Sematophyllum maguireorum W.R.Buck
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Authority
Buck, William R. 1990. Contributions to the moss flora of Guyana. Mem. New York Bot. Gard. 64: 184-196.
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Family
Sematophyllaceae
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Scientific Name
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Description
Latin Diagnosis - Folia ovato-lingulata late acuta vel rotundata 0.85-1.1 X 0.45-0.5 mm; setae ca. 4 mm longae; capsula erecta ca. 1 mm longa; cellulae exothecu infirme collenchymatae; dentes exostomii acuminati ad basem transverse striolati ad apicem papillosi; endostomii membrana basalis humilis segmenta linearia papillosa dentibus breviora.
Species Description - Plants dull green to yellow-green in dense mats. Stems creeping, irregularly branched. Leaves crowded, ± contorted when dry, erect and strongly concave when moist, ovate-lingulate, 0.85-1.1 mm long, 0.45-0.5 mm wide, broadly acute to rounded; margins plane or narrowly recurved below, subentire throughout; ecostate; cells rhomboidal to hexagonal above, 1.5-2(-3): 1, thin- to firm-walled, becoming long-hexagonal at midleaf, ca. 5-6:1, and more elongate, thickwalled and porose toward the orange insertion; alar cells orange, enlarged and ± inflated in a single row with 3-5 rows of supraalar cells in a triangular area extending up the margin. Autoicous. Perichaetial leaves erect, oblong-ovate, ca. 1.4 mm long, acute, with margins serrulate above. Setae somewhat flexuose, orange, ca. 4 mm long, smooth; capsules erect, cylindric, ca. 1 mm long, contracted below the mouth when dry, symmetric; exothecial cells slightly coUenchymatous, the cross-walls thinner than the vertical ones; annulus none; operculum straight to suboblique, short-rostrate; peristome inserted below the mouth of the urn, exostome teeth lanceolate-acuminate, on front surface cross-striolate with overlying papillae in lower 1/4, finely papillosespiculose above, slightly trabeculate at back; endostome with a very low basal membrane, barely reaching the mouth of the urn , segments linear, papillose, not keeled, not perforate, shorter than the teeth, cilia none. Spores spherical, 14-21 µm in diameter, finely roughened. Calyptrae cucullate, smooth, naked.
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Discussion
Type. BRAZIL. Amazonas: Rio Cauaburi, Base C a m p in Cano Tucano (3rd Serra da Neblina Expedition), 125 m , 11 N o v 1965, Bassett M a guire, Julian A. Steyermark & Celia K. M a guire 60142 (holotype N Y ) . Paratypes. B R A ZIL. Roraima: K m 349 along B R 174 (Manaus-Venezuela Hwy), in and along Rio Branquinho, 7 k m S of Equator, ca. 150 m , 19 Nov 1977, W.R. Buck etal. 7552 (INPA, N Y ). G U Y A N A . Basin of Kuyuwini River (Essequibo tributary), about 150 miles from mouth, 21-26 Nov 1937, A. C. Smith 2565 (NY, U)
All collections were made on logs or dead branches along rivers, probably susceptible to periodic inundation. Sematophyllum maguireorum is gametophytically indistinguishable from several other semiaquatic Sematophyllaceae, all with broadly ovate to rounded leaves with short apical cells. H o w ever, it is immediately recognizable by the peristome inserted below the mouth and the very reduced endostome. I know of no other species of Sematophyllum with inserted peristomes although the phenomenon is c o m m o n among epiphytic Hypnales. Similarly, the epiphytic habitat seems to drive the endostomial reduction. Another collection at N Y of unknown country (ad ostia Combasa, Spruce 118) has an identical peristome but more acute leaf apices and probably also represents this species.