Rhynchostegium scariosum (Taylor) A.Jaeger
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Authority
Buck, William R. 1998. Pleurocarpous mosses of the West Indies. Mem. New York Bot. Gard. 82: 1-400.
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Family
Brachytheciaceae
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Scientific Name
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Description
Species Description - Plants relatively slender, in often dull, soft, yellow-green, dense mats. Stems creeping, subpinnately branched, the branches short; in cross-section with 1-3 rows of small thick-walled cells surrounding larger thin-walled cells, central strand small but distinct, of small thin-walled cells; pseudoparaphyllia foliose; axillary hairs with a single short brown basal cell and (2-)3(-4) elongate brown roughened distal cells. Stem and branch leaves slightly differentiated with the stem leaves having a somewhat broader insertion and sometimes ± falcate, otherwise ± distant and not or only somewhat overlapping, obscurely complanate and contorted when dry, neither complanate nor contorted when moist, erect- to wide-spreading, lanceolate, 0.85-1.5 mm long, gradually acuminate, the apex sometimes with a single twist; margins serrate to serrulate throughout, plane or rarely suberect, sometimes narrowly recurved at base; costa single, fairly prominent, tapering distally, ending at ca. 3/4 the leaf length, usually projecting as a small spine; cells linear, straight to subflexuose, smooth, thin- to firm-walled, not porose, not becoming shorter in the acumen; alar cells gradually but distinctly differentiated, often in concave areas, quadrate to short-rectangular, not or sometimes reaching the costa, extending up the margins in ca. 5 rows. Asexual propagula none. Autoicous. Perichaetia inconspicuous; leaves wide-spreading from an erect base, oblong-lanceolate, 1.2-1.5 mm long, ± gradually to abruptly slenderly long-acuminate; margins serrulate above, subentire below, plane; costa single and ending 1/4-1/3 the leaf length, or none; cells linear, smooth, firm- to thick-walled, ± porose, becoming shorter, broader, and thinner-walled toward the insertion; alar cells not differentiated. Setae elongate, smooth, reddish, 1.3-1.5 cm long, ± straight except usually curved just below urn, twisted; capsules inclined to horizontal, not strikingly arcuate, ± asymmetric to symmetric, cylindric, 1-1.3 mm long, constricted below the mouth when dry and empty; exothecial cells subquadrate to short-rectangular, thin- to firm-walled; annulus of 1-2(-3) rows of short-rectangular to elongate, thick-walled cells, the shorter ones similar to those of the exothecium; operculum obliquely long-rostrate; exostome teeth reddish brown, triangular, obscurely shouldered, narrowly bordered, on the front surface cross-striolate below, coarsely papillose above, trabeculate at back; endostome with a high, ± smooth basal membrane, segments papillose, keeled, broadly perforate, becoming gaping, somewhat shorter than the teeth, cilia usually in pairs, nodulose, shorter than the segments. Spores spherical, finely papillose, ca. 11-12 µm diam. Calyptrae cucullate, naked, smooth.
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Discussion
3. Rhynchostegium scariosum (Taylor) A. Jaeger, Ber. Thatigk. St. Gallischen Naturwiss. Ges. 1876-77: 374. 1878; Hypnum scariosum Taylor, London J. Bot. 5: 65. 1846; Eurhynchiella scariosa (Taylor) R. S. Williams, Bryologist 31: 113. 1928; Steerecleus scariosus (Taylor) H. Rob., Mem. New York Bot. Gard. 45: 681. 1987. Plate 98, figures 8-15 Rhynchostegium argute-serratum E. B. Bartram, J. Wash. Acad. Sci. 26: 13. 1936; Steerecleus argute-serratus (E. B. Bartram) H. Rob., Mem. New York Bot. Gard. 45: 680. 1987. Discussion. Rhynchostegium scariosum is characterized by its relatively slender plants, which at times resemble a Mittenothamnium. It has lanceolate leaves that are somewhat twisted and contorted when dry. The alar cells are relatively numerous for a Rhynchostegium. In aspect it somewhat resembles R. callistomum Besch. of Mexico but differs from that species in the narrower leaves. It differs most conspicuously from R. serrulatum in the noncomplanate-foliate habit, especially when moist. The name R. arguteserratum is nothing more than a regional name for this widespread American species.
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Distribution
Range. Mexico, Guatemala, northern Andean South America; Cuba, Jamaica, Hispaniola (Haiti and Dominican Republic), Puerto Rico; often growing on old wood, or sometimes over rock, in mesic to humid forests, usually above 1000 m.
Mexico North America| Guatemala Central America| Peru South America| Ecuador South America| Colombia South America| Venezuela South America| Cuba South America| Jamaica South America| Dominican Republic South America| Puerto Rico South America|