New hyalellids (Crustacea, Amphipoda, Hyalellidae) from Lake Titicaca

Two new species of hyalellid amphipods, Hyalella crawfordi and H. gauthieri, are described from Lake Titicaca; H. echinus (Faxon, 1876) is redescribed. The H. echinus group of species is newly proposed for these three species, and a group diagnosis is provided. A key to the three species in the group is provided Full article published online at http://www.senckenberg.de/odes/06-10.htm.     

Description of Thecavermiculatus andinus n.sp. (Meloidoderidae), a Round Cystoid Nematode from the Andes Mountains of Peru

Thecavermiculatus andinus n.sp. is described and illustrated from Oxalis tuberosa originally collected in the vicinity of Lake Titicaca high in the Andes mountains of southern Peru. This new species differs markedly front the other two species in the genus, especially in having a much greater female vulval-anal distance and annules with lined punctation on most of the female body with a lacelike pattern restricted to the posterior portion, particularly at the vulva and anus which do not protrude. Females are essentially spherical with protruding neck, white to yellowish in color, and can easily be mistaken for potato cyst nematodes. Among the dozen or more known weed and crop host plants are potato and eggplant. In order to accommodate this new species, the genus Thecavermieulatus is emended. A key to the species of this genus is presented.     

Four new species of Gomphocythere (Crustacea, Ostracoda) from Lake Tanganyika, East Africa

Four new species of the ostracod genus Gomphocythere are described from Lake Tanganyika (East Africa): Gomphocythere downingi n. sp. G. coheni n. sp., G. wilsoni n. sp., and G. woutersi n. sp. All species are endemic to the lake and are found within a variety of substrates and depths. The addition of these four new species brings the total number of endemic Gomphocythere species in Lake Tanganyika to nine. Other Gomphocythere species are known from water bodies throughout East and South Africa and in the Levant. Brooding is an important, but not a unique, preadaptation for the persistence and taxic prolific speciation of this lineage in Lake Tanganyika.     

Experimental infection of the digeneans to some congeneric snail species radiated in a single water system: Relative importance of local evolution and phylogenetic constraint

To determine the relative importance of local adaptation caused by host–parasite coevolution and resource tracking by the parasites, the susceptibility of the freshwater snail genus Semisulcospira to the digenean parasite genus Genarchopsis was investigated experimentally. Four snail species endemic to the Lake Biwa system in Japan and two non-endemic species were investigated. All but one species was also tested for local variation in susceptibility.Parasites were obtained from Takashima (mix population of Genarchopsis gigi and Genarchopsis chubuensis) and Nagahama (G. chubuensis). In endemic Semisulcospira, closely related specie pairs (Semisulcospira habei and Semisulcospira niponica, Semisulcospira decipiens and Semisulcospira nakasekoae) showed similar susceptibilities to parasites from both localities. S. habei and S. niponica were highly susceptible to parasites from Takashima, but were resistant to parasites from Nagahama. S. decipiens and S. nakasekoae showed moderate susceptibility to parasites from both localities. None of the endemic snail species showed a clear local variation in susceptibility. These results show that the susceptibility of endemic Semisulcospira to Genarchopsis is conservative and can be regarded as an example of resource-tracking. One of the non-endemic snails, Semisulcospira libertina, showed local variation in susceptibility. This variation was not related to the sympatry of the parasites used for the experimental infection, suggesting that it was not the result of local adaptation by parasites.     

Global diversity of amphipods (Amphipoda; Crustacea) in freshwater

Amphipods are brooding peracaridan crustaceans whose young undergo direct development, with no independent larval dispersal stage. Most species are epibenthic, benthic, or subterranean. There are some 1,870 amphipod species and subspecies recognized from fresh or inland waters worldwide at the end of 2005. This accounts for 20% of the total known amphipod diversity. The actual diversity may still be several-fold. Amphipods are most abundant in cool and temperate environments; they are particularly diversified in subterranean environments and in running waters (fragmented habitats), and in temperate ancient lakes, but are notably rare in the tropics. Of the described freshwater taxa 70% are Palearctic, 13% Nearctic, 7% Neotropical, 6% Australasian and 3% Afrotropical. Approximately 45% of the taxa are subterranean; subterranean diversity is highest in the karst landscapes of Central and Southern Europe (e.g., Niphargidae), North America (Crangonyctidae), and Australia (Paramelitidae). The majority of Palearctic epigean amphipods are in the superfamily Gammaroidea, whereas talitroid amphipods (Hyalella) account for all Neotropic and much of the Nearctic epigean fauna. Major concentrations of endemic species diversity occur in Southern Europe, Lake Baikal, the Ponto-Caspian basin, Southern Australia (including Tasmania), and the south-eastern USA. Endemic family diversity is similarly centered in the Western Palearctic and Lake Baikal. Freshwater amphipods are greatly polyphyletic, continental invasions have taken place repeatedly in different time frames and regions of the world. In the recent decades, human mediated invasions of Ponto-Caspian amphipods have had great impacts on European fluvial ecosystems. Guest editors: E. V. Balian, C. Lévêque, H. Segers and K. Martens Freshwater Animal Diversity Assessment     

Accumulation and exchange of parasites during adaptive radiation in an ancient lake

In the ancient Lake Baikal, Russia, amphipod crustaceans have undergone a spectacular adaptive radiation, resulting in a diverse community of species. A survey of microsporidian parasites inhabiting endemic and non-endemic amphipod host species at the margins of Lake Baikal indicates that the endemic amphipods harbour many microsporidian parasite groups associated with amphipods elsewhere in Eurasia. While these parasites may have undergone a degree of adaptive radiation within the lake, there is little evidence of host specificity. Furthermore, a lack of reciprocal monophyly indicates that exchanges of microsporidia between Baikalian and non-Baikalian hosts have occurred frequently in the past and may be ongoing. Conversely, limitations to parasite exchange between Baikalian and non-Baikalian host populations at the margins of the lake are implied by differences in parasite prevalence and lack of shared microsporidian haplotypes between the two host communities. While amphipod hosts have speciated sympatrically within Lake Baikal, the parasites appear instead to have accumulated, moving into the lake from external amphipod populations on multiple occasions to exploit the large and diverse community of endemic amphipods in Lake Baikal.     

The endemic gastropod fauna of Lake Titicaca: correlation between molecular evolution and hydrographic history

Lake Titicaca, situated in the Altiplano high plateau, is the only ancient lake in South America. This 2- to 3-My-old (where My is million years) water body has had a complex history that included at least five major hydrological phases during the Pleistocene. It is generally assumed that these physical events helped shape the evolutionary history of the lake's biota. Herein, we study an endemic species assemblage in Lake Titicaca, composed of members of the microgastropod genus Heleobia, to determine whether the lake has functioned as a reservoir of relic species or the site of local diversification, to evaluate congruence of the regional paleohydrology and the evolutionary history of this assemblage, and to assess whether the geographic distributions of endemic lineages are hierarchical. Our phylogenetic analyses indicate that the Titicaca/Altiplano Heleobia fauna (together with few extralimital taxa) forms a species flock. A molecular clock analysis suggests that the most recent common ancestor (MRCAs) of the Altiplano taxa evolved 0.53 (0.28-0.80) My ago and the MRCAs of the Altiplano taxa and their extralimital sister group 0.92 (0.46-1.52) My ago. The endemic species of Lake Titicaca are younger than the lake itself, implying primarily intralacustrine speciation. Moreover, the timing of evolutionary branching events and the ages of two precursors of Lake Titicaca, lakes Cabana and Ballivián, is congruent. Although Lake Titicaca appears to have been the principal site of speciation for the regional Heleobia fauna, the contemporary spatial patterns of endemism have been masked by immigration and/or emigration events of local riverine taxa, which we attribute to the unstable hydrographic history of the Altiplano. Thus, a hierarchical distribution of endemism is not evident, but instead there is a single genetic break between two regional clades. We also discuss our findings in relation to studies of other regional biota and suggest that salinity tolerance was the most likely limiting factor in the evolution of Altiplano species flocks.     

The recent evolutionary origin of the phenotypically novel amphipod Hyalella montezuma offers an ecological explanation for morphological stasis in a closely allied species complex

Numerous molecular studies have identified morphologically cryptic, freshwater invertebrate species, but have not suggested possible mechanisms for their phenotypic stasis. The amphipod crustacean genus Hyalella contains numerous morphologically cryptic species in the H. azteca complex, as well as a small number of morphologically very divergent, narrowly endemic taxa. One such taxon, Hyalella montezuma, is the sole planktonic filter-feeder within the North American amphipod fauna, and is known only from Montezuma Well, a fishless travertine spring mound in Arizona, USA. In this study, we conduct a phylogenetic analysis of mtDNA sequence data using likelihood, Bayesian and cladistic approaches to determine both the relationship of H. montezuma to the H. 'azteca' species complex, and to ascertain if its morphological and ecological differentiation have been comparatively recent. The results show that H. montezuma has a very close phylogenetic affiliation with one lineage in the H. azteca complex, indicating that its origin has been recent. We present evidence suggesting that fish predation is an important ecological factor, which constrains morphological and ecological diversification within the genus Hyalella, and that Montezuma Well has provided a relaxation on this constraint.     

On the Cyprideis species flock (Crustacea, Ostracoda) in Lake Tanganyika, with the description of four new species

Four new species, belonging to three genera, of ostracods from Lake Tanganyika are described: Mesocyprideis nitida sp.nov., Romecytheridea belone sp.nov., R. plegma sp. nov. and Cyprideis loricata sp. nov. The Cyprideis species flock of Lake Tanganyika now consists of 17 formally described species (16 endemic) in 6 genera (4 endemic). The geographical and ecological distribution of the four species is briefly discussed and some supplementary remarks on the radiation of the Cyprideis species flock in Lake Tanganyika are offered.     

Metacercariae of new trematode species of the genus Diplostomum (Trematoda,Diplostomidae) from fishes of Lake Tana,Ethiopia

Four new species of trematodes of the genus Diplostomum are described from metacercariae found in fishes from Lake Tana in Ethiopia: Diplostomum garrae sp. n. from the lens of Garra dembecha, D. longicollis sp. n. from the lens of Barbus humilis, D. montanum sp. n. from the lens of Barbus humilis, and D. tilapiae sp. n. from the vitreous body of Oreochromis niloticus. The metacercariae of the new species considerably differ in morphology and size from those of all known Holarctic species. It is the first African record of metacercariae of the genus Diplostomum in fish.     

Feeding rates of common Antarctic gammarid amphipods on ecologically important sympatric macroalgae

Single species feeding trials employing both fresh algal tissues and alginate food pellets containing dried finely ground algal tissues were conducted to examine the relative palatability of sympatric Antarctic macroalgae (three brown and five red macroalgal species) to three common herbivorous gammarid amphipods (Prostebbingia gracilis Chevreux, Gondogeneia antarctica (Chevreux) Thurston, and Metaleptamphopus pectinatus Chevreux). In fresh algal tissue bioassays, both the amphipods P. gracilis and G. antarctica consumed significantly greater amounts of the red alga Palmaria decipiens over all other seven species of macroalgae. The amphipod M. pectinatus failed to consume measurable quantities of fresh thalli of any macroalgae and therefore is likely to feed on other resources. In food pellet bioassays, the consumption rates of amphipods fed with eight different species of macroalgae were compared with consumption rates on a highly palatable control green alga. Alginate pellets containing finely ground tissues of P. decipiens were consistently the most palatable of any of the macroalgae to P. gracilis and G. antarctica, while pellets containing the brown algae Desmarestia menziesii, D. anceps and the red alga Plocamium cartilagineum were not consumed by any of the three amphipod species. Regression analysis indicated that feeding rates of the amphipods P. gracilis and G. antarctica on alginate food pellets were not significantly correlated with known species-specific parameters of macroalgal nutritional quality (%N, %C, C:N ratio, soluble protein, soluble carbohydrate, and lipid). Therefore, differences in amphipod macroalgal palatability are most likely related to other factors including physical and/or chemical deterrents.     

Endemism of subterranean Diacyclops in Korea and Japan,with descriptions of seven new species of the languidoides-group and redescriptions of D. brevifurcus Ishida, 2006 and D. suoensis Ito, 1954 (Crustacea,Copepoda, Cyclopoida)

Copepods have been poorly studied in subterranean habitats in Korea. Previous records have indicated mostly the presence of species already described from Japan, with very few endemic elements. This commonality has usually been explained by repeated dispersal across the land bridges that connected the two countries several times during the Pleistocene glacial cycles. However, the Korean Peninsula is known for pockets of Cambrian and Ordovician carbonate rocks, with more than 1,000 caves already having been explored. The relative isolation of these carbonate pockets makes for an enormous speciation potential, and the development of a high level of short-range endemism of subterranean copepods should be expected. Representatives of the genus Diacyclops Kiefer, 1927 are here investigated from a range of subterranean habitats in South Korea, with comparative material sampled from central Honshu in Japan. Morphological analyses of microcharacters, many of which are used in cyclopoid taxonomy for the first time herein, reveal high diversity in both countries. No subterranean species is found in common, although the existence of four sibling species pairs in Korea and Japan may be indicative of relatively recent speciation. We describe seven new stygobiotic species, including three from Korea (Diacyclops hanguk sp. n., Diacyclops leeae sp. n., and Diacyclops parasuoensis sp. n.) and four from Japan (Diacyclops hisuta sp. n., Diacyclops ishidai sp. n., Diacyclops parahanguk sp. n., and Diacyclops pseudosuoensis sp. n.). Diacyclops hanguk, Diacyclops parasuoensis, Diacyclops ishidai, and Diacyclops parahanguk are described from newly collected material, while the other three new species are proposed for specimens previously identified as other, widely distributed species. Diacyclops brevifurcus Ishida, 2006 is redescribed from the holotype female, and Diacyclops suoensis Ito, 1954 is redescribed from material newly collected near the ancient Lake Biwa in Japan. This research provides evidence for the importance of subterranean habitats as reservoirs of biodiversity, and also demonstrates the inadequacy of current morphological methods of identifying closely related species of copepods. The disproportionately high diversity discovered around Lake Biwa provides further evidence in support of the hypothesis about the role of ancient lakes as biodiversity pumps for subterranean habitats. A key to the East Asian species of the languidoides-group is provided.     

Old fossils–young species: evolutionary history of an endemic gastropod assemblage in Lake Malawi

Studies on environmental changes provide important insights into modes of speciation, into the (adaptive) reoccupation of ecological niches and into species turnover. Against this background, we here examine the history of the gastropod genus Lanistes in the African Rift Lake Malawi, guided by four general evolutionary scenarios, and compare it with patterns reported from other endemic Malawian rift taxa. Based on an integrated approach using a mitochondrial DNA phylogeny and a trait-specific molecular clock in combination with insights from the fossil record and palaeoenvironmental data, we demonstrate that the accumulation of extant molecular diversity in the endemic group did not start before approximately 600 000 years ago from a single lineage. Fossils of the genus from the Malawi Rift, however, are over one million years older. We argue that severe drops in the lake level of Lake Malawi in the Pleistocene offer a potential explanation for this pattern. Our results also challenge previously established phylogenetic relationships within the genus by revealing parallel evolution and providing evidence that the endemic Lanistes species are not restricted to the lake proper but are present throughout the Malawi Rift.     

Review of the New Caledonian species of Acritoptila Wells, 1982 (Trichoptera,Insecta), with descriptions of 3 new species

We review the New Caledonian representatives of the Australasian endemic hydroptiline genus Acritoptila, based on examination of a considerable collection of material in the Swedish Museum of Natural History and of types of previously established species. A key for identification of males is given and includes 3 species newly described here: A. parallela sp. n., A. forficata sp. n. and A. macrospina sp. n. For all New Caledonian species, male genitalia are illustrated, and for 5 associated females, distinctive features are illustrated and described.     

Pomphorhynchus patagonicus n. sp. (Acanthocephala: Pomphorhynchidae) from freshwater fishes of Patagonia, Argentina

Pomphorhynchus patagonicus n. sp. is described from Lake Rosario, Chubut Province, Argentina. It is characterized by a long neck forming an asymmetrical bulb with 2 well differentiated dorsal protruberances and 14 alternating rows of 13 and 14 proboscis hooks, each row with a stout fourth hook. It most closely resembles Pomphorhynchus sebastichthydis Yamaguti, 1939, from Japan, but differs in the bulb protruberances and in having more rows of hooks and more hooks per row and in the shapes of the fourth and basal hooks. Among American species P. patagonicus shows some similarities to Pomphorhynchus yamagutii Schmidt and Hugghins, 1973, from Chile, but differs with respect to the longer neck, bulb protruberances, and proboscis armature. Pomphorhynchus patagonicus is endemic to Patagonia, where its definitive type host is the endemic fish Patagonina hatcheri (Atherinidae) and its intermediate host the endemic freshwater amphipod Hyalella patagonica. It has been found also in autochthonous fishes belonging to the families Galaxiidae and Percichthyidae and in introduced salmonid fishes.     

Molecular evidence of cryptic diversity in Paracaryophyllaeus (Cestoda: Caryophyllidea), parasites of loaches (Cobitidae) in Eurasia,including description of P. vladkae n. sp.

Molecular phylogenetic analysis of an extensive collection of monozoic tapeworms of the genus Paracaryophyllaeus Kulakovskaya, 1961 (Cestoda: Caryophyllidea), parasites of loaches (Cypriniformes: Cobitidae) in Eurasia, has revealed cryptic species diversity within this long-time monotypic genus, especially in the Paracaryophyllaeus gotoi (Motomura, 1927) species complex [syn. Paracaryophyllaeus dubininorum (Kulakovskaya, 1961); type species]. Three independent, well-supported clades were discovered on the basis of molecular data: (i) specimens from Misgurnus anguillicaudatus and Cobitis lutheri from China, Russian Far East and Japan — called herein P. cf. gotoi 1, which may be conspecific with P. gotoi (Motomura, 1927), although in the absence of sequence data for P. gotoi from its type locality (basin of the River Kumkan in Korea), no certain inferences about their identity can currently be made; (ii) specimens from M. anguillicaudatus from China and Japan — P. cf. gotoi 2, which are morphologically indistinguishable from those of P. cf. gotoi 1; and (iii) morphologically distinct tapeworms from the endemic loach Cobitis bilseli from southwestern Turkey (Beyşehir Lake), which are described herein as a new species. Paracaryophyllaeus vladkae Scholz, Oros and Aydoğdu n. sp. differs from the remaining species of the genus in the following characteristics: the testes begin anterior to the first vitelline follicles (versus posterior), the body is short and robust (versus more elongate and slender), and the scolex is wide, rounded or apically tapered (versus claviform to truncate). Species composition of the genus, host specificity of species and geographical distribution are briefly discussed.     

Microsporidian Parasites Found in the Hemolymph of Four Baikalian Endemic Amphipods

At present, approximately 187 genera and over 1300 species of Microsporidia have been described, among which almost half infect aquatic species and approximately 50 genera potentially infect aquatic arthropods. Lake Baikal is the deepest and one of the oldest lakes in the world, and it has a rich endemic fauna with a predominance of arthropods. Among the arthropods living in this lake, amphipods (Crustacea) are the most dominant group and are represented by more than 350 endemic species. Baikalian amphipods inhabit almost all depths and all types of substrates. The age and geographical isolation of this group creates excellent opportunities for studying the diversity, evolution and genetics of host-parasite relationships. However, despite more than 150 years of study, data investigating the microsporidia of Lake Baikal remain incomplete. In this study, we used molecular genetic analyses to detect microsporidia in the hemolymph of several endemic species of amphipods from Lake Baikal. We provide the first evidence that microsporidian species belonging to three genera (Microsporidium, Dictyocoela and Nosema) are present in the hemolymph of Baikalian endemic amphipods. In the hemolymph of Eulimnogammarus verrucosus, we detected SSU rDNA of microsporidia belonging to the genus Nozema. In the hemolymph of Pallasea cancellous, we found the DNA of Microsporidium sp. similar to that in other Baikalian endemic amphipods; Dictyocoela sp. was found in the hemolymph of Eulimnogammarus marituji and Acanthogammarus lappaceus longispinus.