<Emphasis Type="Italic">Prorocentrum rivalis</Emphasis> sp. nov. (Dinophyceae) and its phylogenetic affinities inferred from analysis of a mixed morphological and LSU rRNA data set

A new freshwater epiphytic Prorocentrum species, Prorocentrum rivalis, from the temperate region of the Haute-Vienne, France, is described. This species is the third freshwater species identified among approximately 60 marine Prorocentrum species. This new species is described using scanning electron microscope and phylogenetic analyses by a polyphasic approach (LSU rRNA sequences combined with 9 morphological characters). The phylogenetic analysis attests that P. rivalis is close to other planktonic freshwater species and the freshwater Prorocentrum clade is evolutionarily derived from an epiphytic freshwater prorocentroid ancestor. The unique marine species in the freshwater clade results from an ecophysiological reversion. P. rivalis differs from other epiphytic taxa by its rarity, its temperate distribution and its ecophysiological needs. The phylogeny confirms also that all planktonic Prorocentrum species are evolutionarily derived from epiphytic/benthic ancestors.     

Non‐parallel divergence across freshwater and marine three‐spined stickleback Gasterosteus aculeatus populations

This work investigated whether multiple freshwater populations of three‐spined stickleback Gasterosteus aculeatus in different freshwater catchments in the Jutland Peninsula, Denmark, derived from the same marine populations show repeated adaptive responses. A total of 327 G. aculeatus collected at 13 sampling locations were screened for genetic variation using a combination of 70 genes putatively under selection and 26 neutral genes along with a marker linked to the ectodysplasin gene (eda), which is strongly correlated with plate armour morphs in the species. A highly significant genetic differentiation was found that was higher among different freshwater samples than between marine–freshwater samples. Tests for selection between marine and freshwater populations showed a very low degree of parallelism and no single nucleotide polymorphism was detected as outlier in all freshwater–marine pairwise comparisons, including the eda. This suggests that G. aculeatus is not necessarily the prime example of parallel local adaptation suggested in much of the literature and that important exceptions exist (i.e. the Jutland Peninsula). While marine populations in the results described here showed a high phenotype–genotype correlation at eda, a low association was found for most of the freshwater populations. The most extreme case was found in the freshwater Lake Hald where all low‐plated phenotypes were either homozygotes for the allele supposed to be associated with completely plated morphs or heterozygotes, but none were homozygotes for the putative low‐plated allele. Re‐examination of data from seven G. aculeatus studies agrees in showing a high but partial association between phenotype–genotype at eda in G. aculeatus freshwater populations and that mismatches occur everywhere in the European regions studied (higher in some areas, i.e. Denmark). This is independent of the eda marker used.     

Freshwater occurrence of the extinct dolphin Parapontoporia (Cetacea: Lipotidae) from the upper Pliocene nonmarine Tulare Formation of California

The diminutive, extinct longirostrine dolphin Parapontoporia is one of the most abundantly represented late Neogene odontocetes from the eastern North Pacific and is widely known from numerous marine strata of late Miocene and Pliocene age in California, Baja California and possibly Japan. Parapontoporia has been identified as the sister taxon of the recently extinct Chinese river dolphin (Lipotes vexillifer); unlike Lipotes, which exclusively inhabited freshwater, the depositional context of Parapontoporia suggests it was marine. A newly identified petrosal of Parapontoporia sp. was preserved alongside terrestrial vertebrates in the nonmarine Tulare Formation (upper Pliocene to Pleistocene, 2.2–0.6 Ma), California, which was deposited under lacustrine and fluviodeltaic conditions. Abundantly preserved freshwater molluscs and rare marine taxa suggest predominantly freshwater settings with intermittent periods of estuarine conditions. This occurrence of Parapontoporia indicates its presence in the San Joaquin basin after the retreat of the inland sea and suggests that this extinct odontocete may have been freshwater tolerant and an inhabitant of marine and freshwater settings, heralding the exclusively freshwater existence of its Recent sister taxon Lipotes vexillifer.     

Prasiola (Prasiolales,Trebouxiophyceae) in Japan: a survey of freshwater populations and new records of marine taxa

Recent collections from marine and freshwater locations have enabled the investigation of diversity of Prasiola in Japan. Sequence data from the rbc L and tuf A markers revealed the presence of three marine species and one freshwater species. Prasiola delicata was confirmed to occur on Daikokujima, Prasiola calophylla was found for the first time in Japan from Hokkaido, and a species within the P. meridionalis/linearis/stipitata complex was found on both Hokkaido and Daikokujima. Collections from a range of populations of freshwater Prasiola, identified here as P. japonica, were found to be conspecific and identical in rbc L and tuf A sequences to freshwater collections from Nepal, Korea, and China.     

Renewed sampling of inland aquatic habitats in southern Africa yields two novel freshwater crab species (Decapoda: Potamonautidae: Potamonautes)

A recent survey of the freshwater streams of the Mecula and Yao mountains in the Niassa province of Mozambique resulted in the discovery of a new freshwater crab species. This species is genetically and morphologically distinct from described species from Mozambique or its neighbouring countries, and is described as P otamonautes bellarussus sp. nov. In addition, a new semi‐terrestrial burrowing freshwater crab P otamonautes flavusjo sp. nov. from the Highveld of the Mpumalanga province in South Africa is described based on unique genetic and morphological characters. The phylogenetic affinities of the two new species in relation to the described eastern and southern African Potamonautes species is determined and the biogeographic implications are discussed. © 2014 The Linnean Society of London     

Geographic variation in otolith morphology among freshwater populations of Aphanius dispar (Teleostei,Cyprinodontiformes) from the southeastern Arabian Peninsula

Aphanius Nardo is a large genus of teleost fishes in the Old World, with 19 described species. Several of these species have only recently been recognized and additional species can be expected from isolated populations in remote areas. We show here that otolith morphology and statistical analyses of otolith variables can contribute to the detection of genetic differentiation in Aphanius. We studied samples of eight Aphanius dispar populations from the southeastern part of the Arabian Peninsula. Two populations originate from freshwater habitats far inland and probably have been isolated since the late Holocene some 4,000 years ago, three populations come from freshwater habitats with occasional connections to the sea, one population originates from a coastal site, and two were artificially introduced populations. The coastal population is interpreted as possessing the basic otolith type of A. dispar. The basic otolith type also occurs in fishes from the freshwater habitat which is located closest to the coast. Otoliths from the two other freshwater populations with occasional connections to the coast differ slightly from the basic type. However, the two populations from the long‐term isolated freshwater habitats far inland show distinct morphological changes. Our results are consistent with the hypotheses that i) otolith morphology is primarily genetically determined and is little influenced by physical parameters of the habitat, and ii) isolated A. dispar populations may be capable of evolving into new species within short periods of time. J. Morphol., 2009. © 2008 Wiley‐Liss, Inc.     

Freshwater snails of Oman,South Eastern Arabia

A systematic account is given of the extant freshwater snail fauna of Oman, based on recent collections made in Dhofar and in the northern mountainous areas. Also included are certain species found in brackish coastal localities. A total of 8 freshwater species is regarded as belonging to the fauna of normal freshwater; 7 have been found alive (Thiara scabra, Melanoides tuberculata, Lymnaea natalensis, Gyraulus piscinarum, Biomphalaria arabica, Bulinus wrighti and Indoplanorbis exustus) and one is known only as shells (Paludestrina glaucovirens). This report of G. piscinarum is the first for Oman and may be the first reliable identification for Arabia. Three taxa from brackish water, Gangetia miliacea, Iravadia quadrasi and Melanoides sp., are new for the fauna of Oman and of the whole Arabian peninsula. The finding of G. miliacea provides the first instance of any member of the Stenothyridae living west of the Gulf of Oman and identified from whole snails rather than empty shells. I. quadrasi is the first member of its genus to be found alive west of the Gulf of Oman.     

A new species of <Emphasis Type="Italic">Dermoergasilus</Emphasis> Ho &; Do, 1982 (Copepoda: Ergasilidae) from freshwater fishes in the south-west of Western Australia

A new species of Dermoergasilus Ho & Do, 1982 is described from freshwater fish hosts in the south west of Western Australia. D. occidentalis n. sp. differs from previously described species in the genus principally by the armature of the legs. The new species was found on the gills of the freshwater cobbler Tandanus bostocki Whitely and western minnow Galaxias occidentalis Ogilby in two different river systems.     

Atmospheric transport of freshwater algae Pediastrum in the American Southwest

A single colony of the freshwater green algae Pediastrum boryanum boryanum was observed in a 1994 Tauber trap north of Santa Fe, New Mexico, USA. The rate of deposition for the colony is low, 0.8 per square centimeter per year. The likely source of the freshwater algae is Cochiti Lake reservoir 42 km southwest of the Tauber pollen collector. The ability of Pediastrum to be dispersed in the atmosphere and to survive desiccation gives the freshwater algae a unique biogeographic capability of rapid dispersal and colonization independent of streams and aquatic birds.     

Freshwater crayfish invasions in South Africa: past,present and potential future

Freshwater crayfish invasions have been studied around the world, but less so in Africa, a continent devoid of native freshwater crayfish. The present study reviews historical and current information on alien freshwater crayfish species introduced into South Africa and aims to indicate which areas are at risk from invasion. As is the case elsewhere, South Africans have shown a keen interest in both farming and keeping freshwater crayfish as pets, which has resulted in Cherax cainii, Cherax destructor, Cherax quadricarinatus and Procambarus clarkii being introduced to the country. There is evidence of successful establishment in the wild for C. quadricarinatus and P. clarkii in different parts of the country. Species distribution models suggest that the eastern part of the country and parts of the Eastern and Western Cape are at higher risk of invasion. At present, illegal translocations represent the most likely pathway of crayfish spread in South Africa. A continued risk of invasion by freshwater crayfish species in South Africa is highlighted, which reinforces the need for more research, as well as for strong mitigation measures, such as stronger policing of existing regulations, management or eradication where feasible and public education.     

The generaAniptodera, Halosarpheia, Nais andPhaeonectriella from freshwater habitats

The generic concepts inAniptodera, Halosarpheia, Nais andPhaeonectriella are discussed and those species occurring in freshwater are described, some with illustrations. Five new species:Aniptodera lignicola, A. mauritaniensis, A. megalospora, A. palmicola, Phaeonectriella appendiculata are also described. A key to the freshwater species in the above genera and a synoptic diagram of their ascospores are provided.     

The freshwater medusae of the world – a taxonomic and systematic literature study with some remarks on other inland water jellyfish

Several medusa species have been described from inland waters in Australia, Eurasia, Africa and America. The chief objective of this study is to summarize all species described from freshwater and from saline lakes, because the knowledge about this group is sparse and scattered in the literature. I summarize all accessible literature to deduct how many species of freshwater medusae exist and to show their distribution, relation and their phylogenetic origin.All medusae described from freshwater except Halmomises are Olindiidae (Limnomedusae). More than 20 Olindiidae species (in 6 genera) have been recorded from freshwater. However, about half of them may not be valid species or have been described insufficiently or improperly. Within the genera Craspedacusta only 3 (or 5) species are certain (C. sowerbii, C. iseanum, C. sinensis (and maybe C. sichuanensis and C. ziguiensis)). The genera Limnocnida may consist of 6 species, three from Africa (L. tanganjicae, L. victoriae, L. congoensis) and 3 from India (L. indica, L. biharensis, L. nepalensis). The status of Astrohydra (from Japan), Mansariella and Keralika (both from India) is uncertain. Additionally, the present study suggests that Craspedacusta and at least one type of Calpasoma hydrants are identical and Astrohydra may be closely related to Craspedacusta and/or Calpasoma.A comparison of the freshwater medusae with species described from saline lakes and brackish sites (Australomedusae from Australia and Moerisia from Egypt, Black Sea, Caspian Sea and Ganges Estuary) shows that these two groups are not closely related.     

Surgical implantation of radio tags in three eel species (Anguilla spp.) in South Africa

Studies have reported poor survival of surgically tagged freshwater fishes in warm African waters. This study aimed to assess the applicability of using radio telemetry (and surgical implantation of tags) for Anguilla spp. Nineteen yellow eels (Anguilla bengalensis, A. marmorata and A. mossambica) were surgically implanted with radio tags between October 2018 and January 2019 in the Thukela River, South Africa. Most eels were alive 6 months after tagging, and recaptured eels displayed advanced or complete healing at the incision site. Therefore, this method appears suitable for African freshwater eels.     

Gamete interaction in the white sturgeon Acipenser transmontanus: a morphological and physiological review

Synopsis Sturgeon gametes differ from those of most fish in that the sperm possess acrosomes that undergo exocytosis and filament formation while the eggs possess numerous micropyles. Acipenser transmontanus eggs are encased by multilayered envelopes that consist of outer adhesive jelly coats and three structured layers interior to the jelly. The glycoprotein jelly layer only becomes adhesive upon exposure to freshwater. The layer interior to the jelly, layer 3, is the other carbohydrate-containing component of the egg envelope. This layer consists of a water-insoluble glycoprotein that, upon freshwater exposure, is hydrolyzed by a trypsinlike protease to yield a water-soluble, lower molecular weight carbohydrate-containing component. This component can be identified in the surrounding medium when unfertilized eggs are incubated in freshwater. This egg water component elicits acrosome reactions only in homologous sperm. The A. transmontanus sperm acrosome reaction is a Ca⁺⁺ and/or Mg⁺⁺ dependent event that includes the formation of a 10 μ long fertilization filament. A. transmontanus fertilization can occur at low sperm per egg ratios; however, crossfertilization of A. transmontanus eggs with lake sturgeon, A. fluvescens, sperm results in a very low number of fertilized eggs, even at high sperm per egg ratios. The morphological, physiological, and biochemical phenomenon reviewed in this paper are related to the environment in which they occur. Also, the possible role of the acrosome and the presence of numerous micropyles are discussed.     

A new genus and species of freshwater monostiliferous hoplonemertean (Nemertea, Enopla) from the People's Republic of China

A new genus and species of freshwater monostiliferous hoplonemertean, Limnemertes poyangensis gen. et sp. nov., from Poyang Lake, People's Republic of China, is described and illustrated. The taxon is compared and contrasted with previously described freshwater hoplonemerteans. This is the fourth species of freshwater nemertean to be described from China and the first recorded from Poyang Lake.     

Phylogenetic analysis of Spiroplasmas from three freshwater crustaceans (Eriocheir sinensis, Procambarus clarkia and Penaeus vannamei) in China

Disease epizootics in freshwater culture crustaceans (crab, crayfish and shrimp) gained high attention recently in China, due to intensive developments of freshwater aquacultures. Spiroplasma was identified as a lethal pathogen of the above three freshwater crustaceans in previous studies. Further characterization of these freshwater crustacean Spiroplasma strains were analyzed in the current study. Phylogenetic position was investigated by analysis of partial nucleotide sequences of 16S ribosomal RNA (rRNA), gyrB and rpoB genes, together with complete sequencing of 23S rRNA gene and 16S–23S rRNA intergenetic spacer regions (ISRs). Phylogenetic analysis of these sequences showed that the above-mentioned three freshwater crustacean Spiroplasma strains were identical and had a close relationship with Spiroplasma mirum. Furthermore, the genomic size, serological studies and experimental infection characteristics confirmed that three freshwater crustacean Spiroplasma strains are a single species other than traditional S. mirum. Therefore, these data suggest that a single species of Spiroplasma infects all three investigated freshwater crustaceans in China, and is a potential candidate for a new species within the Spiroplasma genus. These results provide critical information for the further investigations in fresh aquaculture epizootics related to tremor diseases, caused by this infectious agent.     

Tracking the history of an invasion: the freshwater croakers (Teleostei: Sciaenidae) in South America

In this study, the competing hypotheses of single vs. double colonisation events for freshwater Pachyurinae (Sciaenidae) in South America is tested and the historical biogeography of the expansion of this clade within the continent is reconstructed based on phylogenetic analysis. Parsimony and Bayesian inference (BI) for 19 marine and freshwater species assigned to Sciaenidae, Haemulidae and Polypteridae were determined based on partial sequences of the mitochondrial 16S and cytochrome b genes and fragments of the nuclear Tmo‐4C4 and rhodopsin genes. A parsimonious ancestral character reconstruction of euryhalinity was performed on a clade of families of closely related fishes to evaluate the role of ecological fitting in the colonisation of freshwater by a marine sciaenid. The parsimony and BI phylogenetic hypotheses for the concatenated sequences supported the monophyly of the freshwater Sciaenidae. Divergence of the two freshwater clades of Sciaenidae, Pachyurinae and Plagioscion, occurred within the Amazon Basin. Within Pachyurinae, two clades were recovered: one composed of species from the Amazon and the Paraná Basin and a second with representatives from the São Francisco and south‐eastern Atlantic basins. The results were compatible with the hypothesis of a single colonisation event of South American freshwater habitats by a marine lineage. The hypothesis of gradual adaptation to freshwater was rejected in favour of the hypothesis of ecological fitting. Sciaenidae, or a subordinate lineage within the family, is ancestrally capable of withstanding exposure to low‐salinity habitats, which putatively facilitated the colonisation of freshwater habitats. The subsequent diversification and expansion of Pachyurinae across South America followed this colonisation and replicated the general pattern of the area relationships of South American river basins for several other fish groups.