Abstract: Palaua (Malveae, Malvaceae) comprises 15 species endemic to the hyperarid coastal desert of Chile and Peru. So far, chromosome counts have been known for two diploid species (2n = 2x = 10) only. Here we report new chromosome numbers for 12 species of Palaua and four of its sister group Fuertesimalva. Karyotypes including DAPI/CMA₃ fluorescent banding are presented for selected species representative of each of the main clades of Palaua. An important finding is the discovery of polyploids in one exclusively tetraploid species (P. trisepala) and four species with mixed diploid and tetraploid cytotypes (P. dissecta, P. mollendoensis, P. moschata, P. tomentosa). The diploid and tetraploid karyotypes are all unimodal, symmetrical and show one or two pairs of satellite chromosomes with their associated CMA⁺/DAPI^- band depending on the cytotype. For some of the tetraploids an autopolyploid origin is suggested.

Key words: autopolyploidy, chromosome base number, desert, fluorochrome staining, lomas, Malveae, Urocarpidium.