“…From a karyological point of view, several authors have studied the genus, but chromosome numbers are known for only 28% of the taxa so far described, mainly for those from Asia and Africa (Chennaveeraiah & Patil, 1973; Gupta & Gupta, 1978; Raina & Verma, 1979; Verma, Kesavacharyulu & Raina, 1982, 1984; Verma & Raina, 1983; Husaini & Iwo, 1992). Among American species, the karyotypes for some Mexican (Palomino & Vázquez, 1991) and Brazilian populations (Cotias de Oliveira & Aguiar‐Perecin, 1999) have been described, in addition to a few chromosome numbers reported for populations in the United States (Windler, 1974), Colombia (Shibata, 1962) and Argentina (Fernández, 1977; Bernardello, Stiefkens & Piovano, 1990).…”