Chromosome number and satellited chromosome morphology of eleven species of <i>Arachis</i> (Leguminosae)

Abstract

The chromosome number was determined in eleven recently-described species of Arachís belonging to five different axonomic sections.  Two new species  of section  Arachís, A. Gregoryí and A. Krapovíckasíí, present 2n520 chromosomes and lack the small ‘A’ pair, while A. línearífolía and A. Schíníníí have 2n520, including the small ‘A’ pair of chromosomes, typical of the A genome of A. hypogaea. Arachís Schíníníí, previously listed under A. Hoehneí, a species  lacking  this pair of chromosomes, has many morphological differences, and is therefore considered to be a new species. Arachís submargínata (sect. Extranervosae), A. Pflugeae and A. Hasslerí (sect. Procumbentes), and A. serídoénsís and A. ínterrupta (sect.  Heteranthae) also have 2n520.  One species  of section Rhízomatosae, A. nítída, is tetraploid (2n540), but is morphologically distinct from the other tetraploids in this section. The new species of section Erectoídes, A. porphyrocalyx, shows 2n518. This is the first count of 2n518 chromosomes for an Arachís species outside section Arachís and its origin is probably not associated with the origin of the 18 chromosomes occurring in three species of section Arachís