SPOROBOLUS INDICUS (L.) R. BR. (GRAMINEAE), A NEW ADVENTIVE SPECIES IN THE FLORA OF SERBIA

During field studies of semi-saline meadows and marshes carried out along the Ponjavica River in the vicinity of Banatski Brestovac (Vojvodina, Serbia), we found several specimens of Sporobolus indicus (L.) R. Br. The plant grows in transitional zones between disturbed damp mesotrophic grassland vegetation and semiaquatic communities belonging to the alliance Bolboschoenion maritimi continentale Soó. This adventive and potentially invasive species with a worldwide distribution has never before been recorded in Serbia.


INTRODUCTION
The genus Sporobolus R. Br. (subfam.Chloridoideae Rouy: tribe Zoysieae Miq.: subtribe Sporobolinae Bentham) includes almost 200 species distributed in tropical, subtropical and temperate regions of the world (Simon et al., 2011 onwards;Peterson et al., 1997).According to the recent cpDNA and nITS DNA sequences data, this is a polyphyletic genus with its center of diversity in tropical regions of the world (Peterson et al., 2010).The pantropical species complex of S. indicus (L.) R. Br. consists of numerous intergrading taxa with many intermediates which are sometimes recognized as varieties of S. indicus s.l.(Zhenlan and Phillipps, 2006).The only autochthonous representatives of the tribe Zoysieae in Serbia belong to the genus Crypsis Aiton (Cincović and Kojić, 1976a;1976b).
During our floristic investigation of semi-saline meadows and marshes along the Ponjavica River near Banatski Brestovac (Vojvodina) in 2012, we found a few specimens of Sporobolus indicus (L.) R. Br. (Map.1).A review of literature data indicates that this taxon had not yet been recorded in Serbia.

MATERIALS AND METHODS
Herbarium material is deposited in the Institute for Nature Conservation of Vojvodina province in Novi Sad (PZZP).The taxon description follows Hansen (1980), Rozhevits (1934) and Clayton et al. (2006 onwards), with some additional comments based on the specimen collected by the authors.Distribution data in Serbia are mapped on a 10 × 10 km UTM grid system (Lampinen, 2001).
Introduction pathways -High seed productivity, sticky gelatinous pericarp and late ripening greatly contribute to the potential dispersal of S. indicus by migrating birds and other animals that inhabit marshes and riverbanks (Walton, 2001).The significance of epizoochory and endozoochory in the longdistance transport of marsh plants is especially emphasized by some authors (Vivian-Smith and Stiles, 1994;Mueller and Van der Valk, 2002;Wongsriphuek et al., 2008;Brochet et al., 2009;2010;Figuerola et al., 2010).The Danube with its adjacent area (including the Ponjavica River) forms one of the most important bird migration corridors in Europe (Sommerwerk et al., 2009).The next (and another) record of S. indicus in the Danube valley is near Kolarovo in northeastern Bulgaria (Vălev, 1963).
Recent activities connected with the construction of a beach on the riverbank of Ponjavica involving the deposition of gravel, which may have contained the seeds of S. indicus, could be considered as a possible introduction pathway.