Macromitrium cirrosum (Hedw.) Brid.

Authority

Sharp, Aaron J., et al. 1994. The Moss Flora of Mexico. Part Two: Orthotrichales to Polytrichales. Mem. New York Bot. Gard. 69 (2)

Family

Orthotrichaceae

Scientific Name

Macromitrium cirrosum (Hedw.) Brid.

Description

Species Description - Plants robust, dull to glossy, yellow- to light-green above, rusty-brown below, in dense, spreading mats. Stems creeping, tomentose, with erect-ascending branches up to 4 cm high. Leaves loosely and irregularly twisted-crisped when dry, stiffly spreading from a recurved base and ± flexuose to wide-spreading and squarrose w h e n moist, 2-4(-1) mm long, keeled, linear-lanceolate to lanceolate, slenderly acute to acuminate; margins entire below, subentire or serrulate in the upper portion, ± reflexed to tightly recurved in the lower portion, plane to reflexed above; costa ending in or a few cells below the apex, rarely excurrent; upper cells 5—10(—12) µm wide, elliptic to rounded-quadrate, smooth to bulging, some cells of each leaf longer than wide, at midleaf 10-13 µm, hexagonal to elliptic-rectangular, not or in indistinct longitudinal rows; basal cells narrowly rectangular, thick-walled, with distinctly sinuose and nodose lumina, some cells tuberculate-papillose, often some leaves in each population smooth and non-tuberculate, particularly toward the costa, outer rows of cells elongate-linear and smooth, with a few marginal cells hyaline, forming a short, entire border. Pseudautoicous (with dwarf male plants on leaves). Perichaetial leaves lanceolate, acuminate, about 2.2-4 mm long; cells elongate, smooth. Setae 8-16 mm long, usually flexuose, smooth; capsules 1.1-2 mm long, obovoid to oblong-ovoid, often contracted to the seta through a ± wrinkled neck, smooth or lightly (rarely distinctly) 8-plicate; annulus not seen; exothecial cells rounded-quadrate to elliptic-rectangular, about 1-2:1, thick-walled; stomata common in the neck; exostome a low, densely papillose membrane of 16, truncate teeth; endostome a sparsely papillose, hyaline membrane. Spores anisosporous, 17-18(-25-)40-42 µm. Calyptrae naked or with a few hairs, deeply laciniate, smooth.

Discussion

Fig. 473

M. cirrosum (Hedw.) Brid., Bryol. Univ. 1: 316. 1826.

Anictangium cirrosum Hedw., Sp. Muse 42. 1801.

Orthotrichum cirrosum (Hedw.) Hook. & Grev., Edinburgh J. Sci. 1: 130. 1824.

Macromitrium costaricense Bartr., Contr. U. S. Natl. Herb. 26: 88. 1928.

The Macromitrium cirrosum complex is represented in Mexico by M . cirrosum and M . longifolium fund M. schwaneckeanum Hampe may be collected in the country in the future). This complex is characterized by linear-lanceolate leaves gradually narrowed to a fine point. The basal marginal border of thin-walled cells is entire, and some tubercles are always present on the basal cells. There is a tendency for upper cells to be longer than broad, and the leaves are irregularly twisted-contorted (never inrolled-crisped). Because of variability in this group, numerous taxa have been unnecessarily described. In M . cirrosum, the perichaetial leaves and areolation of the vegetative leaves are variable, and I cannot consistently recognize either var. stenophyllum (Mitt.) Grout or var. jamaicense (Mitt.) Grout. I cannot distinguish with certainty, by gametophytic features, M . cirrosum from M . longifolium; however, the latter tends to have longer, more undulate leaves and strongly 8-ribbed capsules and rough, thick setae. (Macromitrium schwaneckeanum seems quite distinct from M. cirrosum because of shiny leaves with upper cells longer than broad, rectangular, irregularly thick-walled, and in distinct, ridged rows.)

Most specimens have non-undulate leaves with slender apices and costa ending just below the apex, as well as tan-colored, smooth capsules. The areolation ofthe leaves in the Mexican populations seems to be fairly consistent, with rounded, almost smooth upper cells and tuberculate basal cells, particularly toward the costa. However, there is some puzzling intergradation. The leaf tips can be extremely long and slender but seem to intergrade with the "normal" condition. Strongly ribbed capsules resemble those of M. longifolium. I consider populations with 8-ribbed capsules and smooth setae M. cirrosum. I have seen a mixed collection of M. cirrosum and M. longifolium, and the two species showed no morphological intergradation.

Considering the numerous taxa that have been described in the complex and the variability of the characters, further observation over the entire range needs to be made. As far as Mexican specimens are concerned, recognizing two species seems satisfactory.

Distribution

On branches and trunks of trees, rarely on rock, seemingly common on fallen branches, perhaps indicating a habitat in the forest canopy; Chiapas, Hidalgo, Oaxaca, Puebla, Tamaulipas, Veracruz.—Mexico; Guatemala; northern South America; West Indies

Mexico North America| Guatemala Central America| Colombia South America| Brazil South America| Ecuador South America| Guyana South America| French Guiana South America| Peru South America| Venezuela South America| West Indies|