Morphometric study of Euchiton (Gnaphalieae: Asteraceae)

Abstract

A morphometric study was undertaken to survey taxa in the genus Euchiton Cass., distributed across Australia, New Zealand and South-east Asia. Phenetic analyses of herbarium specimens showed several taxa to be well delimited, including E. brassii (Mattf.) Anderb., E. breviscapus (Mattf.) Anderb., E. lateralis (C.J.Webb) Breitw. & J.M.Ward, E. limosus (D.G.Drury) Holub, E. litticola A.M.Buchanan, E. traversii (Hook.f.) Holub and E. umbricola (J.H.Willis) Anderb. However, the analyses showed that the remainder of Euchiton taxa are not yet satisfactorily resolved taxonomically. The distributions of E. involucratus (G.Forst.) Holub and E. sphaericus (Willd.) Holub were elucidated, although these widespread species would benefit from more research. Further research is necessary into species delimitation between E. paludosus (Petrie) Holub and E. polylepis (D.G.Drury) Breitw. & J.M.Ward and within the E. japonicus complex, including E. audax (D.G.Drury) Holub, E. collinus Cass., E. delicatus (D.G.Drury) Holub, E. ensifer (D.G.Drury) Holub, E. japonicus (Thunb.) Holub and E. ruahinicus (D.G.Drury) Breitw. & J.M.Ward. Recognition of a proposed taxon E. ‘gracilis’ was not supported and description at this point is not recommended. The New Zealand material of E. audax, E. delicatus and E. ensifer was shown to differ from the Australian material in the micromorphology of the cypselae. Euchiton collinus is considered a synonym of E. japonicus, which also includes the Australian material attributed to E. audax, E. delicatus and E. ensifer. The presence of E. limosus in Australia was confirmed, with it differing from E. involucratus in having glabrous cypselae with paired papillae in both Australian and New Zealand material. Generic boundaries of Euchiton are problematic. The generic placement of Gnaphalium clemensiae Mattf. and E. umbricola remains unresolved. Insufficient data were available to make taxonomic conclusions regarding the generic placement of G. chiliastrum (Mattf.) P.Royen and G. heleios P.Royen from New Guinea.