR. Santa Ana: Cerro Miramundo NW of Metapán, Carlson 962b (F, FH). COSTA RICA. Heredia: Volcán Barba, Griffin et al. D-268 (CANM, F, MO, NY).