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Temporary lentic water bodies host biotic assemblages adapted to the transient nature of these freshwater habitats. Fairy shrimps (Crustacea, Branchiopoda, Anostraca) are one of the most important biological components of these unique environments and have a fossil record dating back to the Middle Jurassic (>150 million years). Some anostracan species show a geographically restricted distribution, whereas others are widely dispersed. We aimed to investigate the relationship between different geographic extents and patterns of genetic structure in species of Anostraca. Following this objective, we selected two species with contrasting ranges but overlapping geographic distributions and similar life-history traits in the study area. We analysed additional information that, from an ecological (e.g. egg-bank, niche breadth, and pond connectivity) and evolutionary (e.g. crown-group age of each species) perspective, may explain the obtained phylogeographic patterns. Between 2005 and 2018, we sampled two species of fairy shrimps (309 specimens of Branchipus cortesi and 264 specimens of Tanymastix stagnalis) from 53 temporary ponds of Portugal. We added five other locations from Spain and France to include other European locations for T. stagnalis. Additionally, we also sampled Branchipus schaefferi from two temporary water bodies (Spain and Morocco) to include in the dating analysis. Reconstructed phylogenies based on mitochondrial sequence data indicate the existence of deeply divergent clades with an unequivocal phylogeographic structure in T. stagnalis and shallower divergences in B. cortesi with a less clear geographic correspondence. We found evidence of frequent local and rare long-distance dispersal events in both species and limited intermediate dispersal, which was more common in B. cortesi. A Bayesian dating analysis using the Branchiopoda fossil record estimated the age of the most recent common ancestors of T. stagnalis and B. cortesi at 32.4 and 12.8 million years, respectively. Haplotype accumulation curves indicated that only a portion of the genetic composition of the species was sampled on each hydroperiod and showed the existence of large, genetically diverse egg banks that remain in the soil. These egg banks represent a genetic reservoir that guarantees the survival of the species because active populations from different hydroperiods may be genetically different and adapt to a changing environment. We hypothesise that the contrasting phylogeographic patterns displayed by the two fairy shrimp species may result from: (1) the earlier age of the most recent common ancestor of T. stagnalis, as older species have more time to accumulate mutations and, thus, are expected to exhibit higher genetic differentiation among populations; (2) slight differences in adult behaviour, life-history traits and cyst morphologies of T. stagnalis and B. cortesi favouring different animal dispersal vectors with distinct dispersal abilities. Therefore, phylogeographic patterns may be explained by both evolutionary and ecological processes, which operate in different time scales. UIDB/04326/2020; UID/MAR/04292/2019; EMBRC.PT ALG-01-0145-FEDER-022121; BIODATA.PT ALG-01-0145-FEDER-022231; DL 57/2016/CP1361/CT0013 info:eu-repo/semantics/publishedVersion

nostraca are known by their ability for long-distance dispersal, but the existence in several spe-cies of deep, geographically structured mtDNA lineages suggests their populations are subjectedto allopatric differentiation, isolation, and prevalence of local scale dispersion.Tanymastix stagna-lisis one of the most widespread species of Anostraca and previous studies revealed an uncleargeographical pattern of mtDNA genetic diversity. Here, we analyze populations from the Iberianand Italian Peninsulas, Central Europe, and Scandinavia, with the aim to characterize the patternsof genetic diversity in a spatio-temporal framework using mtDNA and nuclear markers to test geneflow among close populations. For these aims we built a time-calibrated phylogeny and carried outBayesian phylogeographic analyses using a continuous diffusion model. Our results indicated thatT. stagnalispresents a deeply structured genetic diversity, including 7 ancient lineages, some ofthem even predating the Pleistocene. The Iberian Peninsula harbors high diversity of lineages, withstrong isolation and recent absence of gene flow between populations. Dispersal at local scaleseems to be the prevailing dispersal mode ofT. stagnalis, which exhibits a pattern of isolation-by-distance in the Iberian Peninsula. We remark the vulnerability of most of these lineages, giventhe limited known geographic distribution of some of them, and the high risk of losing importantevolutionary potential for the species., This work was supported by the Project Grant CGL2015-66571-P (MINECO/FEDER) of Spain.

In the present study we applied a discriminant function analysis to distinguish two fairy shrimp species, Branchipus schaefferi and Tanymastix stagnalis (Anostraca), co-occurring in Lago dell’Orso in central Italy. Our aim was to obtain information on the pattern of coexistence of these two species to investigate their syntopy since early larval stages. To identify the larvae of the two species we used six discriminant functions, one for each larval stage considered (nauplius, four metanauplius stages and juvenis), and based on morphometric analyses and measurements of different traits (thoracic appendages, body length, length of first antenna, length of head, thorax length and length of furca). The pool was visited at weekly intervals during two time periods for a total of 4 years (1995–1996 and 2000–2001) and physical and chemical variables (water level, water and air temperature, pH and conductivity) were recorded. A total of 1067 specimens were collected, measured and morphometrically identified. B. schaefferi was more abundant and persistent than T. stagnalis. At any stage, T. stagnalis was bigger than B. schaefferi and this difference may justify niche differentiation between coexisting species. Difference in size might be linked to difference in life-span as B. schaefferi reproduced earlier and at a smaller size than T. stagnalis. When the hydroperiod is short, B. schaefferi might be the only species to produce resting eggs in time for reproduction. On the other hand, T. stagnalis may have an advantage in the longest hydroperiods. In an ephemeral seasonal pond such as Lago dell’Orso, coexistence can be fostered and competitive exclusion can be prevented as a result of seasonal environmental changes.

Malladas de El Saler is a mosaic of dune slacks scattered along a coastal sand bar in the Mediterranean region. Active populations of the fairy shrimp T. stagnalis are exclusively present in one of these ponds. We combined field observations and laboratory experiments to find the ecological requirements of T. stagnalis that determine this habitat exclusiveness and the possibility of future establishment in nearby ponds. Conductivity revealed as a determinant ecological constraint. In the field, the species was restricted to conductivity levels below 1.28 mS cm−1 and in experimental microcosms, hatchability, survival and reproductive potential were detrimental from 2.9 mS cm−1. The observation of life history characteristics from the experimental individuals confirmed the importance of the unpredictable character of Mediterranean temporary ponds in shaping life history strategies, as they hatched early, matured rapidly and produced a high number of cysts. We discuss the essential steps during colonization that may explain the presence or absence in our ponds, and revealed a harsh future for the species if the current conditions of habitat deterioration persist. We suggest several conservation measures, including a cyst bank storage or/and adult translocations to nearby suitable ponds. These measures will ensure (1) the preservation of genetic diversity and (2) healthy metapopulation dynamics with recolonization rates compensating for local extinctions.

Summary 1. To monitor the diversity and distribution patterns of large branchiopods and the effects of local and regional processes, 30 temporary wetlands in a nature reserve in the Camargue (southern France) were sampled and characterised during three consecutive inundations (2005–08). Additional species were added to the list for each wetland by hatching animals from the resting egg bank, after determining the optimal hatching conditions. 2. A total of five species were found, representing 28% of the species known in France and 56% of the known Camargue species. Tanymastix stagnalis, Branchipus schaefferi, Chirocephalus diaphanus (Anostraca), Triops cancriformis (Notostraca) and Imnadia yeyetta (Spinicaudata) were distributed over a total of 19 wetlands. 3. More than one species was present in 79% of the wetlands containing large branchiopods. Individual wetlands harboured on average 2.8 species, with a maximum of five coexisting species. Large branchiopod assemblages were temporally variable, differing among the three inundations with different climatological conditions. 4. The most important habitat factor influencing the distribution of large branchiopods was salinity, adversely affecting the density and survival of hatchlings. The persistence of large branchiopods in these temporary waters may be threatened by increasing salinisation driven by intensive water management and climate change.

The shape of the resting eggs of a large branchiopod crustacean, the Anostraca Tanymastix stagnalis, is represented very accurately by analytical expressions. The occurrence of atypical shape of some T. stagnalis eggs may be viewed as a simple change of the analytical expression describing the usual egg shape. Their unusual shape may be explained by a higher embryo volume within an envelope of a given size. Biological implications are briefly discussed and hypothesized in an evolutionary point of view. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society, 2007, 90, 55–60.

Between 1995 and 1999, we surveyed the large branchiopods (Crustacea, Branchiopoda) of Numidia, the coastal plain of northeastern Algeria. Samples from ca 100 sites yielded two species of Anostraca (Chirocephalus diaphanus, new to Numidia, and Tanymastix stagnalis), one notostracan (Lepidurus apus lubbocki) and one spinicaudatan (Cyzicus tetracerus). The absence of Streptocephalus torvicornis buchetiis noteworthy. An annotated check-list of all large branchiopods known from Algeria is also presented and discussed. Several species appear to be in danger of extinction.

In this note recent records of some Anostraca species in Italy are presented. These data widen the known distribution in Italy of Branchipus schaefferi Fischer, 1834, Tanymastix stagnalis Linnaeus, 1758, Chirocephalus ruffoi Cottarelli & Mura, 1984 and Branchinella spinosa Milne-Edwards, 1840, and illustrate the problem of inadequate knowledge of our territory, at least as far as Anostraca (Branchiopoda) are concerned.

Distribution, phenology and status is given for the five Danish species of larger Branchiopoda. All species are univoltine and inhabit small, temporary waterbodies. The distribution of all species is very restricted in Denmark, probably because of habitat destruction.

The early observation from 1914 of Tanymastix stagnalis in Norway was not repeated recently, showing a rare and restricted distribution of this species. All four sampled localities were concentrated in the same area of the Trollheimen Mountains with altitudes of 900–1244 m above sea level. In March 2002, a new population of T. stagnalis was observed at about 50 km north of Madrid at an altitude of 1350 m. In general, all habitats with T. stagnalis were fishless shallow ponds and varied in size from 1 to about 300 m2. Natural variability of the global temperature is well accepted, but recent climate models have predicted increases in global average temperature. Based on the new biogeographical distribution, diurnal temperature variations, and biological evidence (inference with the analysis of mitochondria DNA), the immigration history of T. stagnalis was considered on the basis of two opposing immigration theories and in relation to the implications of global climate change. Two immigration theories, namely – the Tabula rasa and Nunatak, have prevailed in explaining the present distribution of plants and animals in Scandinavia. It was concluded that the rare occurrence of T. stagnalis in Norway fits into the Nunatak theory and that the species probably survived, at least, the last glaciation on Nunataks or coast refuges located in central northwestern Norway at Møre mountain and coast areas. © 2013 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd. This is an open access article under the terms of the Creative Commons Attribution License

The ‘Large Branchiopod’ fauna of Europe consists of 72 species and sub-species: 50 anostracans, 8 notostracans, 12 spinicaudatans, and 2 laevicaudatans. Their geographical distribution is mapped, and remarks on ecological requirements of species are given.

[Le prime osservazioni compiute al microscopio elettronico a scansione sulla morfologia delle uova resistenti di Crostacei Anostraci (Gilchrist, 1978; Mura et al., 1978) hanno indotto un numero sempre crescente di studiosi ad usare tale carattere, anche in combinazione con le dimensioni delle uova stesse, quale mezzo di identificazione della specie (Alonso & Alcaraz, 1984; Munuswamy et al., 1985; Mura & Thierry, 1986; Hamer, unpubl.). Successivi approfonditi studi sull'argomento (Mura, 1986), hanno evidenziato, almeno per le specie italiane, una elevata variabilita intraspecifica mettendo quindi in discussione la validita del carattere sopra citato, dal punto di vista tassonomico. Il presenta lavoro si propone di esaminare in dettaglio gli aspetti del problema e di fare il punto sulla situazione, alla luce di ulteriori studi compiuti su popolazioni italiane del genere Chirocephalus., Le prime osservazioni compiute al microscopio elettronico a scansione sulla morfologia delle uova resistenti di Crostacei Anostraci (Gilchrist, 1978; Mura et al., 1978) hanno indotto un numero sempre crescente di studiosi ad usare tale carattere, anche in combinazione con le dimensioni delle uova stesse, quale mezzo di identificazione della specie (Alonso & Alcaraz, 1984; Munuswamy et al., 1985; Mura & Thierry, 1986; Hamer, unpubl.). Successivi approfonditi studi sull'argomento (Mura, 1986), hanno evidenziato, almeno per le specie italiane, una elevata variabilita intraspecifica mettendo quindi in discussione la validita del carattere sopra citato, dal punto di vista tassonomico. Il presenta lavoro si propone di esaminare in dettaglio gli aspetti del problema e di fare il punto sulla situazione, alla luce di ulteriori studi compiuti su popolazioni italiane del genere Chirocephalus.]

1. 1|The conditions for the highest hatching of the resting eggs were found to be at temperatures between 10 and 15°C and in the presence of soil. Prior desiccation was found not to be essential for hatching. 2. 2|Hatching is steadily reduced following periods of desiccation ranging from 1 to 12 months. 3. 3|Eggs hatch following each of at least four periods of wetting and drying. 4. 4|There is a great range in hatching of undesiccated eggs and it is suggested that this could be explained by variations in the thickness of the egg shell layers. 5. 5| Chlorella did not appear to have an inhibitory effect on hatching. 6. 6|There were some indications that changing temperatures may stimulate hatching.

Knowledge of the Branchiopoda of Corsica is limited. Their distribution is updated, on the basis of eight years of investigations on 20 ponds. To date, three species of Anostraca and one species of Notostraca have been reported (Tanymastix stagnalis, Chirocephalus salinus, Branchipus schaefferi and Triops cancriformis cancriformis). B. schaefferi (recorded for the first time in Corsica) occurs in a single locality, C. salinus and T. cancriformis cancriformis are limited to restricted distributions, while T. stagnalis is common in temporary ponds of Corsica. Their status is assessed according to IUCN Red List criteria. Temporary habitats are endangered by human activities and require a proper conservation management.

Patterns of sequence divergence in about 1 kb of mitochondrial DNA coding for two genes (16s rRNA and cytochrome oxidase I, COI) were analysed in 13 populations of the fairy shrimp Tanymastix stagnalis from Norway, Germany, France, Italy (northern and central Italy plus insular populations from Sardinia and the Tuscan Archipelago) and Spain, and in one presumed population of Tanymastix stellae from Corsica. The latter species was originally known only from a single locality in Sardinia, which has been destroyed by urbanization; the Corsican population was referred to T. stellae by some French authors on the basis of the collection of several cysts from mud. mtDNA data revealed a very low level of genetic divergence between the presumed population of T. stellae and the other T. stagnalis populations included in the study. Our genetic findings do not support the presence of T. stellae in Corsica and are in line with previous SEM studies revealing that all species belonging to the genus Tanymastix produce cysts with identical morphology. The results indicate complex phylogeographic relationships and pronounced genetic differentiation among T. stagnalis populations. The islands of Corsica and Sardinia on the one hand and the island of Capraia (Tuscan Archipelago) on the other were probably colonized independently at different times. Genetic relationships among continental populations do not follow a clear geographical trend, indicating that geographical distance is not the main force shaping the pattern of genetic structuring of the species. Stochastic factors such as multiple and independent founder events probably contributed to the striking pattern of genetic differentiation along with subsequent local adaptation. These results agree with previously published molecular work on several groups of aquatic organisms and further support the high potential for dispersal–low gene flow paradox shown by a large array of animals living in lentic habitats.

In Austria, the distribution of Anostraca, Notostraca, and Conchostraca is mainly confined to the flood plains of the rivers Morava and Danube, and the shallow alkaline pans of the Seewinkel region in Burgenland province. Occasionally, large branchiopods can also be found in rain pools of the eastern and central Austrian lowlands, where topography and climate favour the existence of astatic water bodies. Differences in hydrology, temperature and water chemistry requirements may be reflected in local species compositions and species seasonal appearance. A survey conducted from 1994 through 1996 found that Chirocephalus shadini, Eubranchipus grubii, and Lepidurus apus occurred in late winter and spring, while Branchinectaferox,Branchinecta orientatis, Cyzicus tetracerus and Chirocephalus carnuntanus were found exclusively in spring. Streptocephalus torvicornis, Tanymastix stagnalis,and Eoleptestheria ticinensis were present in spring and summer. Branchipus schaefferi was found in summer and fall, whereas Imnadia yeyetta, Leptestheria dahalacensis, Limnadia lenticularis, and Triops cancriformis occurred throughout spring, summer and fall. Streptocephalus torvicornis was documented for Austria for the first time since 1965.

The genus Tanymastix Simon, 1886 is represented in Macedonia by two species: Tanymastix stagnalis (Linnaeus, 1758) and Tanymastix motasi Orghidan, 1945. The fairy shrimp T. stagnalis has been found exclusively in the rock pools containing only several litres of water, above the village of Stracin, N. E. Macedonia. T. motasi is present only in the shallow rainpools, less than 15 cm in depth, scattered over an area of untilled, highly-mineralized pasture land in the Pelagonia Plain, S. W. Macedonia. Both Tanymastix species are the only anostracans in their biotopes.

Life histories of two coexisting Anostracan species, inhabiting a group of mountain ponds in Latium (Pantani di Forca Canapine) are described and discussed, with particular regard to hatching requirements, growth rate, fecundity and life span.

Tanymastix stagnalis is known from seven locations in Ireland. These range from small to large temporary water bodies. It was earlier shown that the best hatching and survival of eggs and young stages occurred in the presence of soil and at temperatures between about 10° and 15°. Some eggs hatched after one drying period, others after up to at least 4 drying and wetting periods. It was found from field observations that the habitat appeared after a minimum of 200 mm of rain in a 2-month period. This occurred on average more than once per year, mostly between June and February. A computer model was constructed using field data, and meteorological data (rainfall and temperature) covering 100 years, to decide how secure the organism was in two contrasting habitats. This showed that in both habitats there was little likelihood of extinction from metorological causes. There was, however, the possibility of destruction of the smaller habitats either through drainage or conversion to permanent ponds through compaction of the soil by heavy farm animals. The distribution and the possibility of harvesting the organisms is briefly discussed.

The main duration of time from egg hatching to egg laying (D) in this anostracan crustacean increases at lower constant temperatures. The mean number of eggs per female lay between 25 and 50. In both regularly changing temperature experiments D was significantly increased (P