A morphometric analysis of the Banksia spinulosa complex (Proteaceae) and its complex taxonomic implications

Abstract

Specimens of all known taxa and putative entities belonging to the Banksia spinulosa complex were collected from Kuranda in northern Queensland, western to central Queensland and down the eastern coast of Australia to Wilsons Promontory in southern Victoria. These specimens were used to investigate morphological variation in habit, stems, leaves, inflorescences, fruits and seeds in the complex. Phenetic analysis (unweighted pair-group method with arithmetic mean, UPGMA, clustering and semi-strong hybrid multi-dimensional scaling, SSH–MDS, ordination) was performed on the full dataset of 233 entities using 33 characters (18 quantitative, two binary and 13 multistate). To facilitate visualisation of patterns in both clustering and ordination, we also analysed subgroups based on the results of the phenogram from the full dataset. The results showed that the five known and described taxa are phenetically distinct, viz. B. collina sens. str., B. cunninghamii sens. str., B. neoanglica, B. spinulosa and B. vincentia, and provided support for a further 12 morphometrically diagnosable entities, four of which could not be diagnosed with simple combinations of character states and require further investigation. The present study has highlighted that there is much more hidden morphological diversity in the B. spinulosa complex than has previously been recognised in any of the current competing taxonomies.