The phylogenetic positions of two species from Lord Howe Island assigned to the genus Grammitis, G. nudicarpa and G. pulchella, and two small Australian grammitid fern genera, Aenigmatogrammitis and Howeogrammitis, were investigated through phylogenetic analyses of atpB, rbcL, rps4–trnS, trnG–trnR and trnL–trnF chloroplast sequences. Grammitis nudicarpa and G. pulchella were shown to be misplaced in Grammitis, instead being placed in a clade comprised of Archigrammitis, Oreogrammitis and Prosaptia. A new genus, Phaneroloma, is here described to accommodate those two species. Descriptions of both Phaneroloma species and an identification key to the species is provided. The phylogenetically isolated positions of Aenigmatogrammitis stenophylla and Howeogrammitis diminuta previously found with fewer chloroplast markers were confirmed, supporting their continued recognition as separate genera.

<italic> Capparis </italic> comprises ~145 species, of which ~21 occur in Australia; however, the relationships and taxonomic status of Australian <italic> Capparis </italic> taxa remain to be tested. We present phylogenies of all Australian <italic> Capparis </italic> taxa by analysing Angiosperms353 loci using coalescent and concatenated approaches. All trees resolve <italic> Capparis </italic> as monophyletic, with a whole-genome duplication (WGD) event detected at the crown. <italic> Capparis </italic> sect. <italic> Capparis </italic> and sect. <italic> Busbeckea </italic> are monophyletic, but sect. <i>Monostichocalyx is non-monophyletic. The relationships of species within sect. <i>Busbeckea are poorly supported due to rapid radiation following ancient WGD. The relationships of taxa within sect. <italic> Capparis </italic> and the clades of sect. <italic> Monostichocalyx </italic> are well-supported, with some incomplete lineage sorting. <italic> Capparis spinosa </italic> is geographically, morphologically and phylogenetically structured across northern Australia. Based on these results, we describe five new species and two new subspecies of <italic> Capparis </italic>, bringing the total number of species in Australia to 26. <italic> Capparis xylocarpa </italic>, <italic> C. megacarpa </italic>, <italic> C. loxophleba </italic> and <italic> C. splendidissima </italic> are newly described. <italic> Capparis loranthifolia </italic> var. <italic> bancroftii </italic> is raised to species level as <italic> C. bancroftii </italic>. <italic> Capparis spinosa </italic> subsp. <italic> nummularia </italic> is re-circumscribed, and two new subspecies, subsp. <italic> formicosa </italic> and subsp. <italic> insularis </italic> are described. We provide a key for all Australian taxa.</i></i>

The angiosperm order Santalales comprises more than 2500 species, most of which are hemi- or holoparasitic on other plants, and derive water and nutrients via specialised structures that attach to host roots or stems. The parasitic lifestyle has affected the morphology and genomes of these plants, and classification of the order has been difficult, with outstanding questions about membership of and relationships between families in the order. We chose to focus on improving phylogenetic sampling in the broadly circumscribed Santalaceae sens. lat., with emphasis on Australasian members of Amphorogynaceae and Viscaceae as part of the Genomics for Australian Plants Initiative. We used target capture with the Angiosperms353 bait set to generate a dataset of 318 nuclear loci × 195 samples, including publicly available data from other Santalales families. Phylogenetic inferences using maximum likelihood concatenation and a summary coalescent approach were largely congruent and resolved relationships between most families, agreeing with much of the previous work on the order. Some relationships that have been difficult to resolve remained so, such as branching order among some families in Olacaceae sens. lat. and Santalaceae sens. lat. Denser sampling in Amphorogynaceae and Viscaceae provided new insights into species-level relationships in genera such as Leptomeria and Choretrum, and allowed testing of recent phylogenetic work in Korthalsella. Our new phylogenetic hypothesis is consistent with one origin of root hemiparasitism, two origins of holoparasitism and five origins of aerial parasitism in the order. Although Angiosperms353 was successful, some phylogenetic bias in gene recovery suggests that future studies may benefit from more specific baits and deeper sequencing, especially for Viscaceae.

The Dicranemataceae was monographed morphotaxonomically by Kraft in 1977, to which the four genera Dicranema Sond., Peltasta J.Agardh., Reptataxis Kraft and Tylotus J.Agardh were attributed. All, save for a species of Tylotus J.Agardh (from east Asia), were endemic to Australia. Additions (in 2006 and 2014 respectively) were the genus Pinnatiphycus N’Yeurt, Payri & P.W.Gabrielson from New Caledonia and Fiji and a new species of Tylotus from Hawaii. General features emphasised by Kraft were similarities of apical and internal structure, zonate tetrasporangia, monoecious gametophytes and placentate cystocarps. The genera did not show uniformity in regard to thallus habits and especially carposporophytes, however, the major differences of which were not accorded any family-level significance. Two later studies, N’Yeurt et al. in 2006 and Kraft et al. in 2014, presented limited molecular data but did not treat the family as a whole or fully resolve relationships between all of the taxa, leaving Kraft’s assumption that the family was monophyletic unchallenged. We address all of the genera, both anatomically and molecularly, and support proposal of two new families, the Peltastaceae and Tylotaceae, in addition to a monogeneric Dicranemataceae. A new genus and species of Peltastaceae, Peltastanomala virantra G.W.Saunders & Kraft, has unique axial and spermatangial anatomies and an unexpected family association with Peltasta. Two additional new genera and species (Chambersius thyrsus G.W.Saunders & Kraft and Huismanophycus marinus G.W.Saunders & Kraft) are even more dissimilar to Peltasta in habit and structure but weakly allied to the Peltastaceae on molecular evidence. Both are therefore regarded as incertae sedis.

Chamelaucieae is a diverse tribe in Myrtaceae with ~800 species in 37 genera distributed across Australia. We applied target capture sequencing using the Angiosperms353 probe set for 131 taxa as part of the Genomics for Australian Plants initiative. Sampling all genera (36) from 10 of 11 named subtribes, we present a phylogenomic analysis for the tribe. This phylogenomic approach has allowed us to better resolve subtribal relationships across the tribe, resulting in an updated classification and additional subtribe (total of 12 subtribes including Triplarininae). Despite these advances, the phylogenetic placements of Stenostegiinae, Astarteinae, and Micromyrtinae remain equivocal and resolution of these relationships should be a focus of future research. We constructed a dated phylogeny from this genomic dataset to investigate the tribe’s biogeographic history and diversification dynamics. We estimate that the crown radiation occurred in the Eocene (c. 42 Ma), with the ancestral area of origin in Australia unresolved. Subsequent divergence and origin of subtribes mostly occurred in south-west Western Australia with frequent dispersals from there into the semi-arid and arid interior since the Miocene (20 Ma). Dispersals out of northern and eastern Australia were limited and confined to dispersal events into the arid interior. Using paleoenvironmental diversification models we show that after the initial radiation, diversification in Chamelaucieae declined rapidly until the Eocene–Oligocene boundary extinction pulse event and subsequently more slowly to the present, with a modest increase during the Middle Miocene Climatic Optimum. No significant diversification rate shifts were detected within clades except within the subtribe Chamelauciinae. There was no significant geographic-dependent diversification in the tribe. Our results add to the growing literature revealing that high plant diversity in south-west Western Australia is due to more time for species accumulation attributed to long-term climatic stability rather than elevated diversification rates.

Zieria obcordata A.Cunn. (Rutaceae), an endangered species endemic to central New South Wales, Australia, faces significant conservation challenges due to limited occurrence in two small, isolated populations. Using genome-wide SNPs (DArTseq), we examine genetic relationships and diversity within and between these populations, and make comparisons with other Zieria species. Our results confirm that Z. obcordata is a distinct species, with the Bathurst and Wellington populations showing sufficient genetic divergence to warrant recognition as two subspecies: Z. obcordata subsp. obcordata and Z. obcordata subsp. wuuluman (formally described here). Minor morphological differences further support this classification. Genomic analyses reveal minimal gene flow between the subspecies, along with extremely low heterozygosity and high inbreeding coefficients within each. Compared to other Zieria species, including Z. covenyi, Z. cytisoides, Z. laevigata, Z. odorifera and Z. smithii, both subspecies exhibit exceptionally low genetic diversity, likely due to geographic isolation, genetic drift and inbreeding. We provide conservation assessments for both subspecies and conclude that each qualifies to be listed as Critically Endangered under the New South Wales Biodiversity Conservation Act 2016. We recommend strategies to facilitate gene flow between the subspecies to improve genetic diversity and enhance fitness.

Archer’s sedge (Carex archeri Boott) is a small, rare (or possibly overlooked by collectors due to the diminutive size) species restricted to alpine and subalpine habitats in south-eastern mainland Australia and Tasmania. The systematic placement has been obscure with the species having been historically associated with sections in four of the six recognised Carex subgenera. We investigated the placement of C. archeri by addition to the available Carex molecular phylogenetic framework. Our results support C. archeri belonging to sect. Junciformes (in subg. Psyllophorae), making this the only representative of the subgenus in Australia. This placement was first proposed by Kükenthal (1909) who regarded C. archeri as a synonym of the New Zealand endemic C. acicularis Boott but our phylogenetic analyses support C. archeri as a separate taxon. Our approach highlights the utility of molecular barcoding for elucidating systematic relationships of poorly known taxa. Biogeographic reconstruction suggests Late Miocene dispersal from South America to the south-western Pacific but does not clarify whether New Zealand or Australia was colonised first. We evaluate the conservation status of Carex archeri using IUCN criteria as Endangered at the global level. At the state level, we propose Critically Endangered status in New South Wales, Endangered in Victoria and Data Deficient in Tasmania.

Tribe Anthemideae (Asteraceae) is represented in Australia by only nine indigenous species of Cotula and Leptinella. The generic placement of Cotula alpina (Hook.f.) Hook.f. is considered problematic, because it shares the stoloniferous and scapose habit of Leptinella, but lacks corollas in female florets, a trait traditionally considered defining of Cotula. A previous phylogenetic analysis of Leptinella using ITS and chloroplast data showed that the species nested in that genus, but some uncertainty remained because of incomplete sequence data and missing cytological information, and no taxonomic change was made. Here, we use target-capture data from three different sequencing initiatives to reconstruct a phylogeny of Australian native and introduced Anthemideae to resolve this outstanding question. We confirm previous results with a high degree of support and formally transfer Cotula alpina to the genus Leptinella. A lectotype is selected for the basionym, Ctenosperma alpinum Hook.f.

Ongoing taxonomic studies of Australian marine algae have led to the recognition of a new species of the green algal genus Rhipilia, here named R. psammophila Huisman & Verbruggen. The new species is unusual for this typically tropical genus in growing in the colder temperate waters of southern Australia and can be distinguished from its congeners by the morphology of its laterally adhering siphons, in addition to unique molecular sequences (rbcL and tufA). In molecular analysis, the new species is sister to the southern Australian Chlorodesmis baculifera, which is here transferred to Rhipilia and represents the third species in the genus with laterally unattached, free siphons, a feature that previously would have excluded it from the genus. Lateral gametangia are described for R. psammophila and represent the first record of reproduction in Rhipilia.

This study of Northern Territory charophytes documents 22 species in 3 of the genera in tribe Chareae, family Characeae, including 15 previously described species (Chara benthamii, C. erythrogyna, C. globularis, C. karolii, C. lucida, C. porteri, C. protocharoides, C. setosa, C. submollusca, C. wightii, C. zeylanica, Lamprothamnium capitatum, L. compactum, L. stipitatum, Lychnothamnus barbatus) of which 2 are new for the Australian flora (C. erythrogyna and C. wightii), as well as 5 varieties raised to species rank (C. aridicola, C. arnhemensis, C. bancroftii, C. behriana, C. duriuscula), and 2 newly described species (C. lamprothamniformis, C. schultae). Three previously reported species in the tribe (C. braunii, C. corallina, C. fibrosa) are not recorded from the Northern Territory in this study, as previous records were based on erroneous identifications or localities. Although Northern Territory specimens of Lychnothamnus barbatus have not been seen, it has been included in this treatment, because it occurs in south-eastern Queensland, the Gulf of Carpentaria, Papua New Guinea and Timor-Leste. A key, illustrations and descriptions of all the species are provided.