Cyrto-hypnum involvens (Hedw.) W.R.Buck & H.A.Crum

Authority

Buck, William R. 1998. Pleurocarpous mosses of the West Indies. Mem. New York Bot. Gard. 82: 1-400.

Family

Thuidiaceae

Scientific Name

Cyrto-hypnum involvens (Hedw.) W.R.Buck & H.A.Crum

Description

Species Description - Plants small and slender, in typically stiff, dull, mostly dark-green (becoming golden with death), often dense mats. Stems creeping, to ca. 3 cm long, 1-pinnate, not frondose; in cross-section with 3-5 rows of small thick-walled cells surrounding larger thinner-walled cells, central strand small, of small cells; paraphyllia usually very sparse on stems, absent on branches, filamentous, 1(-2)-seriate, unbranched, to ca. 8 cells long, the cells quadrate, ca. 1:1, all cells sparingly pluripapillose, the distal cell truncate; pseudoparaphyllia foliose, the margins irregularly serrulate, cells pluripapillose; axillary hairs usually with a single short-rectangular brown basal cell and a single elongate hyaline distal cell. Stem and branch leaves scarcely differentiated, stem leaves flexuosely incurved when dry, spreading when moist, ovate-triangular, (0.3-)0.5-0.6 mm long, ± abruptly short-acuminate, concave, not plicate, not decurrent; margins crenulate-papillose throughout, plane or narrowly recurved below; costa single, strong, disappearing in the acumen but not filling it, not projecting at apex; cells ± quadrate, obscurely pluripapillose on both surfaces, the papillae arranged around the periphery of the lumina, thin-walled, scarcely differentiated in the acumen or toward the insertion; alar cells not differentiated. Branch leaves strongly incurved when dry, spreading when moist, ± 2-ranked, often laxly disposed, oblong to oblong-ovate, ca. 0.5 mm long, obtuse to acute, concave, not plicate, not decurrent; margins regularly crenulate-serrulate, plane or narrowly recurved below; costa single, ending ca. 7/8 the leaf length, often ± flexuose, apex projecting at back as a small spine; cells ± quadrate, pluripapillose with (1-)2-4(-5) papillae/cell on both surfaces, the papillae arranged around the periphery of the lumina, thin-walled, ca. 8-9 µm wide, the apical cell usually crowned with 2-4 papillae; alar cells not differentiated. Asexual propagula none. Autoicous. Perichaetia conspicuous; leaves erect, lanceolate, to ca. 1.4 mm long, gradually long-acuminate; margins laxly serrulate above, subentire below or with a few coarse, blunt teeth, not ciliate, plane; costa single, extending into and filling the acumen; cells rectangular, smooth, firm-walled, those at basal margins usually shorter and thinner-walled. Setae elongate, slender, roughened throughout, orange, 0.8-1.5 cm long; capsules inclined to subpendent, broadly short-cylindric, 1-1.3 mm long; exothecial cells short-rectangular, firm-walled, ± wavy-walled; annulus not seen; operculum obliquely long-rostrate; exostome teeth yellow to yellow-brown, shouldered, bordered, on the front surface cross-striolate below, becoming papillose and then coarsely papillose above, trabeculate at back; endostome mostly with a high, smooth basal membrane, segments finely papillose, keeled, not or narrowly perforate, ca. as long as the teeth, cilia finely papillose, single or rarely with a rudimentary second one. Spores spherical, finely papillose, 11-14 µm diam. Calyptrae cucullate, naked, smooth.

Discussion

2. Cyrto-hypnum involvens (Hedw.) W. R. Buck & H. A. Crum, Contr. Univ. Michigan Herb. 17: 66. 1990; Leskea involvens Hedw., Sp. Musc. Frond. 218. 1801; Hypnum involvens (Hedw.) R Beauv., Prodr. Aethéogam. 65. 1805; Thuidium involvens (Hedw.) Mitt., J. Linn. Soc., Bot. 12: 575. 1869. Plate 75, figures 1-11 Discussion. Cyrto-hypnum involvens is distinguished by once-pinnate stems with the branch leaves strongly incurved when dry. The seta is rough and the perichaetial leaves are eciliate, as in T. scabrosulum, but in that species the plants are regularly twice-pinnate and the branch leaves are ovate rather than oblong. Also of note in C. involvens is the poor differentiation of branch and stem leaves. Thuidium was reported by Ireland (1971) not to have pseudoparaphyllia, and indeed, in Thuiclium s.str. it can he difficult to distinguish them from paraphyllia. However, in Cyrto-hypnum—and in C. involvcns in particular, where paraphyllia are so sparse—it is easy to see that the foliose structures around the bases of the numerous branches are not heteromorphous paraphyllia, but rather pseudoparaphyllia. A single, poorly preserved specimen from Jamaica (Webster s.n., NY, hb. Mitt.) is tentatively assigned here. The leaf cells are unipapillose and the seta is completely smooth, characters that should exclude it from C. involvens. However, for its once-pinnate habit and weak stem/branch leaf differentiation it is most comfortably placed here, and there is no other described taxon to which it is assignable. The plants are too scrappy to describe as new.

Distribution

Range. Florida, Mexico to northern South America; Bahamas (Grand Bahama), Cuba, Jamaica, Hispaniola (Haiti and Dominican Republic), Mona Island, Puerto Rico, Virgin Islands (St. Thomas), St. Martin, Guadeloupe;

Mexico North America| Central America| Bahamas South America| United States of America North America| Brazil South America| Colombia South America| Ecuador South America| French Guiana South America| Guyana South America| Peru South America| Suriname South America| Venezuela South America| Cuba South America| Jamaica South America| Dominican Republic South America| Haiti South America| Puerto Rico South America| Virgin Islands South America| Saint Martin South America| Guadeloupe South America|