The Rubiaceae tribe Psychotrieae sensu lato and its two largest genera, Psychotria L. and Palicourea Aubl., have been considered taxonomically controversial for a long time. We aimed to identify structural features of the ontogeny of the fruits and seeds with taxonomic potential for the tribe by using species of these two genera, and Rudgea jasminoides (Cham.) Müll.Arg. The samples were obtained from a herbarium and from Brazilian state parks, and sectioned by using a rotation microtome. The fruits were found to be derived from an inferior ovary, and were characterised by a fleshy mesocarp and sclerenchymatic sinuate pyrene. The seeds were pachychalazal and arillate. The fruit was classified as a pomaceous drupoid nuculanium. The investigation showed the utility of some fruit features to discriminate species. Our study also showed that ontogenetic features of fruits and seeds are very homogeneous in Palicourea and Psychotria, which supports the inclusion of both genera in the tribe Psychotrieae.

A recent molecular phylogeny of Amanita recognises three subgenera and 11 sections. Members of subgenus Amanitina are characterised by amyloid spores and a mycorrhizal habit. Section Arenariae falls within this subgenus. Members of this section are known only from southern Australia; they are either sequestrate (secotioid) or agaricoid and lack clamp connections. We describe the following three additional secotioid species: Amanita arenarioides Bougher, E.M.Davison & Giustiniano, A. compacta Bougher, E.M.Davison & Giustiniano and A. pseudoarenaria E.M.Davison, Giustiniano & Bougher, which are separated on macroscopic appearance, spore shape and genetic sequences. We also describe two agaricoid species, namely, A. pupatuju E.M.Davison, Giustiniano, McGurk & E.L.J.Watkin, and A sabulosa E.M.Davison & Giustiniano, which are separated on bulb shape and genetic sequences. We provide expanded descriptions of A. arenaria (O.K.Mill. & E.Horak) Justo and A. griselloides D.A.Reid; we also synonymise A. dumosorum D.A.Reid with A. peltigera D.A.Reid. A revised diagnosis and description of section Arenariae is provided, together with a key to currently recognised member of this section.

In the present study, we tested the chronological and geographic origins of the mostly arid Australian Ptilotus (Amaranthaceae) and its close relatives (i.e. the ‘aervoids’) by reconstructing a dated phylogeny with near-comprehensive sampling for Ptilotus and estimating ancestral geographic ranges. We investigated climatic niche evolution within Ptilotus and identified likely climatic origins and subsequent niche shifts by reconstructing ancestral states of climatic variables on the phylogeny, which was visualised using a phyloecospace approach. Geospatial analyses were employed to identify probable diversification hotspots within Australia. We inferred that the aervoids originated in Oligocene Africa–Asia and that Ptilotus arrived in northern Australia by dispersal in the Early Miocene. Subsequent diversification of Ptilotus was rapid, giving rise to all major clades in the western Eremaean by the time of an aridification pulse in the Middle Miocene. Climatic niche shifts from the arid Eremaean into monsoonal northern and temperate southern Australia are apparent for multiple independent species groups. Our analyses support the hypothesis that a pre-adaptation to aridity and early arrival in an aridifying Australia were integral to the success of Ptilotus, and that the Eremaean has been a source of biodiversity in the genus and for independent radiations into neighbouring climatic zones.

Defining species in the brown algal genus Colpomenia is a challenging endeavour because of their morphological similarity, overlapping phenotypic variation, the absence of conspicuous diagnostic characters, and often lack of reproductive structures crucial for their identification. Thus, the use of molecular tools has become widely used to study Colpomenia taxonomy and evolution. The following four Colpomenia species are described along the Australian coast: C. claytoniae M.Boo, K.M.Lee, G.Y.Cho & W.Nelson, C. ecuticulata M.J.Parsons, C. peregrina Sauvageau, and C. sinuosa (Mertens ex Roth) Derbès & Solier. The objective of this study was to assess the diversity of Colpomenia species in southern and south-eastern Australia by using DNA barcoding techniques and single-marker species delimitation methods. We generated 44 new COI-5P DNA sequences from nine different populations across three Australian states (South Australia, Victoria and Tasmania), and applied 13 variations of four species delimitation methods (ABDG, SPN, PTP, GMYC). Our results recognised three Colpomenia species in the region, namely, C. sinuosa, C. claytoniae, and C. peregrina. Colpomenia sinuosa is the most widely distributed species in Australia. Colpomenia peregrina and C. claytoniae presented high levels of intraspecific genetic divergence. We did not find C. ecuticulata, although it has been previously reported from nearby our sampling area.

In Acacia, 90% of species have drought-tolerant phyllodes as their adult foliage, the remaining species have bipinnate leaves. We conducted tests for relationships between foliage type and 35 bioclimatic variables at the continental scale and found significant correlations of both ‘moisture seasonality’ and ‘radiation in the coldest quarter’ with foliage type. Bipinnate species have lower species mean values of each variable, growing in stable soil moisture and generally darker environments (longer nights and lower incident radiation), on average. Evolutionary transformations between bipinnate and phyllodinous adult foliage exhibit asymmetry across the Acacia phylogeny, with transformations from bipinnate leaves to phyllodes occurring times faster than the reverse. At least three (and up to seven) transitions from phyllode to bipinnate adult foliage were inferred. Foliage type in the most recent common ancestor of extant Acacia is unresolved, some analyses favour a phyllodinous ancestor, others a bipinnate ancestor. Most ancestral nodes inferred as having bipinnate adult foliage had median age estimates of less than 5 million years (Ma), half having ages between 3 and 1.5 Ma. Acacia lineages with bipinnate adult foliage diversified during the Pliocene, perhaps in response to wetter climatic conditions experienced by the continental margin during this period.