IntroductionThe genus Lotus (Fabaceae; previously Leguminosae) comprises nearly 200 annual and perennial species that are distributed worldwide, except in very cold regions and in some tropical areas of Southeast Asia and Central America (Allan et al., 2004;Escaray et al., 2012). Within this genus, more than 15% of the species are endangered, vulnerable, or rare (IUCN, 2015). Several species are important forage crops (e.g., L. corniculatus, L. uliginosus, L. tenuis, and L. subbiflorus) since their nutritional value is similar or even superior to that of white clover and alfalfa (Jones and Earle, 1966;Escaray et al., 2012).Lotus taxonomy is one of the most problematic within the tribe Loteae due to the limited number of appropriate discernable morphological traits, insufficient genetic description, and high morphological and biogeographical diversity (Grant and Small, 1996;Allan et al., 2004;Escaray et al., 2012). Therefore, in addition to morphological analyses, karyological and molecular studies should be applied for species identification and establishing taxonomic assignment and phylogenetic relationships.The majority of Lotus species have the basic chromosome number x = 6 or 7 and are mostly diploids. However, in some species both diploid and tetraploid accessions occur, while others include only tetraploid forms (e.g., L. corniculatus;Ferreira and Pedrosa-Harand, 2014). Genome sizes of the genus Lotus have been reported for 39 species only (20%), with a range from 0.56 to 2.80 pg/2C (