New chromosome numbers in 'Homoranthus' (Myrtaceae: Chamelaucieae) and notes on their taxonomic utility

Diploid chromosome counts are reported for the first time for 23 species of 'Homoranthus' (Myrtaceae) and published counts are confirmed for a further three species. H. 'wilhelmii' (F.Muell.) Cheel was determined as having 2n = 14, which contrasts with an earlier report of n = 6 for the species. Dysploidy appears to be common within the genus, with diploid chromosome numbers of 2n = 14, 16, 18 and 20 being recorded. There was no evidence of recent polyploidy within 'Homoranthus' nor of any infraspecific dysploidy. Chromosome numbers appear to be a useful taxonomic tool to confirm the distinctness of some morphologically similar taxa but may be of limited use in estimating phylogenetic relationships.