Aquatic invertebrate community structure and phenology of the intermittent treed swamps of the semi-arid Paroo lowlands in Australia.

The middle Paroo lowlands in semi-arid western New South Wales support numerous intermittent wetlands of various types. Differences between them are promoted by three ecological drivers: salinity, turbidity and hydroperiod. Community structure and phenology of the two most common types, saline lakes and claypans, are known but similar ecologies are lacking for the third most common wetland, the treed swamps. These are of six subtypes distinguished by dominant tree species, geomorphology and hydroperiod, all with similar community structure and phenology, but with differing invertebrate diversities. Summed diversity is not as high as in local creek pools, the shorter hydroperiods and simpler geomorphology of the treed swamps being restrictive so that there is almost no replacement of species during the early dominance of branchiopods and later of insects. Such treed swamps are uncommon in the semi-arid zone, but much more speciose treed swamps are known under similar and seasonally dry Mediterranean climates of the Western Australian Wheatbelt where hydroperiods are more stable. Supplementary Information: The online version contains supplementary material available at 10.1007/s11273-021-09846-0.

Diagnosing Eulimnadia and Paralimnadia (Branchiopoda: Spinicaudata: Limnadiidae).

Eulimnadia and Paralimnadia are both strongly supported, monophyletic limnadiid lineages based on molecular studies. However, defining the two taxa morphologically relies on the presence/absence of a subcercopodal spiniform projection; otherwise there is considerable overlap and confusion in morphological characters between the two taxa. The most discriminatory of these characters are examined here and applied to Australasian species. As a result, five Eulimnadia species are transferred to Paralimnadia. These characters are then applied to world Eulimnadia species and other limnadiid genera which share key features with Eulimnadia.

Three new species of spinicaudatan clam shrimps from Australia, all from gnammas (rock pools).

Recent collections from the remote Kimberley in Western Australia, have added three species to the known fauna of gnammas, Limnadopsis multilineata Timms, 2009 and two new species described herein, Eulimnadia kimberleyensis sp. nov. and Ozestheria pellucida sp. nov.. A further gnamma icon, Paralimnadia laharum sp. nov. is added from the Grampians in western Victoria. The numerous records of clam shrimps from Australian gnammas are examined.

A review of the Australian endemic clam shrimp, Paralimnadia Sars 1896 (Crustacea: Branchiopoda: Spinicaudata).

Paralimnadia was recently re-erected to accommodate Australian limnadiids formally placed in Limnadia. They are characterised by the lack of a spine on the posterior ventral corner of the telson, a cercopod divided by a spine midlength into a cylindrical seta bearing basal section and a narrowing denticle bearing distal section, males amplex females on the posterior body margin keeping the body in line, and gonochoristic reproduction, so typically sex ratios are broadly 1:1. These characters separate Paralimnadia from the closely related Eulimandia. Paralimnadia is endemic to and diverse in Australia, and includes the transferred P. stanleyana (King), P. sordida (King), P. badia (Wolf), P. cygnorum (Dakin) and P. urukhai (Webb & Bell) as well as 10 new species. All are variable morphologically, the most conservative characters being the morphology of their eggs and the cercopod setae. Although found across Australia, there are hot spots of diversity in the coast and montane areas of New South Wales and southwest of areas of Western Australia and few in the vast inland arid zone. As in Eulimnadia, a few occur in rock pools. However those in sandy coastal pools subject to urbanisation or mining are becoming rare.

A partial revision of the Australian Eulimnadia Packard, 1874 (Branchiopoda: Spinicaudata: Limnadiidae).

The worldwide genus Eulimnadia previously with only five species described from Australia, is known now to have at least 15 endemic species plus about 10 undescribed species detected by molecular means. Most have variable morphological features, though each has a distinctive resting egg morphology. Many occur in the known branchiopod hot spot of the Paroo/Bulloo catchments in western New South Wales and Queensland. Some are specific to gnammas (rock holes). Given the rarity of males, androdioecious reproduction is probable in most species. Keys are provided for all known Australian species.

Anostracan (Crustacea: Branchiopoda) zoogeography III. Australian bioregions .

Anostracan bioregions were identified for Australia. These regions were quantitatively defined using species distributions compared through Jaccard's Coefficient of Community Similarity, and qualitatively defined using regional soils data. Community assemblages are quantified using Fager's Index of Recurring Species Groups. Substrate geochemistry was used to investigate additional relationships, but was limited by the constraints of available data. However, the highly salinized soils directly relate to Australia bearing the highest diversity of halophilic anostracan taxa. Three anostracan biogeographical regions are defined for Australia: Western, Eastern and Southern. 

A revision of the Australian species of Lynceus Müller, 1776 (Crustacea: Branchiopoda: Laevicaudata, Lynceidae).

Australia has had two species of Lynceus, L. macleayanus (King, 1855) and L. tatei (Brady, 1886) reported to date, both poorly described and without types, and supposedly both widely distributed. This study establishes neotypes and redescribes each according to modern standards. The present distribution of each is severely restricted by the destruction of temporary aquatic habitats, both in cities and in the country and also misunderstood by the lack of recent collecting in some outlying areas. Detailed study of male first thoracopods, together with an understanding of the form of the head and rostrum, antenna 2 spinal patterns, carapace shape, and the females' lamina abdominalis, most of which are discontinuously variable, has resulted in the delineation of four more species: L. baylyi sp. nov. in desert rockholes of Western Australia; L magdaleanae sp. nov. mainly in deep gnammas of the WA Wheatbelt and Goldfields but also extending into NT, Qld and SA; L. susanneae sp. nov. of rockholes on the Nullarbor Plain, WA; and L. argillaphilus sp. nov. of the coastal Pilbara, WA. Identification keys are provided for all six species, both males and females.

Cyclestheria hislopi (Crustacea: Branchiopoda): a group of morphologically cryptic species with origins in the Cretaceous.

Cyclestheria hislopi is thought to be the only extant species of Cyclestherida. It is the sister taxon of all Cladocera and displays morphological characteristics intermediate of Spinicaudata and Cladocera. Using one mitochondrial (COI) and two nuclear (EF1α and 28S rRNA) markers, we tested the hypothesis that C. hislopi represents a single circumtropic species. South American (French Guiana), Asian (India, Indonesia, Singapore) and several Australian populations were included in our investigation. Phylogenetic and genetic distance analyses revealed remarkable intercontinental genetic differentiation (uncorrected p-distances COI>13%, EF1α>3% and 28S>4%). Each continent was found to have at least one distinct Cyclestheria species, with Australia boasting four distinct main lineages which may be attributed to two to three species. The divergence of these species (constituting crown group Cyclestherida) was, on the basis of phylogenetic analyses of COI and EF1α combined with molecular clock estimates using several fossil branchiopod calibration points or a COI substitution rate of 1.4% per million years, dated to the Cretaceous. This was when the South American lineage split from the Asian-Australian lineage, with the latter diverging further in the Paleogene. Today's circumtropic distribution of Cyclestheria may be best explained by a combination of Gondwana vicariance and later dispersal across Asia and Australia when the tectonic plates of the two continents drew closer in the early Miocene. The lack of morphological differentiation that has taken place in this taxon over such a long evolutionary period contrasts with the high level of differentiation and diversification observed in its sister taxon the Cladocera. Further insights into the evolution of Cyclestheria may help us to understand the evolutionary success of the Cladocera.

Flying with the birds? Recent large-area dispersal of four Australian Limnadopsis species (Crustacea: Branchiopoda: Spinicaudata).

Temporary water bodies are important freshwater habitats in the arid zone of Australia. They harbor a distinct fauna and provide important feeding and breeding grounds for water birds. This paper assesses, on the basis of haplotype networks, analyses of molecular variation and relaxed molecular clock divergence time estimates, the phylogeographic history, and population structure of four common temporary water species of the Australian endemic clam shrimp taxon Limnadopsis in eastern and central Australia (an area of >1,350,000 km(2)). Mitochondrial cytochrome c oxidase subunit I sequences of 413 individuals and a subset of 63 nuclear internal transcribed spacer 2 sequences were analyzed. Genetic differentiation was observed between populations inhabiting southeastern and central Australia and those inhabiting the northern Lake Eyre Basin and Western Australia. However, over large parts of the study area and across river drainage systems in southeastern and central Australia (the Murray-Darling Basin, Bulloo River, and southern Lake Eyre Basin), no evidence of population subdivision was observed in any of the four Limnadopsis species. This indicates recent gene flow across an area of ∼800,000 km(2). This finding contrasts with patterns observed in other Australian arid zone taxa, particularly freshwater species, whose populations are often structured according to drainage systems. The lack of genetic differentiation within the area in question may be linked to the huge number of highly nomadic water birds that potentially disperse the resting eggs of Limnadopsis among temporary water bodies. Genetically undifferentiated populations on a large geographic scale contrast starkly with findings for many other large branchiopods in other parts of the world, where pronounced genetic structure is often observed even in populations inhabiting pools separated by a few kilometers. Due to its divergent genetic lineages (up to 5.6% uncorrected p-distance) and the relaxed molecular clock divergence time estimates obtained, Limnadopsis parvispinus is assumed to have inhabited the Murray-Darling Basin continuously since the mid-Pliocene (∼4 million years ago). This means that suitable temporary water bodies would have existed in this area throughout the wet-dry cycles of the Pleistocene.

Toward a global phylogeny of the "living fossil" crustacean order of the Notostraca.

Tadpole shrimp (Crustacea, Notostraca) are iconic inhabitants of temporary aquatic habitats worldwide. Often cited as prime examples of evolutionary stasis, surviving representatives closely resemble fossils older than 200 mya, suggestive of an ancient origin. Despite significant interest in the group as 'living fossils' the taxonomy of surviving taxa is still under debate and both the phylogenetic relationships among different lineages and the timing of diversification remain unclear. We constructed a molecular phylogeny of the Notostraca using model based phylogenetic methods. Our analyses supported the monophyly of the two genera Triops and Lepidurus, although for Triops support was weak. Results also revealed high levels of cryptic diversity as well as a peculiar biogeographic link between Australia and North America presumably mediated by historic long distance dispersal. We concluded that, although some present day tadpole shrimp species closely resemble fossil specimens as old as 250 mya, no molecular support was found for an ancient (pre) Mesozoic radiation. Instead, living tadpole shrimp are most likely the result of a relatively recent radiation in the Cenozoic era and close resemblances between recent and fossil taxa are probably the result of the highly conserved general morphology in this group and of homoplasy.

Phylogeny of Spinicaudata (Branchiopoda, Crustacea) based on three molecular markers--an Australian origin for Limnadopsis.

Taxonomy and phylogeny within the branchiopod taxon Spinicaudata are still controversial. We analyzed sequences of three gene fragments (28S rRNA, 16S rRNA and COI) from up to 41 species of the Cyzicidae, Limnadiidae and Leptestheriidae to infer their phylogenetic relationships, focusing in particular on species from Australia and their phylogenetic position within Spinicaudata. Four major monophyletic lineages could be distinguished: Limnadiidae, Leptestheriidae, Eocyzicus and all Cyzicidae except Eocyzicus. A clear genetic distinction between Australian and non-Australian Cyzicidae is well supported (i.e. Caenestheria and Caenestheriella species from Australia and Caenestheriella and Cyzicus species from Europe, Asia and North America). In the genera Eocyzicus and Eulimnadia the Australian species were closely related to those from other continents. The species of the Australian endemic genus Limnadopsis and Australian Limnadia species form a monophylum. This suggests that the origin of Limnadopsis lies in Australia and that Limnadia is not monophyletic.