Quantitative macroinvertebrate bioassessment in seasonally astatic aquatic habitats, Part I. Quantitative method.

Seasonally astatic aquatic habitats are important ecologically, municipally, and agriculturally. Regulatory agencies and conservation organizations have developed various plans for protecting or constructing temporary wetlands, resulting in habitat monitoring requirements, particularly as relates to restoration and constructed habitats. Unfortunately, there has been no effort to develop a unified, consistent method for wetland biological monitoring. This is particularly true for habitats important in a regulatory sense. We conducted macroinvertebrate bioassessment in constructed vernal pools in California, USA, to assess habitat functionality. This tool is modified from aquatic bioassessment; a primary tool of regulatory agencies in measuring habitat health and water quality and should be equally applicable to seasonally astatic wetlands globally.

Quantitative macroinvertebrate bioassessment in seasonally astatic aquatic habitats, Part II. Applying the method.

Seasonally astatic aquatic habitats are important ecologically, municipally, and agriculturally. Regulatory agencies and conservation organizations have developed various plans for protecting or constructing temporary wetlands, resulting in habitat monitoring requirements, particularly as relates to restoration and constructed habitats. Unfortunately, there has been no effort to develop a unified, consistent method for wetland biological monitoring. In Part I, we presented a quantifiable, replicable method for assessing seasonally astatic wetlands, which would allow for direct comparison between individual wetlands, wetland sites, and wetland types. Here in Part II, we apply the method and present the results from more than a decade of a data on two disparate sites that support California vernal pool habitats. These habitats include natural, restored, and constructed vernal pools. Our results demonstrate that the method we present yields reliable, statistically useful, and actionable data and provides a better method for assessing astatic wetland ecological health and the persistence of federally listed vernal pool crustaceans than other methods so far employed.

Parartemiopsisshangrilaensis, a new species of fairy shrimp (Branchiopoda, Anostraca) from Yunnan, with a key to the Chirocephalidae of China.

The fairy shrimp genus Parartemiopsis Rogers, 2005 currently contains a single species reported from Russia and Mongolia. In 2013, an unidentified Parartemiopsis population was reported from the eastern margin of the Tibetan Plateau in China's Yunnan Province, from Patatson National Park in Shangri-La County. Here, we describe the Chinese populations as a new species, Parartemiopsisshangrilaensissp. nov. This new species is distinguished from its congener, P.longicornis (Smirnov, 1930), by the form of the male second antennae and the gonopod. The discovery of P.shangrilaensissp. nov. extends the known distribution of the genus, and more Parartemiopsis species may be found in the future. We present a key to the genera and species of Chirocephalidae in China as an aid to future research.

Investigating Vernal Pool Fairy Shrimp Exposure to Organophosphate Pesticides: Implications for Population-Level Risk Assessment.

Vernal pool fairy shrimp, Branchinecta lynchi, is a freshwater crustacean endemic to California and Oregon, including California's Central Valley. B. lynchi is listed as a Federally Threatened species under the US Endangered Species Act, and as a vulnerable species on the IUCN Red List. Threats that may negatively impact vernal pool fairy shrimp populations include pesticide applications to agricultural land use (e.g., agrochemicals such as organophosphate pesticides) and climate changes that impact vernal pool hydrology. Pop-GUIDE (Population model Guidance, Use, Interpretation, and Development for Ecological risk assessment) is a comprehensive tool that facilitates development and implementation of population models for ecological risk assessment and can be used to document the model derivation process. We employed Pop-GUIDE to document and facilitate the development of a population model for investigating impacts of organophosphate pesticides on vernal pool fairy shrimp populations in California's Central Valley. The resulting model could be applied in combination with field assessment and laboratory-based chemical analysis to link effects from pesticide exposure to adverse outcomes in populations across their range. B. lynchi has a unique intra-annual life cycle that is largely dependent upon environmental conditions. Future deployment of this population model should include complex scenarios consisting of multiple stressors, whereby the model is used to examine scenarios that combine chemical stress resulting from exposure to pesticides and climate changes.

Preliminary Study of Temperature Effects on Size and Shape in the Modern Spinicaudatan Eulimnadia texana (Crustacea: Branchiopoda).

Studies of temperature effects on morphology in Spinicaudata have focused on length, with no data on shape. To fill this gap, size and shape variability in response to temperature fluctuations was investigated by rearing the modern spinicaudatan Eulimnadia texana. Two days after hydration, juvenile individuals were separated into four different temperature treatments: 20°C, 23°C, 26°C, and 29°C. Hermaphrodite size and shape were analysed by looking at linear combinations of size variables and using Fourier shape analysis; methods that are also used to describe fossil size and shape for better comparison. Size differences were considerable, with reduced growth at low and high temperatures and accelerated growth at the optimum temperature of 26°C, revealing that the reaction of size to increasing temperature is non-linear. The height of the dorsal margin, which is associated with space for egg production in Eulimnadia texana, accounts for a high amount of size variability in this species and, presumably, in most of the Limnadiidae. Hermaphrodite shapes reared under temperatures of 20°C and 29°C are statistically distinct, while intermediate temperatures yield intermediate shapes. The rate of shape change along temperature is comparatively low between 23°C and 26°C and accelerated at lower and higher temperatures. With increasing temperature, the highest point of the dorsal margin is shifted towards the anterior of the carapace, while it assumes a median position at 20°C. Our result that temperature has strong effects on carapace size and shape implies considerable ecophenotypic variability in Spinicaudata.

Review of the southern African Leptestheriidae (Branchiopoda: Spinicaudata) I: redescription of Leptestheria brevirostris Barnard, 1924 with comments on diagnostic characters.

We present the first records of Leptestheria brevirostris since its discovery in Namibia by Barnard in 1924. Our records come from Botswana and South Africa, and present significant range extensions. We redescribe L. brevirostris according to modern standards and present the first description of the male. We also discovered that L. brevirostris is likely a rock pool specialist, specific to sandstone and gneiss outcrops; this is the first record of a rock pool specialist clam shrimp from Africa and the second rock pool specialist described for Leptestheriidae. Finally, we depict and discuss the validity and usefulness of diagnostic characters for Leptestheria species in southern Africa, especially the usefulness of carapace interval ornamentation.

The complete mitogenome of Leptestheria brevirostris Barnard, 1924, a rock pool clam shrimp (Branchiopoda: Spinicaudata) from Central District, Botswana.

Spinicaudatan clam shrimp are a widespread and diverse group of branchiopod crustaceans, yet few mitochondrial genomes have been published for this taxonomic group. Here, we present the mitogenome of Leptestheria brevirostris from a rock pool ecosystem in Botswana. Massively parallel sequencing of a single specimen facilitated the reconstruction of the species' 15,579 bp circularized mitogenome. The reconstructed phylogenetic tree confirms that L. brevirostris forms a monophyletic group with other diplostracan branchiopods, and that these are the sister taxon to Notostraca. The mitogenome reconstructed here is the first to be reported from a leptestherid clam shrimp.

Fossil and Modern Clam Shrimp (Branchiopoda: Spinicaudata, Laevicaudata): The World's First Clam Shrimp Symposium and a Celebration of Brian V. Timms.

This special volume of Zoological Studies is the result of a symposium entitled "Fossil and Modern Clam Shrimp" held at the midyear meeting of The Crustacean Society in May of 2019. This symposium is the first ever focusing on clam shrimp, and the first conference where both palaeontologists and biologists specialising in these animals were able to come together. The papers presented here provide insight into the palaeontology, biology, ecology, taxonomy and phylogeny of the clam shrimp. This chapter introduces the symposium, its aims, and the resulting research, presented in the subsequent chapters. In addition, in this symposium we celebrate our great friend Brian V. Timms, who has mentored so many of us, brought us on various excursions across Australia, and has done more to advance Australian branchiopod studies than anyone else in history.

Developmental and Functional Morphology of Eulimnadia braueriana Ishikawa, 1895 (Branchiopoda: Spinicaudata) Feeding Structures: Combination of Filtering and Scraping Feeding Mechanisms.

Large branchiopods inhabit diverse continental habitats worldwide. Their feeding ecology, nevertheless, remains largely unknown. The few functional morphology studies that have been conducted have mostly focused on adults or larvae, seldom have the two been compared collectively. In this study, we examined the feeding structures in Eulimnadia braueriana Ishikawa, 1895 from nauplius to adult to clarify their feeding mechanisms and then compared them with the other two sympatric branchiopods (Branchinella kugenumaensis and Lynceus biformis) in Siangtian Pond, Taiwan. Naupliar second antennae and mandibles are similar to those of other species, suggesting filter-feeding. The naupliar feeding structures, including the mandibular palp and naupliar process, gradually degenerate during the juvenile stage. Simultaneously, the molar surface, maxillae, and second antennae continue developing, reaching their adult form in later juvenile substages. The molar surface and thoracopod setal morphology are similar to those of other filter-feeding branchiopods, but adults also have scraping setae on the first several thoracopod pairs. Nearly all naupliar primary feeding structures change through development, particularly during the early juvenile substages, whereas late juvenile substages and adult morphology are similar. Eulimnadia braueriana transforms from pelagic filtering nauplii to adults that combine benthic filtering and scraping. Comparisons of molar and thoracopod morphology between coexisting branchiopod species show some similarities and differences in filtering and scraping feeding structures, implying potential foraging resource differentiation among species.

Phylogeny and Biogeography of Spinicaudata (Crustacea: Branchiopoda).

Spinicaudata (spiny clam shrimp) is a taxon of Branchiopoda occurring since the Devonian and today it occurs nearly globally in temporary water bodies. We present the most species-rich phylogenetic analyses of this taxon based on four molecular loci: COI, 16S rRNA, EF1α and 28S rRNA. Our results support previous findings that Cyzicidae sensu lato is paraphyletic. To render Cyzicidae monophyletic we establish a fourth extant spinicaudatan family to accommodate Eocyzicus. Within Cyzicidae, none of the genera Cyzicus, Caenestheria or Caenestheriella are monophyletic, and the morphological characters used to define these genera (condyle length and rostrum shape) are not associated with well-delimited clades within Cyzicidae. There is insufficient resolution to elucidate the relationships within Leptestheriidae. However, there is sufficient evidence to show that the leptestheriid genera Eoleptestheria and Leptestheria are non-monophyletic, and there is no support for the genus Leptestheriella. Molecular clock analyses suggest that the wide geographic distribution of many spinicaudatan taxa across multiple continents is largely based on vicariance associated with the break-up of Pangea and Gondwana. Trans-oceanic dispersal has occurred in some taxa (e.g., Eulimnadia and within Leptestheriidae) but has been relatively rare. Our results highlight the need to revise the taxonomy of Cyzicidae and Leptestheriidae and provide evidence that the global spinicaudatan diversity may be underestimated due to the presence of numerous cryptic species. We establish Eocyzicidae fam. nov. to accommodate the genus Eocyzicus. Consequently, Cyzicidae comprises only two genera -Cyzicus and Ozestheria. Ozestheria occurs also in Africa and Asia and Ozestheria pilosa new comb. is assigned to this genus.

The complete mitogenome of the fairy shrimp Streptocephalus cafer (Lovén, 1847) (Crustacea: Branchiopoda: Anostraca) from an ephemeral pond in Botswana, southern Africa.

Fairy shrimps (Anostraca) constitute an important component of seasonally aquatic habitats, but few complete mitochondrial genomes have been published for this group. Here, we report the mitogenome of a common southern African species, Streptocephalus cafer, from Botswana (accession number: MN720104). Low-coverage shotgun sequencing recovered two contigs 15653 bp and 1347 bp in length that are separated by a repetitive region of unknown length within the non-coding control region. The mitogenome's GC content is 31.80%. Phylogenetic analysis using protein-coding genes confirms the sister taxon relationship of S. cafer with the only other congener whose mitogenome has been reconstructed to date, the Asian S. sirindhornae.

The complete mitogenome of an undescribed clam shrimp of the genus Gondwanalimnadia (Branchiopoda: Spinicaudata), from a temporary wetland in Central District, Botswana.

Clam shrimps (Spinicaudata) are a widespread and diverse crustacean group that frequent temporary aquatic habitats, but few complete mitochondrial genomes have been published for this group. Here, we report the mitogenome of an undescribed Gondwanalimnadia species from Botswana. Raw sequences were assembled into a single circular genome with a total length of 15,663 bp. Thirteen protein-coding genes, 22 tRNAs, and 2 rRNAs were identified using the MITOS pipeline. The mitogenome's GC content is 33.52%. Phylogenetic analysis using protein-coding genes confirmed that Gondwanalimnadia sp. is closely related to another member of the Limnadiidae, Limnadia lenticularis.

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.

Distribution of Clam Shrimps (Crustacea: Laevicaudata and Spinicaudata) in South Africa, with New Records from the Northern Cape Province.

The ephemeral waterbodies of southern Africa are regarded a global hotspot for large Branchiopod diversity. Although the distributions and systematics of Anostraca and Notostraca have been fairly well defined, clam shrimps have received much less attention. So far, 18 clam shrimp species are known from the sub-region, but none of the available published literature defines their distribution in South Africa. Furthermore, most of the recent studies were concentrated in the mesic provinces, while very little information is available from the Northern Cape, where most ephemeral waterbodies in the country occur. This study reviews the distribution of clam shrimps in South Africa by reviewing published distribution records and contributing novel data from surveys in the Northern Cape. We found that 13 of the 18 species from the sub-region occur in South Africa, of which four are restricted to their respective provinces. We further clarify the current state of endemism patterns in South Africa and provide novel findings from the Northern Cape, including three new range extensions. The Northern Cape hosts the highest species richness, with nine species, followed by the Eastern Cape, where seven species have been recorded so far. Most other provinces have low species richness and endemism, while no species records have been published from the Limpopo province yet. Surveys over large geographical scales are important, and more research is needed on clam shrimp systematics in South Africa.

Review of the Eulimnadia (Branchiopoda: Spinicaudata: Limnadiidae) of Tropical Asia, with the Description of a New Species.

We describe a new species of Eulimnadia from the Oriental region using museum specimens collected from India and fresh material from Thailand. This species has egg morphology resembling E. magdalensis s. lat. and E. chaperi, but distinctly differs from them by presence of a narrow depression at the polygon floor. We also comment on the species status of E. khoratensis from Thailand based on egg morphology, and present a taxonomic key for identification of tropical Asian species of Eulimnadia.

A New Eulimnadia (Branchiopoda: Spinicaudata: Limnadiidae) from the US Virgin Islands.

We describe a new species of Eulimnadia from the Caribbean using fresh material from the island of St Thomas. Originally reported in 2003 as a Eulimnadia cf. texana (Packard, 1871) based on egg morphology, this species egg distinctly differs from E. texana by the number of lateral grooves and by the single domed end.

Spinicaudata Catalogus (Crustacea: Branchiopoda).

The Spinicaudata (spiny clam shrimp) are a large group of freshwater, bivalved branchiopod crustaceans in need of taxonomic revision. Herein, the extant Spinicaudata families and genera are defined and diagnosed according to modern standards. An annotated catalogue of the Spinicaudata taxa is presented with synonyms. More than 747 spinicaudatan taxa are presented, of which 215 are considered valid families, genera and species. Chresonyms are provided for taxa redescribed according to modern standards. It is hoped that this catalogue will provide a basis for further taxonomic revision and phylogenetic work within the Spinicaudata.

The World's First Clam Shrimp Symposium: Drawing Paleontology and Biology Together.

After a symposium and special issue devoted to the study of clam shrimp, it is tempting to ask what is next... where is the study of clam shrimp going? Rather than try to read the tea leaves to predict the future, we will instead offer some closing thoughts on where the study of clam shrimp should go and what areas are ripe for investigation. Many of these ideas integrate both fossil and modern clam shrimp to get at a more complete view of their evolution and ecology.

Molecular Evaluation of the Fairy Shrimp Family Branchinectidae (Crustacea: Anostraca) Supports Peripatric Speciation and Complex Divergence Patterns.

The Branchinectidae is a diverse and widely distributed group of anostracans. The majority of work on the group has focused on the morphological delineation of taxa and biogeography. Here we present a molecular phylogeny for select members of the family to better understand the distribution of morphological variation among species, and test biogeographic models of speciation for the group. Although we conducted both molecular and morphological phylogenies for the Branchinectidae, the morphological analysis did not support our molecular phylogeny and it did not support previous species group concepts based on geography. Our molecular phylogenetic analysis suggests that the family may have originated in Eurasia and found support for numerous species groups. These phylogenetic groups assisted in delineating species groups that are all definable morphologically and/or ecologically. The peripatric speciation model was supported from our analysis, offering credence to previously published speciation models in anostracans. This suggests that these processes may be important in other Branchiopoda and should be rigorously evaluated when delineating species.