A new species of Eulimnadia is described from roadside table drains 51 km NNW of Moree, northwestern NSW. It is an androdioecious species with the characteristic spiniform projection at the ventroposterior angle of the telson, the cercopod divided into two unequal sections by a spine and only eight antennomeres in each flagellum of the second antenna. The egg, its most characteristic feature, is cylindrical and somewhat distorted by an incomplete second band of ridges and grooves, making it the second Australian species with a cylindrical egg.

Laevicaudatan branchiopods, also called ‘smooth clam shrimps’ or ’pea shrimps’, are rare crustaceans found exclusively in temporary, small freshwater bodies, which stay dry most of the year. Only 42 laevicaudatan species have been described so far, 90% of which belong to the genus Lynceus . The first multilocus phylogeny of the group is provided here, based on 15 Lynceus species from North and South America, Europe, Africa, Asia, Australia and New Caledonia and using nine molecular markers (two mitochondrial and seven nuclear genes, including newly designed primers). Genetic data suggest populations of Lynceus brachyurus from Europe and North America to represent a complex of cryptic species and sister group to all other laevicaudatans. Species from Thailand, Japan, Mongolia and China formed a distinct East Asian clade. A Southern Hemisphere (Gondwanaland) clade, composed of Chilean, Australian and New Caledonian taxa, was found weakly clustering with an African Lynceus species. Relaxed molecular clock analyses indicate a Pangean origin of Laevicaudata, with further diversification due to vicariance and the continued splitting of continents. Rostrum characters, which are particularly relevant for laevicaudatan systematics, were re‐evaluated and provide morphological evidence supporting molecular clades. Our worldwide overview of Laevicaudata evolution highlights that recent sampling from Africa and South America is scarce, and that further DNA efforts should focus on Paralimnetis and Lynceiopsis species.

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.

A new fairy shrimp, Branchinella rosalieae n.sp., is described from a claypan within Alice Springs, Northern Territory. Its frontal appendage is like other members of the B. affinis group, consisting of a central trunk divided terminally into two substantial branches but distinctively with sensory papillae only along its medial margin. Other male characteristics are unremarkable and the female is like many others in Branchinella. The egg is spherical with close set polygons, like that in many species of Branchinella.

Inland saline lakes are well known to be less biodiverse than fresh waters. In Australia, the most important driver affecting biodiversity is salinity that imposes an inverse linear relationship. However, in detailed studies across a wide salinity spectrum, the relationship is scale dependent. This is mediated in part by the range of salinity tolerated becoming broader as the maximum tolerated salinity increases. Other factors of importance sometimes include hydrology, habitat heterogeneity, season, pH and oxygen, but these are usually not easy to quantify. Even rarer is the influence of colonisation by marine organisms, which is applicable only at some sites near the coastline and the influence of ionic proportions on the presence of some species and, hence, diversity. The contribution of predation or competition on diversity, reported in some overseas salinas, is suspected but yet to be proved in Australia. The crustacean component in saline lakes is more influenced by these drivers than is most of the insect fraction.

Abstract 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, and also creek pools 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 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 climes of the Western Australian Wheatbelt where hydroperiods more stable.

Clam shrimps of the genus Paralimnadia living in small pools of the eastern highlands are particularly variable between populations. A detailed study of many populations of P. urukhai in the northern New England Tablelands revealed almost random variation in normally conservative characters such as egg morphology and cercopod setae as well as wide variation in other less defining characters. This necessitates a revised description of this species. This redescription focuses only on the Stanthorpe group of populations as previous genetic analysis suggests the Bald Rock populations could represent a separate species, but the two cannot be separated presently based on morphological features. However, two populations 100 km to the south are morphologically and genetically distinct enough to constitute a new species which we describe herein. All these populations live in isolated rock pools within forests where dispersal is difficult, so that retained founder effects and local adaptation are probably directing interpopulation variability.

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.

The majority of Australian Spinicaudata Linder, 1945 inhabit the (semi)arid deserts of Australia's lowlands. However, several closely related species of Paralimnadia Sars, 1896 inhabit small temporary habitats throughout the Great Dividing Range in eastern Australia. By combining analyses of mitochondrial cytochrome c oxidase subunit I (COI) with double-digest restriction-site associated DNA (ddRAD) data, we studied the species diversity and genetic diversity of this group of mountain-dwelling branchiopods. Levels of genetic differentiation in COI are relatively low between putative species (mostly between 1.5 and 6.7%), complicating COI-based species delimitation. Depending on the applied threshold, three to six species are inferred in the studied area, with most putative species being geographically restricted. Particularly notable are the high levels of population differentiation indicated by ddRAD analyses between nearby populations within putative species. This suggests that gene flow is limited, even between populations separated only by a few kilometres. This maylead to fast population differentiation, which in turn might drive speciation. Our data suggest that the species diversity of Paralimnadia in the Great Dividing Range is much higher than currently appreciated.

Clam shrimps of the genus Paralimnadia living in small pools of the eastern highlands are particularly variable between populations. A detailed study of many populations of P. urukhai in the northern New England Tablelands revealed almost random variation in normally conservative characters such as egg morphology and cercopod setae as well as wide variation in other less defining characters. This necessitates a revised description of this species. This redescription focuses only on the Stanthorpe group of populations as previous genetic analysis suggests the Bald Rock populations could represent a separate species, but the two cannot be separated presently based on morphological features. However, two populations 100 km to the south are morphologically and genetically distinct enough to constitute a new species which we describe herein. All these populations live in isolated rock pools within forests where dispersal is difficult, so that retained founder effects and local adaptation are probably directing interpopulation variability.

Rock pools (gnammas) have a random distribution on rock pavements over much of Australia. In the climatically benign south, they are common and have a diverse fauna, but those in deserts are rarer, structurally different and scarcely surveyed. A widely spaced set of gnammas in the Gibson Desert of Western Australia were sampled in mid-2017 and again in mid-2018 using a pond net and a plankton net. The gnammas are in lateritic rock, and have a distinctive pipe-like form and mode of origin. The latter involves vertical solution of weathered rock, aided by kangaroos excavating for water as the pools dry. This is different from the granite pans and pits in southern Australia. Mean alpha diversity of macroinvertebrate communities in these mid-Western Australian gnammas is 5.9 species, drawn from a metacommunity of eight crustacean species, with perhaps a few insect individuals from an array of 21 species (gamma diversity). Invertebrate dispersal is extremely limited with crustaceans surviving dry periods as passively distributed eggs and insects recolonising actively from the wetter west during each filling event. Poor dispersal, plus the small size and homogeneity of habitat within the pipe gnammas, limits biotic diversity.

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.

A redescription of Eulimnadia rivolensis (Brady, 1886) (Branchiopoda: Spinicaudata: Limnadiiidae), and its transfer to Paralimnadia.Memoirs of Museum Victoria 78: 57

While the fauna of Australian salt lakes is now well-known, seasonal phenological patterns of invertebrates are not. Two studies on saline lakes in southern Australia suggest the lakes fill in early winter and remain at salinities characteristic for each lake during winter-spring before elevating and drying in summer. The fauna is dominated by crustaceans with few insects and all component species are present most of the time and randomly fluctuating in numbers. Lakes in the southern inland（mainly Lake Eyre） fill in summer, change little in salinity until near drying, and are dominated by crustaceans but have some insects. By contrast temporary salinas in the central inland fill episodically mainly in summer and then their salinity increases steadily as they dry without further rain. Their fauna is also dominated by crustaceans, but with a significant insect component and composition varies though the hydrological cycle. This study reports on an unusual winter fill in two central Paroo lakes and two pools, in which the crustacean fauna is similar to that in summer but insects are delayed till late spring and are not as common as in summer fills. It seems therefore that while insects are more restricted by medium and high salinities than crustaceans, they are also more restricted by cooler temperatures than crustaceans.

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.

The original type species of Australimnadia is made a junior synonym of A. grobbeni, originally described as Limnadia grobbeni Daday, 1925. A second species of Australimnadia is described from Onslow, Western Australia; it differs in having unique egg morphology and is distinct in many morphological characters, including those of the telson and cercopod, but also of the thoracopods. Its validity is confirmed by molecular differences between the two species in COI and EF1α. A third species from southwestern Western Australia is separated morphologically by unique spination of the telson and setation of the cercopod, and by its egg morphology.

Branchinella occidentalis (Dakin 1914) is redescribed from material collected across the species natural distribution, with special attention to its functional morphology in relation to predatory feeding behaviour observed in the wild and in culture. We present B. occidentalis as a predatory anostracan with physical adaptations convergent with other large predatory anostracan taxa. Comparisons with its closest sister taxon, B. australiensis (Richters 1876), and with other predatory species are made and discussed. Revised and updated definitions and diagnoses for the Thamnocephalidae, Branchinella, and Branchinella sensu stricto are provided.

Eggs in large Branchiopoda are often diagnostic of species and may show some phyletic relationships. Those of the two species of Australobranchipus are described and are easily separable from each other and are particularly distinctive among Australian anostracans, all unrelated. Within its family, the Branchiopodidae however, there is some similarity to two African genera, but not Eurasian species, indicative perhaps of a gondwanan connection.

Branchinella occidentalis (Dakin 1914) is redescribed from material collected across the species natural distribution, with special attention to its functional morphology in relation to predatory feeding behaviour observed in the wild and in culture. We present B. occidentalis as a predatory anostracan with physical adaptations convergent with other large predatory anostracan taxa. Comparisons with its closest sister taxon, B. australiensis (Richters 1876), and with other predatory species are made and discussed. Revised and updated defi nitions and diagnoses for the Thamnocephalidae, Branchinella , and Branchinella sensu stricto are provided.