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

Abstract

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.

Progress in Myrtaceae genetics and genomics: Eucalyptus as the pivotal genus

“…Chromosome counts for 150 Western Australian species of the Myrtaceae, confirmed the base chromosome number of n011 but also revealed rare diploid variations as low as n05 (Rye 1979). Such variations were later confirmed by reports of 2n014, 16, 18, and 20 for species of Homoranthus (Copeland et al 2008). Occasional polyploids (2n 044) were reported in genus Leptospermum in New Zealand (Dawson 1987), although polyploidy is now generally considered rare in capsularfruited taxa.…”