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Published In: Journal of the Hattori Botanical Laboratory 39: 519. 1975. (J. Hattori Bot. Lab.) Name publication detail

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This species has commonly been called Barbula bescherellei in Central America. It was first treated by Zander (1978b) as a synonym of Didymodon acutus, Crum & Anderson (1981) called it Barbula acuta var. bescherellei. More recently (Zander 1981, 1994a, 1998) the Central American taxon has been included in Didymodon rigidulus Hedw. Due to the taxonomic confusion surrounding this taxon the world range given above is incomplete.

Didymodon acutus is fairly common in Central America as would be expected for a moss found in such a wide range of habitats. The leaves of D. acutus characteristically have weakly differentiated upper and lower leaf cells that are smooth or weakly unipapillose, margins recurved to near mid-leaf, and more or less plane apices. Its costa fills the leaf apex, is excurrent into a stout subula and has quadrate cells on upper ventral surface. Didymodon rigidulus differs from D. acutus in having oblong- to long-triangular leaves with thickened, bistratose upper leaf margins, a blunt, percurrent to short-excurrent costa, axillary propagula, and straight or only weakly twisted peristome teeth. Didymodon icmadophilus differs from D. acutus in having shorter, narrower, leaves that are contacted to a long, stoutly excurrent costa, plane leaf margins, and somewhat smaller, smooth, essentially uniform leaf cells. Didymodon vinealis differs from this species in having leaves with a narrow median channel above, percurrent costae with guide cells in the lower part of the leaves in 1–2 rows, and pluripapillose upper leaf cells.

Didymodon acutus often has the field aspect of Ceratodon or Dicranella and microscopically its often smooth leaf cells can cause confusioconfusion with those genera. Neither genus, however, has the stoutly excurrent costa of D. acutus, while the quadrate, sharply angled leaf cells of Ceratodon and the long, sharply angled leaf cells of Dicranella are not encountered in Didymodon acutus.

Illustrations: Grout (1938, Pl. 88 A as B. bescherellei); Bartram (1949, Fig. 55 A–D as B. bescherellei, Fig. 57 A–D as B. teretiuscula); Crum and Anderson (1981, Fig. 157 as B. acuta var. bescherellei); Sharp et al (1994, Fig. 223 as D. rigidulus var. gracilis); Ku_era (2000, Fig 1).  Figure 20.
Habitat: On moist or dry, shaded soil or banks, also wet cliffs, boulders, logs, trees, and old masonry; 800–3300 m.
Distribution in Central America: GUATEMALA. Alta Verapaz: Johnson 799 (NY, US); Baja Verapaz: Sharp 2797 (FH, MO); Chimaltenango: Godman & Salvin (NY); Huehuetenango: Standley 82106 (F, FH, MO, NY); Quezaltenango: Standley 85975 (F, FH, NY); Quiché: Sharp 5290 (MO); Sacatepéquez: Standley 59017 (F, FH); San Marcos: Sharp 2630 (US); Santa Rosa: Bernoulli 657 (NY); Sololá: Svihla 2888a (FH); Totonicapán: Standley 83127 (F, FH, NY). EL SALVADOR. Ahuachapan: Winkler 31b (MO).  NICARAGUA. Managua: Standley 8650 (F, FH). HONDURAS. Cortés: Olson 84-45b (MO); Francisco Morazán: Allen 17785 (MO, TEFH). COSTA RICA. Alajuela: Brenes 20305 (FH, NY); Cartago: Dauphin 2073 (MO); Heredia: Holz & Schäefer-Verwimp CR99-1332 (GOET, MO); San José: Standley 42613 (FH, NY, US). PANAMA. Chiriquí: Gentry 6044 (MO, PMA); Coclé: Salazar et al. 941 (BUF, MO).
World Range: Southwestern and South-Central U.S.A.; Mexico; Central America.


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Didymodon acutus (Brid.) Saito, J. Hattori Bot. Lab. 39: 519. 1975.

Tortula acuta Brid., Muscol. Recent. Suppl. 1: 265. 1806. Barbula acuta (Brid.) Brid., Muscol. Recent. Suppl. 4: 96. 1819. Protologue: Switzerland and Germany. In Heluetiâ et Germaniâ passim lecta est, et mecum sub variis nominibus vt Tortula rigidula, neruosa etc. communicata.

Barbula teretiuscula Schimp. ex C. Müll., Syn. Musc. Frond. 1: 614. 1849. Tortula teretiuscula (Schimp. ex C. Müll.) Mitt., J. Linn. Soc., Bot. 12: 160. 1869. Protologue: Mexico. Mexico, ad montem Orizaba: Liebmann.

Barbula gracilescens Schimp. ex Besch., Mém. Soc. Sci. Nat. Cherbourg 16: 178. 1872. Protologue: Mexico. Vera Cruz, 1853 (F. Müller in herb Schimper).

Barbula graciliformis Schimp. ex Besch., Mém. Soc. Sci. Nat. Cherbourg 16: 179 1872. Protologue: Mexico. Prope San Nicolas, in valle Mexicensi (Bourg. n° 1355).

Barbula rigidula Besch., Mém. Soc. Sci. Nat. Cherbourg 16: 180 1872, hom. illeg., non B. rigidula (Hedw.) Mild., 1869. Protologue: Mexico. Prope Guadalupe, e valle Mexicensi (Bourg. n° 1321, pro parte).

Barbula bescherellei Sauerb. ex Jaeg., Ber. Thätigk. St. Gallischen Naturwiss. Ges. 1877-78: 409. 1880, nom. nov. for B. rigidula Besch. Barbula acuta var. bescherellei (Sauerb. ex Jaeg.) Crum, Bryologist 72: 241. 1969. Protologue: Mexico. Prope Guadalupe, e valle Mexicensi (Bourg. n° 1321, pro parte)

Barbula costaricensis Ren. & Card., Bull. Soc. Roy. Bot. Belgique 31(1): 154. 1892. Protologue: Costa Rica. Sur une pierre, dans un pâturage près de l’hospice des aliénés Pitt. n° 5533 (PC). Syn. nov.

Barbula godmaniana C. Müll., Bull. Herb. Boissier 5: 193. 1897. Didymodon godmanianus (C. Müll.) Bartr., Bryologist 49: 113. 1946. Protologue: Guatemala. Guatemala, Volcan de Fuego: Godman et Salvin (NY).

Barbula lagunicola C. Müll., Bull. Herb. Boissier 5: 194. 1897. Protologue: Guatemala. Laguna del Pino. [Bernoulli & Cario] Coll N° 114 (NY).

Plants small, medium or robust, dull, green to yellow-green above, brown below, in tufts,  5–60 mm high. Stems red to reddish yellow, erect, sparsely and irregularly branched, sclerodermis  and central strand present; rhizoids sparse, at base of stems or scattered throughout. Axillary hairs 3–5 cells long, basal cell brown. Leaves 0.85–2.6 mm long, lanceolate, broadly ovate-lanceolate, or triangular-lanceolate, not clasping at base, crowded or well-spaced on stems, erect-incurved when dry, wide-spreading when wet, plane or broadly concave on ventral surface; apices sharply acute to subulate; lamina unistratose or bistratose along the margins; margins entire, revolute below, plane above; costa filling the apex and stoutly excurrent, surface ventral cells of costa quadrate, guide cells present, ventral stereid cells absent or poorly developed, dorsal stereid cells poorly developed, ventral and dorsal surface layers somewhat enlarged; upper and basal cells weakly differentiated, upper cells rounded-quadrate or oblate, 4–9 x 6–10 μm, firm-walled, smooth, or weakly unipapillose, basal cells oblate, quadrate, rounded or short-rectangular, firm-walled, smooth, 6–20 x 6–8 μm, extreme basal cells enlarged to 24 x 8 μm, alar cells not differentiated. Dioicous. Perichaetia and perigonia terminal; perigonia gemmiform; perichaetial leaves erect, longer, costa more excurrent than in vegetative leaves. Setae smooth, 6–18 mm long, red; capsules long-cylindrical, erect, 1.5–3.0 mm long, smooth; exothecial cells short-rectangular, firm-walled; stomata in neck; opercula erect, long-rostrate, 0.8–1.8 mm long; annuli well-developed; peristome red-orange to hyaline, teeth long and twisted, basal membrane low. Spores 8–12 μm, smooth. Calyptrae cucullate, 2 mm long.



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