Sphagnum (section Sphagnum) tabuleirense sp. nov. is described from the State of Paraiba, northern Brazil. It is distinguished from other species of the section by single branches, stem and branch leaves bordered by a resorption furrow and having a similar porosity, and green cells of branch leaves somewhat more broadly exposed on the inner surface. Sphagnum is widely distributed over a vast area in Brazil, in wetlands along streams, at the margins of lakes, and also in wet, rocky, upland habitats. Many species have been described from southern Brazil (Warnstorf 1911), but those of northern Brazil are little known. The plants described here as a new species were found in coastal lowlands on a tabuleiro, or low plateau, in the state of Paraiba, in the municipality of Santa Rita, at 7?08'40S, 54002W. (Santa Rita is bounded by the municipalities of Sap6, Pedras de Fogo, Cruz do Espirito Santo, Mamanguape, and Joao Pessoa.) SPHAGNUM (section Sphagnum) TABULEIRENSE sp. nov. (FIG. a-j) Plantae graciles, flavidae, laxe foliatae, in tegetibus laxis. Epidermis caulina stratis 2-3 composita, efibrillosa, 1-porosa. Folia caulina lingulata, apice late rotundata, sulco resorptio limbata, 2.3-3 mm longa; cellulae hyalinae fibrillosae, poris et pseudoporis ut in foliis ramulinis. Rami non fasciculati; cellulae epidermidis fibrillosae, 1-2-porosae. Folia ramulina ovata, cucullato-concava, sulco resorptio limbata, 3-4 mm longa; cellulae hyalinae exteriore superficie pseudoporis magnis binis ternisque in cellularum angulis, etiam apice et marginibus foliorum poris paucis et parvis, interiore superficie 0-2 pseudoporis parvis; cellulae chlorophylliferae sectione transversali trapezoideae, cum pariete aliquantulum longiore superficie interiore sitae. Slender, yellowish, laxly foliate plants in loose, aquatic mats. Cortical cells of stems in 2-3 layers, efibrillose, 1-porose; wood cylinder orange-red. Stem leaves lingulate, broadly rounded at apex, bordered by a resorption furrow, 2.3-3 mm long; hyaline cells fibrillose throughout, with pores and pseudopores much as in branch leaves. Branches widely spaced, single or occasionally paired; cells of branch cortex fi rillose, 1-2-porose. Branch leaves ovate, cucullate-concave, bordered by a resorption furrow, 3-4 mm long; hyaline cells on outer surface with large, ringed pseudopores at adjacent angles and toward margins and apex, actual pores at corners and occasionally also at commissures, on the inner surface with 0-2 rather small, ringed pseudopores at angles and commissures; green cells trapezoidal, exposed somewhat more broadly on inner surface, hyaline cells convex on both surfaces but more so on outer surface. BRAZIL. PARAiBA: Municipio de Santa Rita, Tabuleiro de Santa Rita, dentro do riacho em tabuleiro, 22-V-1985, L. Xavier F lho, s.n. (holotype, sp 231902; isotype, MICH). This aquatic species is especially interesting because of single (or rarely paired) branches. The cells of the stem cortex lack fibrils, but those of the branch cortex are spirally fibrillose. The stem leaves resemble the branch leaves in the number and distribution of pores and pseudopores and also in having a marginal resorption furrow. The green cells of branch leaves are trapezoidal in transverse section and somewhat more broadly exposed on the inner surface. Sphagnum longistolo C. Miill. ex Warnst. also has nonfasciculate branches, but its green cells are central and entirely included.