New records in the genus Carex L . ( Cyperaceae ) for Brazil and Rio Grande do Sul

Carex brongniartii Kunth is a new record for Brazil and C. seticulmis Boeck. for the state of Rio Grande do Sul, Brazil. Morphological data for the identification of the two species, including short descriptions and illustrations are provided, as well as data on habitat and distribution.


Introduction
Carex L. is the genus of Cyperaceae with the largest number of species, about 2000 according to Goetghebeur (1998).Although its main centres of diversity are in North America and East Africa (Starr et al. 1999), it is well represented in South America, with about 200 species (Wheeler 2002), especially in highlands.
There are still no estimates published for Brazil; however, 18 species were listed by Guaglianone et al. (2008) for the Southern Region.Preliminary data for Rio Grande do Sul indicate the occurrence of 17 species, included in the subgenera Carex, Primocarex Kuk., and Vignea (P.Beauv.Lestib ex.f.) Peterm.
This paper presents two new records of species of Carex, one for Brazil and one for the state of Rio Grande do Sul; it also provides means for their identifi cation and data on their distribution and habitat.

Material and methods
This work is based on revision of literature, field collections (specimens deposited in the ICN herbarium) and revision of the following herbaria: BLA, SH, ICN, MPUC, PACA, SMDB and PEL (Holmgren & Holmgren 1998).

Results and discussion
Carex includes herbaceous, rhizomatous and perennial species, monoecious, rarely dioecious, with spikelets grouped in a spike.The presence of an adaxial ligule, uncommon in the genera of Cyperaceae, is an important recognition characteristic, as well as the presence of the perigynium, a membranous envelope covering the achene.
One of the new submitted records, Carex brongniartii, is included in Carex subg.Vignea, while C. seticulmis is included in the subgenus Primocarex.In addition, the subgenus Carex is also represented in Rio Grande do Sul.
The species of Primocarex have three stigmas and only one bisexual spike at the apex of the scape.The species of the other two subgenera present two stigmas, with bisexual and androgynous spikes (several pistillate spikelets at the base and a few staminate at the apex) in Vignea, and unisexual spikes (one or several staminate apical spikes preceded by 4-5(-8) pistillate spikes) in species of the subgenus Carex.
Distribution and habitat: widely distributed in Southern South America, cited by Guaglianone et al. (2008) for Argentina, Chile and Uruguay.The present work is its fi rst citation for Brazil.Seldom found in Rio Grande do Sul, occurring in the Pampa Biome, in swamps and wet areas of the Southeast and Southwest of the state and in "restingas" (areas with sandy, acidic, and nutrient-poor soils) in the South coast.Carex brongniartii is characterized mainly by the ventral part of the leaf sheath being more delicate than the remainder, conspicuously hyaline, continued in the apex by a contraligule acute (Fig. 2), and by the lower involucral bract setaceous, usually not exceeding the length of the infl orescence.Other important features for the recognition of this species are the presence of nerves at the base of the perigynium, on both faces (Fig. 4).
Carex sororia Kunth, another species of the subgenus Vignea in Rio Grande do Sul, has the shape of the infl orescence and the perigynium similar to C. brongniartii.It differs from the latter by the leaf sheath being of equal consistency throughout, without a hyaline ventral part, by the obtuse contraligule and also by the foliaceous lower involucral bract, (5-)7-14 cm long and 1-5 mm wide, two to six times longer than the infl orescence.In addition, C. sororia presents nerves only in one face of the perigynium, being one of the most common species of Carex in Rio Grande do Sul, occurring in disturbed habitats.