Orthostichella hexasticha (Schwägr.) W.R.Buck

Authority

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

Family

Lembophyllaceae

Scientific Name

Orthostichella hexasticha (Schwägr.) W.R.Buck

Description

Species Description - Plants mostly relatively slender, sometimes medium-sized, in pendent, ± lustrous, pale-green or less often brownish green, usually dense colonies. Stems creeping to pendent, to ca. 35 cm long, but usually not much more than 15 cm, freely branched, in young material sometimes ± pinnate, the branches seemingly indeterminate and capable of becoming stems; in cross-section with 3-5 rows of small thick-walled cells surrounding larger firm-walled cells, central strand none; paraphyllia absent; pseudoparaphyllia broadly foliose, the apex broadly obtuse and bluntly toothed; axillary hairs with 1 (-2) short brown basal cells and (1-)2(-4) long-rectangular hyaline distal cells. Stem and branch leaves scarcely differentiated, conspicuously seriately ranked, the broadly oblong leaf base ± appressed to erect, the broadly obovate upper part of leaf abruptly flexed and spreading, sometimes subpanduriform, the overall shape resembling a spade from a deck of playing cards, ca. 0.6-1 mm long, the stem leaves to ca. 1.5 mm long, cuspidate, deeply concave above, ± cordate at base; margins serrulate almost throughout but occasionally subentire in the cusp, incurved above and sometimes below as well; costa short and double or none, rarely (and then usually in stem leaves) single and very short; cells long-hexagonal, ca. 10:1, to ca. 45 pm long, smooth, ± thick-walled, subporose, often becoming shorter near base of the cusp; alar cells gradually differentiated, few, subquadrate to short-rectangular, extending up the margins in (1-)2-4 (-5) rows and across the insertion by 4-6(-8) rows but not coming near to the costa, yellow across the entire insertion. Asexual propagula none. Dioicous. Perichaetia conspicuous, on branches; leaves differentiated, erect with spreading apices, greatly exceeded by vaginular hairs, oblong-lanceolate, 1.5-2 mm long, gradually short-acuminate; margins subentire, plane; costa none or obscure and single; cells linear, smooth, thick-walled, ± porose; alar cells not differentiated. Setae short, ± roughened just below the urn, yellowish, 2-3 mm long, curved; capsules exserted, erect, symmetric, broadly cylindric, 1.2-1.5 mm long; exothecial cells subquadrate to short-rectangular, thick-walled, becoming smaller and oblate toward the mouth; annulus of 1-2(-3) rows of small oblate to subquadrate thick-walled cells, fragmenting tardily; operculum obliquely rostrate; exostome teeth linear-triangular, pale, not or scarcely shouldered, not or narrowly bordered, on the front surface with basalmost plates irregularly cross-striolate, finely papillose above, not trabeculate at back; endostome with a low, finely papillose basal membrane, only extending 2-3 cells above capsule mouth, segments finely papillose, keeled, narrowly perforate, as long as or longer than the teeth, cilia rudimentary. Spores spherical, finely papillose, 14-20 µm diam. Calyptrae cucullate, naked or with a few erect hairs attached near base, roughened above.

Discussion

1. Orthostichella hexasticha (Schwagr.) W. R. Buck, Bryologist 97: 435. 1994; Hypnum hexastichum Schwagr., Sp. Musc. Frond. Suppl. 1(2): 210. 1816; lsothecium hexastichum (Schwagr.) Brid., Bryol. Univ. 2: 380. 1827; Pilotrichum hexastichum (Schwagr.) Müll. Hal., Bot. Zeitung (Berlin) 6: 767. 1848; Neckera hexasticha (Schwagr.) Müll. Hal., Syn. Musc. Frond. 2: 126. 1850; Meteorium hexastichum (Schwagr.) Mitt., J. Linn. Soc., Bot. 12: 432. 1869; Pilotrichella hexasticha (Schwagr.) A. Jaeger, Ber. Thätigk. St. Gallischen Naturwiss. Ges. 1875-76: 257. 1877. Plate 91, figures 1-8 Discussion. Orthostichella hexasticha is unique in its leaf shape, much resembling a spade in a deck of playing cards. The oblong base is ± appressed to the stem and the flared, deeply concave upper portion is abruptly flexed and spreading. It differs from our only other species in the genus, O. pentasticha, by the different leaf shape, thicker-walled laminal cells, smaller perichaetial leaves with exserted vaginular hairs, and shorter setae. Orthostichella hexasticha is very common in Hispaniola, and is the only species of the genus on that island. In Cuba it is restricted to the Sierra Maestra in the easternmost part of the island, and the Sierra Escambray of south-central Cuba. Reports from other islands and mainland localities all seem to be based on misdeterminations.

Distribution

Range. Cuba, Hispaniola (Haiti and Dominican Republic); growing on trees and shrubs, less often on rocks, in humid forests, at 1100-2000 m.

Cuba South America| Haiti South America| Dominican Republic South America|