Tropicos | Name - Leptodontium exasperatum Cardot

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Leptodontium exasperatum Cardot

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Project data (Last Modified On 2/16/2011)

Discussion:

Leptodontium exasperatum is closely related to L. ulocalyx as judged by its radiculose, sclerodermous stems and leaves that are strongly crispate-contorted when dry, have collenchymatous upper leaf cells, and a differentiated alar region. It also shares with L. ulocalyx blunt marginal leaf dentations made of short, pluripapillose cells, homogeneous upper leaf cells, and differentiated inner basal leaf cells that are papillose throughout. Leptodontium exasperatum differs from L. ulocalyx in having long, single, columnar papillae centered over the upper cell lumina rather than low, multiple papillae scattered over the lumina. Although the basal leaf regions of L. exasperatum and L. ulocalyx are microscopically identical, when examined with a hand-lens those of L. exasperatum often have a shiny, iridescent aspect similar to that of L. capituligerum and L. syntrichioides. Leptodontium capituligerum differs from L. exasperatum in having a stem hyalodermis. Leptodontium syntrichioides differs from L. exasperatum in having broader leaves, often subobtuse apices, evenly thickened upper leaf cells, weakly or not porose basal leaf cells, and in having coroniform rather than columnar leaf cell papillae.

Zander (1972) treated L. exasperatum as a variety of L. viticulosoides because of variability in the height of its leaf papillae and the presence of homosporous and heterosporous collections of L. viticulosoides.

Illustrations: Zander (1972, Figs. 9, 82–86); Sharp et al. (1994, Fig. 196 e). Figure 40.

Habitat: On tree stump, rotting logs, and tree bark (Juniperus, Quercus); 2250–3200 m.

Distribution in Central America: GUATEMALA. Huehuetenango: Vogel B8980 (MO, TENN); Quezaltenango: Sharp 2258 (MO, TENN); Totonicapán: Standley 62664a (FH). COSTA RICA. Cartago: Bowers 824 (TENN); Puntarenas: Angulo 246 (MO); San José: Croat 32883 (BM, CR, DUKE, F, FH, MEXU, MICH, MO, NY, US). PANAMA. Chiriquí: Sytsma & Stevens 2157 (MO, NY, PMA, US).

World Range: Mexico; Central America; Western South America.

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Leptodontium exasperatum Card., Rev. Bryol. 36: 74. 1909.

Leptodontium viticulosoides (P. Beauv.) Wijk & Marg. var. exasperatum (Card.) Zand., Bryologist 75: 254. 1972. Protologue: Mexico. Etat de Vera-Cruz: Orizaba (F. Müller). Sans indication de localité (Diguet, in herb. Mus. Paris). Lectotype (Zander 1972): Müller, s.n. (NY).

Plants medium to robust, in loose tufts, yellow-green to light green, to 9 cm high. Stems red, erect or laxly ascending, sclerodermis present, moderately to densely radiculose. Leaves moderately spaced, erect at base, spirally twisted to contorted above when dry, squarrose to squarrose-recurved when wet, ovate-lanceolate to long-lanceolate, 3–5 mm long, keeled above, sheathing at base, decurrent; apices acute; margins recurved in lower 1/2–2/3, dentate in upper 1/3, teeth pluripapillose; costa subpercurrent, usually with high papillae on upper dorsal surface; upper leaf cells quadrate to hexagonal, thick-walled, collenchymatous, 7.5–12.5 μm, with long, single, columnar, simple to bifid papillae, 4–10 μm high, centered over the lumina, inner basal cells long-rectangular to elongate, 30–100 x 5–8 μm, pluripapillose, thick-walled, porose, outer basal leaf cells similar to upper leaf cells, alar cells subrectangular to quadrate, thick-walled, porose, yellow-red. Sporophytes not seen from Central America, description based on Peruvian plants (Allen 4327, MO). Dioicous (?). Setae straight to flexuose, 1 per perichaetium, 10–15 mm long, yellow, becoming brownish with age. Capsules erect, narrowly cylindrical, 3–4 mm long, smooth when dry; exothecial cells short-rectangular, firm-walled; stomata at base of urn; opercula erect, conic-rostrate, 1.5 mm long; peristome teeth linear, divided to the base, red-brown, obliquely striate to slightly papillose on outer surface. Spores heterosporous, 5–10 μm and 12.5–15 μm, slightly papillose. Calyptrae cucullate, smooth, 5–6 mm long.