Sphagnum squarrosum Crome , subgenus Squarrosa ( Russow ) Schimp . ( Bryophyta : Sphagnaceae ) , in South America

During a taxonomic review of Sphagnaceae of Brazil, I found 5 collections in herbaria of Sphagnum squarrosum, an interesting species because of its typically robust form with strongly squarrose branch leaves that give this species a “spiky” look. These are the first records of this species from Brazil and the first of the subgenus Squarrosa from South America. These 5 records represent the southernmost known populations of this species in the Southern Hemisphere. A brief description, a key to the species of subgenus Squarrosa, and illustrations are given.


Introduction
The family Sphagnaceae has a wide world distribution and includes 1 genus, Sphagnum L. with about 300 species in 6 monophyletic subgenera.In the Neotropics this family shows greatest diversity, with 6 subgenera represented and about 16 species (Gradstein et al. 2001, Shaw et al. 2010).Tropical America is one of the richest regions of the world for Sphagnum diversity, and much of this diversity is in southeastern Brazil and the tropical Andes (Gradstein et al. 2001).In Brazil, where 81 species occur, the genus predominates in the coastal Atlantic Forest region that extends from the northeast to south of the country (Costa 2015).Until now, the subgenus Squarrosa (Russow) Schimp.was not known from Brazil or South America.In my study of the family Sphagnaceae in Brazil I found 5 collections of Sphagnum squarrosum Crome from São Paulo and Rio Grande do Sul states.This is a species previously known from Europe, China, Japan, India, Korea, Siberia, New Zealand, Mexico, USA (including Alaska), and Greenland (Crum 1984, Crum andAnderson 1981).Here I provide a brief description and figures of S. squarrosum and a key to the species of the subgenus Squarrosa.

Methods
While studying herbaria records of the family Sphagnaceae from Brazil (part of the project "Synopsis of the Sphagnaceae to Brazil"), 5 collections were identified as S. squarrosum Crome (1803: 24-25) from southeastern and southern Brazil (see below).
The specimens were photographed in the laboratory and are housed in the herbaria ICN, MBM, PACA, and SP (Thiers 2015).Terminology for morphological structures follows Crum and Anderson (1991).The map was made using ArcMap 9.3.

Results
The identification was performed by consulting specialized bibliography (Crum 1980, Crum 1984, Crum and Anderson 1981).
Sphagnum squarrosum is a relatively robust plant, growing in loose pale-to yellow-green carpets; with terminal bud large; and cortical cells of stem without fibrils or pores.Stem leaves shorter than branch leaves, slightly concave, large (1.6-1.8 mm long), ovate-lingulate to oblong-lingulate, finely fringed at a rounded apex, bordered or not; leucocysts undivided and without fibrils.
Branches long and tapering with squarrose spreading leaves.Branch fascicle with 4 or 5, 2 spreading and 2 or 3 pendent.Cortical cells in 1 or 2 layers.Branch leaves larger than stem leaves (1.9-3.0 mm long), strongly squarrose, giving its "spiky" look, broadened at base and abruptly contracted at middle to an involute-concave apex, curved away from the branch, bordered by 1-3 rows of linear cells, distinctively curved away from the branch, leucocysts slightly convex on both surfaces, on the inner surface with 1-3 rounded to elliptic pores at ends and non-ringed pores on the outer surface, walls smooth or slightly papillose.In cross section, leucocysts concave on both surfaces, chlorocysts triangular or trapezoidal, equally exposed on both surfaces or more exposed on the outer surface (Figs 1, 2).
Sphagnum squarrosum is unmistakable because has a typical robust form with strongly squarrose branch leaves giving to this species a "spiky" look, growing in loose, pale green to yellowish carpets.Is a circumboreal taxon, widespread throughout the Northern Hemisphere from the sub-arctic to the warm temperate zones of Europe, Asia and North America and the new records reported here fit a disjunction pattern of distribution for this taxon, because the species of this subgenera are typically widespread on temperate zones.

Figure 1 .
Figure 1.Sphagnum squarrosum Crome. A. Habit.B. Fascicle.C, D. Stem leaves.E, F. Branch leaves.G. Upper cells of branch leaf, outer surface.H. Upper cells of branch leaf, inner surface.I. Branch leaf in cross sections.J. Portion of branch in cross section.K. Portion of stem in cross section (A.Sehnem 334).Illustrations by Maria Alice de Rezende.

Figure 2 .
Figure 2. Sphagnum squarrosum Crome. A. Habit.B. Detail of terminal bud.C. Fascicle.D. Detail of the branch leaves.E, F. Branch leaves.G, H. Stem leaves.I. Marginal cells of branch leaf.J. Median cells of branch leaf, inner surface.K. Branch leaf in cross section (A Sehnem 334).Photos by Denise Costa.

Figure 3 .
Figure 3. Map of Brazil showing the distribution of Sphagnum squarrosum.Solid black circles: new records.SP = São Paulo State, PR = Paraná State, SC = Santa Catarina State, RS = Rio Grande do Sul State (source: Center for Scientific Computing/JBRJ).