Sphagnum aureum, a New Species from Costa Rica

Abstract

Sphagnum aureum sp. nov. (section Sphagnum) is reported from high elevation peatlands in Costa Rica. This species is similar to S. alegrense and S. magellanicum, but differs from these species in branch leaf, stem leaf, and cortical cell morphology. While collecting bryophytes in Costa Rica, I found specimens of Sphagnum that represent a new species in section Sphagnum of the genus. SPHAGNUM AUREUM McQueen, sp. nov. (FIG. 1-8) Plantae pallido-auricolores, pallido-fuscae. Cellulae epidermidis caulinae stratis 3, fibrosae, parietibus exterioris cellularum superficialium foraminibus 1-2(-3) instructis, apice porosis ellipticis. Folia caulina plana, late lingulata, 1.0-1.4 mm longa; cellulae hyalinae breves, non septatae, non fibrosae, aporosae. Rami 4 in fasciculo. Folia ramulina 1.0-1.5 mm longa, ovata, concava; cellulae hyalinae dorso poris magnis in clelularum angulis, interiore folii superficie aporosae; cellulae chlorophylliferae sectione transversali ellipticae, intercellulas hyalinas perfecte mediae, utrinque inclusae. Plants pale gold, tan, or light-brown. Stem cortical cells in 3 layers, fibrillose, outer cortical cells with 1-2 (sometimes 3) pores, apical pore commonly elliptical. Stem leaves flat, lingulate, 1.0-1.4 mm long; hyaline cells short, undivided, without pores or fibrils. Branches in fascicles of 4 (2 spreading, 2 pendent). Branch leaves 1.0-1.5 mm long, oblong-ovate, deeply concave; hyaline cells of outer surface with pores in groups of 3 at adjacent angles and with a few singly at sides, inner surface aporose or with only a few pores; chlorophyllous cells elliptic in cross section, central, entirely included, hyaline cells slightly convex on both surfaces, with smooth inner walls. TYPE: COSTA RICA. In wet seep near lower limit of piramo of north face of Cerro de la Muerte, 3,250 m, Cyrus B. McQueen 4020 (holotype, vT; isotype, CR). This species resembles S. alegrense Warnst. and S. magellanicum Brid., but differs from both in a number of features (Fig. 1-8): S. aureum is pale gold, tan, or pale brown, without any red coloration as in S. magellanicum and S. alegrense. The chlorophyllose cells of the branch leaves are similar to those of S. magellanicum. Sphagnum aureum and S. magellanicum differ from S. alegrense, in that they lack the vermiform ridges on the inner side walls (Allen 1986; Crum 1980, 1984). Sphagnum aureum also has fibrillose cortical cells as in S. magellanicum, whereas those of S. alegrense are efibrillose. Some other unique features of S. aureum are that on the inner surface the branch leaf hyaline cells are aporose or have only a few pores. The stem leaves of anisophyllous plants are about half the length of those of S. magellanicum. The pores of the cortical cells are also different from those of S. magellanicum and S. alegrense in that there are 2 pores (rarely 3) per cell and the upper pore of each cell is elliptic in shape. The anisophyllous plants of S. aureum that I collected were growing at the lower limit of the pairamo of Cerro de la Muerte. The plants formed small, tightly compact hummocks at the bases of stands of bamboo and small cushions on the edges of eroded stream banks. The pH of standing water around the S. aureum populations ranged from 3.95 to 4.95 (based on seven samples). Sporophytes were found on some plants in each of the small hummocks and cushions that I found. Other species growing in the type locality include S. alegrense, S. magellanicum, S. meridense (Hampe) C. Miill., S. sparsum Hampe, and S. perichaetiale Hampe.