Systematics of the Australian species of Dictyopteris (Dictyotales, Phaeophyceae)

Abstract

Eleven species of Dictyopteris are recognised for Australia. The tropical species D. australis (Sonder) Askenasy, D. deliculata Lamouroux, D. plagiogramma (Montagne) Vickers, D. repens (Okamura) Børgesen, D. serrata (Areschoug) Hoyt and D. woodwardia (R.Brown ex Turner) C.Agardh are recorded for warmer coasts, although isolated populations of D. australis occur in the Gulfs region of South Australia. Dictyopteris acrostichoides (J.Agardh) Bornet and D. crassinervia (Zanardini) Schmidt are endemic to eastern Australia, with D. acrostichoides also extending to the eastern end of the southern coast. Dictyopteris gracilis Womersley and D. muelleri (Sonder) Reinbold occur on temperate southwestern and southern coasts. The west coast species Dictyopteris secundispiralis J.A.Phillips sp. nov. is described, and D. nigricans Womersley is reduced to a taxonomic synonym ofD. muelleri. Detailed comparative studies undertaken on these species have identified several new taxonomically-informative characters useful for generic circumscription and species discrimination. Thallus branches which have a cortical layer composed of large cuboidal cells and reproductive organs scattered in fertile zones are additional characters which characterise the genus. Australian species of Dictyopteris are now well defined by differences in several distinctive vegetative and reproductive characters such as thallus morphology, blade cell layer number, structure of the thallus apex, presence of marginal teeth and lateral veins, distribution and structure of hair bundles, sporangia, oogonia and antheridial sori.