@article {1725, title = {Erratum to: Ammonia toxicity to the freshwater planarian Polycelis felina: contrasting effects of continuous versus discontinuous exposures}, journal = {Arch Environ Contam Toxicol}, volume = {69}, year = {2015}, month = {2015 Nov}, pages = {596}, issn = {1432-0703}, doi = {10.1007/s00244-015-0186-z}, author = {Alonso, Alvaro and Camargo, Julio A} } @article {1724, title = {Ammonia toxicity to the freshwater planarian Polycelis felina: contrasting effects of continuous versus discontinuous exposures}, journal = {Arch Environ Contam Toxicol}, volume = {68}, year = {2015}, month = {2015 May}, pages = {689-95}, abstract = {

Aquatic animals can be exposed to fluctuating concentrations of toxicants. In fact, for some toxicants (i.e., pesticides, ammonia), discontinuous exposure is more environmentally relevant than constant exposure. Responses of aquatic animals to each type of exposure may be different. However, despite the high ecological relevance of behaviour, there is still scarce information on the effects of discontinuous exposure on behaviour. Our study focused on the assessment of unionized ammonia toxicity on the behaviour of a freshwater planarian under continuous exposure (3 days of exposure and 18 days of recovery) versus discontinuous exposure (3 pulses of 1 day with 6 days of recovery between pulses = total 3 days of exposure and 18 days of recovery). Behaviour was assessed as locomotion activity. Bioassays with continuous and discontinuous exposure were performed with one control and five unionized ammonia concentrations (0.14-0.35 mg N-NH3/L). Unionized ammonia in continuous exposure caused less impact on behaviour than equivalent concentrations provided in a discontinuous exposure. By contrast, continuous exposures caused more impact on survival. The discontinuous exposure may allow detoxification during recovery periods, thus increasing the probability of survival in the next pulse. Under continuous exposure, the mortality threshold could be exceeded, and animals could die in greater proportion during exposure as well as the recovery period. We conclude that behavioural activity was a sensitive endpoint to assess the contrasting effects of continuous versus discontinuous exposure and that the response of planarians to discontinuous exposure is different to its response to continuous exposure.

}, keywords = {Ammonia, Animals, Biological Assay, Fresh Water, Lethal Dose 50, Locomotion, planarians, Toxicity Tests, Water Pollutants, Chemical}, issn = {1432-0703}, doi = {10.1007/s00244-015-0129-8}, author = {Alonso, Alvaro and Camargo, Julio A} } @article {1723, title = {Predator effects on a detritus-based food web are primarily mediated by non-trophic interactions}, journal = {J Anim Ecol}, volume = {83}, year = {2014}, month = {2014 Jul}, pages = {953-62}, abstract = {

Predator effects on ecosystems can extend far beyond their prey and are often not solely lethally transmitted. Change in prey traits in response to predation risk can have important repercussions on community assembly and key ecosystem processes (i.e. trait-mediated indirect effects). In addition, some predators themselves alter habitat structure or nutrient cycling through ecological engineering effects. Tracking these non-trophic pathways is thus an important, yet challenging task to gain a better grasp of the functional role of predators. Multiple lines of evidence suggest that, in detritus-based food webs, non-trophic interactions may prevail over purely trophic interactions in determining predator effects on plant litter decomposition. This hypothesis was tested in a headwater stream by modulating the density of a flatworm predator (Polycelis felina) in enclosures containing oak (Quercus robur) leaf litter exposed to natural colonization by small invertebrates and microbial decomposers. Causal path modelling was used to infer how predator effects propagated through the food web. Flatworms accelerated litter decomposition through positive effects on microbial decomposers. The biomass of prey and non-prey invertebrates was not negatively affected by flatworms, suggesting that net predator effect on litter decomposition was primarily determined by non-trophic interactions. Flatworms enhanced the deposition and retention of fine sediments on leaf surface, thereby improving leaf colonization by invertebrates - most of which having strong affinities with interstitial habitats. This predator-induced improvement of habitat availability was attributed to the sticky nature of the mucus that flatworms secrete in copious amount while foraging. Results of path analyses further indicated that this bottom-up ecological engineering effect was as powerful as the top-down effect on invertebrate prey. Our findings suggest that predators have the potential to affect substantially carbon flow and nutrient cycling in detritus-based ecosystems and that this impact cannot be fully appreciated without considering non-trophic effects.

}, keywords = {Animals, Biomass, Carbon Cycle, Food Chain, Geologic Sediments, Models, Biological, planarians, Plant Leaves, Predatory Behavior, Quercus, Rivers}, issn = {1365-2656}, doi = {10.1111/1365-2656.12189}, author = {Majdi, Nabil and Boich{\'e}, Anatole and Traunspurger, Walter and Lecerf, Antoine} } @article {1722, title = {Behavioral, morphological and histopathological effects of sublethal doses of quercetin on the species Polycelis felina (Dalyell)}, journal = {Folia Biol (Krakow)}, volume = {61}, year = {2013}, month = {2013}, pages = {101-6}, abstract = {

The effect of quercetin was studied on the multi-eyed flatworm Polycelis felina (Daly.) in laboratory conditions. This is a very suitable test-organism available year-round in nature, easily maintained in the laboratory. The results showed that depending on the dose and recovery period quercetin caused locomotory (behavioral) changes in treated animals including aggregation in groups, resting and unsynchronized movements and twisting of particular body parts. Morphological changes in the form of depigmentation of certain body parts were the result of damage or deterioration ofreticular and parenchymal cells. Numerous basophilic bodies representing parts of damaged and decomposed cells were determined in the gastroderm between the third and seventh day after treatment. All histological preparations revealed significant deterioration of cellular material, and therefore a damaging effect of quercetin on the multi-eyed flatworm Polycelis felina (Daly.). We found an increased number of neoblasts and reticular cells on the third day after treatment, so we concluded that quercetin in the applied doses had a stimulating effect on cell division of neoblasts and reticular cells of treated flatworms.

}, keywords = {Animals, Behavior, Animal, Motor Activity, Platyhelminths, Quercetin}, issn = {0015-5497}, author = {Rajevi{\'c}, Nives and Matkovi{\'c}, Helena and Gregorovi{\'c}, Gordana and Kovacevi{\'c}, Goran and Knezovi{\'c}, Lejla and Kalafati{\'c}, Mirjana} } @article {1721, title = {The freshwater planarian Polycelis felina as a sensitive species to assess the long-term toxicity of ammonia}, journal = {Chemosphere}, volume = {84}, year = {2011}, month = {2011 Jul}, pages = {533-7}, abstract = {

Behavioural endpoints are a good link between physiological and ecological effects. However long-term behavioural endpoints are not uniformly studied over all different organism groups. For example behaviour has been scarcely studied in planarians. Unionized ammonia (NH(3)) is one of the most widespread pollutants in developed countries, and is known to alter animal behaviour. In this study a long-term (30 d) bioassay was conducted to assess the effect of this pollutant on survival and behavioural activity (e.g. locomotion activity) of the freshwater planarian Polycelis felina. One control and three environmentally-realistic concentrations of unionized ammonia (treatments of 0.02, 0.05, and 0.09 mg N-NH(3) L(-1)) were used in quintuplicate. The behaviour of planarians was measured after 0, 10, 20 and 30 d of ammonia exposure. Mortality was recorded every 2 d. Unionized ammonia increased mortality in the two highest NH(3) concentrations and the locomotory activity was depressed in all treatments after 20 d of exposure. Behavioural effect was observed at concentrations 20 times lower than the short-term LC50 for this species. Previous studies proposed safe concentrations of unionized ammonia of 0.01-0.10 mg N-NH(3) L(-1) to aquatic ecosystems, but our study has shown that these concentrations will affect planarians. Because planarians play a key role in streams (as predator/scavenger), safe concentrations should be below 0.02 mg N-NH(3) L(-1) to protect this species in the freshwater community. Our results can contribute to improve the knowledge about ammonia toxicity to freshwater ecosystems, we recommend that safe concentrations of unionized ammonia should be based on very sensitive species.

}, keywords = {Ammonia, Animals, Environmental Monitoring, Fresh Water, planarians, Water Pollutants, Chemical}, issn = {1879-1298}, doi = {10.1016/j.chemosphere.2011.04.030}, author = {Alonso, Alvaro and Camargo, Julio A} } @article {1720, title = {Ameliorating effect of chloride on nitrite toxicity to freshwater invertebrates with different physiology: a comparative study between amphipods and planarians}, journal = {Arch Environ Contam Toxicol}, volume = {54}, year = {2008}, month = {2008 Feb}, pages = {259-65}, abstract = {

High nitrite concentrations in freshwater ecosystems may cause toxicity to aquatic animals. These living organisms can take nitrite up from water through their chloride cells, subsequently suffering oxidation of their respiratory pigments (hemoglobin, hemocyanin). Because NO(2)(-) and Cl(-) ions compete for the same active transport site, elevated chloride concentrations in the aquatic environment have the potential of reducing nitrite toxicity. Although this ameliorating effect is well documented in fish, it has been largely ignored in wild freshwater invertebrates. The aim of this study was to compare the ameliorating effect of chloride on nitrite toxicity to two species of freshwater invertebrates differing in physiology: Eulimnogammarus toletanus (amphipods) and Polycelis felina (planarians). The former species presents gills (with chloride cells) and respiratory pigments, whereas in the latter species these are absent. Test animals were exposed in triplicate for 168 h to a single nitrite concentration (5 ppm NO(2)-N for E. toletanus and 100 ppm NO(2)-N for P. felina) at four different environmental chloride concentrations (27.8, 58.3, 85.3, and 108.0 ppm Cl(-)). The number of dead animals and the number of affected individuals (i.e., number of dead plus inactive invertebrates) were monitored every day. LT(50) (lethal time) and ET(50) (effective time) were estimated for each species and each chloride concentration. LT(50) and ET(50) values increased with increases in the environmental chloride concentration, mainly in amphipods. Results clearly show that the ameliorating effect of chloride on nitrite toxicity was more significant in amphipods than in planarians, likely because of the absence of gills (with chloride cells) and respiratory pigments in P. felina. Additionally, this comparative study indicates that the ecological risk assessment of nitrite in freshwater ecosystems should take into account not only the most sensitive and key species in the communities, but also chloride levels in the aquatic environment.

}, keywords = {Amphipoda, Animals, Chlorides, Lethal Dose 50, Nitrites, planarians, Water Pollutants, Chemical}, issn = {0090-4341}, doi = {10.1007/s00244-007-9034-0}, author = {Alonso, A and Camargo, J A} } @article {1719, title = {Resistance of two planarian species to UV-irradiation}, journal = {Folia Biol (Krakow)}, volume = {54}, year = {2006}, month = {2006}, pages = {103-8}, abstract = {

The aim of this work was to determine the effects of 20, 25 and 30 minute UV-irradiation periods lambda = 253.5 nm to two planarian species Dugesia tigrina (Gir.) and Polycelis felina (Daly.). In vivo, UV light effects have been reported to affect intracellular receptors and disrupt simple behaviour. The effects of UV-rays on mortality and behavior as well as morphological, cytological and histological changes in the two planarian species were assessed, and the course and the dynamics of regenerative processes were compared between them. Experimental populations of Dugesia tigrina and Polycelis felina species were maintained in laboratory conditions at room temperature. Mortality, behavioral and morphological changes were monitored daily by means of a light stereomicroscope. For cytological and histopathological analysis, planarians were fixed in Bouine fixative on the first, second, third, fifth and seventh day after exposure to UV-irradiation, respectively. They were embedded in paraffin, cut on a microtome, stained with toluidin blue and embedded in Canada-balsam. UV-rays caused mortality, behavioral, morphological, cytological and histological changes in each planarian species. In regeneration of damaged body parts reticular cells and neoblasts played the main role. Neoblasts as totipotent cells extremely increased in number in the area of damaged tissue, immediately after UV-exposure. Dugesia tigrina was more sensitive to UV-rays than Polycelis felina due to possession of less pigmented cells. The course of regeneration in both species was similar. Most individuals of both species regenerated in 5 to 12 days after UV-irradiation.

}, keywords = {Animals, planarians, Ultraviolet Rays}, issn = {0015-5497}, author = {Kalafati{\'c}, Mirjana and Kovacevi{\'c}, Goran and Franjevi{\'c}, Damjan} } @article {1718, title = {Toxicity of nitrite to three species of freshwater invertebrates.}, journal = {Environ Toxicol}, volume = {21}, year = {2006}, month = {2006 Feb}, pages = {90-4}, abstract = {

Nitrite is a compound with a high toxicity to aquatic animals. Several anthropogenic pollution sources are increasing the concentrations of this component of the nitrogen cycle. Despite this toxicity, there is little available literature on its effects on freshwater invertebrates. Laboratory bioassays were performed to obtain data on the lethal effects of nitrite to three species of freshwater invertebrates: the planarian Polycelis felina and the amphipods Echinogammarus echinosetosus and Eulimnogammarus toletanus. The LC(50), LC(10), and LC(0.01) values (mg/L NO(2)--N) at 24, 48, 72, and 96 h were calculated for each species. E. toletanus and E. echinosetosus were the most sensitive species, with 96 h LC(50) values of 2.09 and 2.59 mg/L NO(2)--N, respectively. In contrast, the planarian P. felina showed a higher tolerance to nitrite, with a 96 h LC(50) value of 60.0 mg/L NO(2)--N. The obtained results were compared with the reported nitrite data for other freshwater invertebrates. This study may contribute to a more appropriate assessment of the ecological risk of this compound in freshwater ecosystems.

}, keywords = {Amphipoda, Animals, Lethal Dose 50, Nitrites, planarians, Rivers, Spain, Water Pollutants, Chemical}, issn = {1520-4081}, doi = {10.1002/tox.20155}, author = {Alonso, Alvaro and Camargo, Julio A} } @article {1717, title = {Toxicity testing of herbicide norflurazon on an aquatic bioindicator species--the planarian Polycelis felina (Daly.)}, journal = {Aquat Toxicol}, volume = {73}, year = {2005}, month = {2005 Jul 30}, pages = {342-52}, abstract = {

Norflurazon is a bleaching, preemergence herbicide. Due to its mobility and long half-life it presents a potential for groundwater contamination. The aim of our study was to investigate toxic effects of norflurazon on non-targeted aquatic bioindicator organism, the planarian Polycelis felina (Daly.). Animals were exposed to water solutions of norflurazon in concentrations 200, 20, 2 and 0.2 microM. Mortality, locomotive and morphological changes were monitored. Histological changes were studied both on treated and control animals with light microscopy. The primary DNA damage on single planarian cells was studied using the alkaline comet assay. Three comet parameters were studied: tail length, percentage of DNA in comet tail and tail moment. The results showed that norflurazon caused mortality, locomotive, morphological and histological changes in treated animals compared to corresponding controls. The most prominent histological changes were damage of the outer mucous layer, lack of rhabdites, damage to epidermis and extensive damage to parenchyma cells. The results of alkaline comet assay indicated that norflurazon in concentrations of 2 and 0.2 microM induces significant increase of primary DNA damage in planarian cells compared to the corresponding control animals. The mean values of all three measured parameters were significantly elevated on the fourth day of the treatment compared with the first and the seventh day. Based on the results of mortality and locomotive observations, we conclude that the fourth day of the treatment represents a certain threshold within planarian metabolism followed by the beginning of detoxification and recovery. However, histological preparations and comet data statistics show results indicating that high toxicity on the seventh day of the treatment gave the results of decrease of DNA damage due to the tissue/cell damage (apoptosis) and not recovery. The present study showed the ability of norflurazon to induce a wide range of different toxicological responses in freshwater planarian Polycelis felina (Daly.).

}, keywords = {Animals, Comet Assay, Croatia, DNA Damage, Dose-Response Relationship, Drug, Herbicides, Histological Techniques, Locomotion, Mortality, planarians, Pyridazines, Time Factors}, issn = {0166-445X}, doi = {10.1016/j.aquatox.2005.03.023}, author = {Horvat, T and Kalafati{\'c}, M and Kopjar, N and Kovacevi{\'c}, G} } @article {1716, title = {Karyological analysis of two allopatric populations of planarian Polycelis felina (Daly.) in Croatia}, journal = {Folia Biol (Krakow)}, volume = {52}, year = {2004}, month = {2004}, pages = {131-3}, abstract = {

The results of preliminary karyological investigations of two geographically distant and morphologically slightly different Polycelis felina (Daly.) populations from central Croatia are reported. The results have shown that individuals of both populations are diploids, with the same chromosome number in their neoblasts (2n=18). Their karyotypes were composed of nine chromosome pairs, three of them are metacentric and the other six are submetacentric. Statistical evaluation of data indicated that both populations of Polycelis felina (Daly.), despite minor differences observed between them, belong to the same karyological biotype.

}, keywords = {Animals, Chromosomes, Croatia, Geography, Karyotyping, planarians, Species Specificity}, issn = {0015-5497}, author = {Kalafati{\'c}, Mirjana and Kopjar, Nevenka and Zrna, Gordana and Zupan, Irina and Kovacevi{\'c}, Goran and Franjevi{\'c}, Damjan} } @article {1715, title = {The impairments of neoblast division in regenerating planarian Polycelis felina (Daly.) caused by in vitro treatment with cadmium sulfate}, journal = {Toxicol In Vitro}, volume = {18}, year = {2004}, month = {2004 Feb}, pages = {99-107}, abstract = {

The effects of cadmium sulfate on the neoblast mitotic activity in regenerating planarian Polycelis felina (Daly.) were investigated. Mitotic abnormalities and chromosomal aberrations were evaluated after 6-h treatment and 24-h recovery period. The blastema were fixed, and examined cytologically through routine lactoorceine squash preparations. Mitotic indices were also determined. Cadmium sulfate induced a dose-dependent decrease in neoblast mitotic activity, accompanied with disturbances in distribution of cells over mitotic phases. Different cytological abnormalities with varying frequency were observed. Marked mitotic depression was concentration-dependent. Toxic effects of cadmium in regenerating planarian were mainly associated with mitotic spindle disturbances. Immediately after treatment mitotic abnormalities were prevalent over chromosomal and C-mitosis was the most prominent one. After 24-h recovery period a prevalence of mitotic over chromosomal aberrations was still present in animals treated with two higher concentrations of cadmium sulfate. However, the proportions of cells with chromosome stickiness in all treated animals were significantly increased compared to their post-treatment values. Observed mitotic impairments could be related to mitotic arrest contributing to retardations and delays, especially in animals treated with the highest concentration tested. The results obtained indicated usefulness of short term invertebrate assays as an alternative to in vitro pre-screening of toxic chemicals.

}, keywords = {Animals, Biological Assay, Cadmium Compounds, Cell Division, Chromosome Aberrations, Croatia, Dose-Response Relationship, Drug, Drug Evaluation, Preclinical, Female, Forecasting, Mitosis, Mitotic Index, Mortality, Oxygen Consumption, planarians, regeneration, Sulfates, Survival, Time Factors}, issn = {0887-2333}, author = {Kalafati{\'c}, M and Kopjar, N and Besendorfer, V} } @article {1714, title = {The responses to current flow of two stream dwelling triclads, Crenobia alpina (Dana) and Polycelis felina (Dalyell)}, journal = {Oecologia}, volume = {10}, year = {1972}, month = {1972 Dec}, pages = {313-320}, abstract = {

An apparatus is described which allows triclads to choose between the fast and slow regions of a stirred tank. In the absence of a stone substratum Crenobia alpina preferred or tolerated higher current speeds than Polycelis felina, this effect was enhanced when a stone substratum was added to the apparatus. These results indicate that the absence of Polycelis felina from the steep gradient regions of streams could be accounted for by its preference for slower micro-currents. Conversely the presence of Crenobia alpina in steep gradient regions could be accounted for by its preference for or tolerance to higher micro-currents.

}, issn = {1432-1939}, doi = {10.1007/BF00345735}, author = {Lock, Maurice A} } @article {1713, title = {The effects of electrofishing on the invertebrates of a Lake District stream}, journal = {Oecologia}, volume = {9}, year = {1972}, month = {1972 Mar}, pages = {1-11}, abstract = {

The experiments were performed in Dale Park Beck, a stony stream in the English Lake District. Two operators electrofished the sampling area (length 20 m in April and July 1970, and 40 m in May 1971) three times (runs 1, 2, 3) in each experiment.Electrofishing caused a marked increase in the number of invertebrates drifting out of the sampling area, and nearly all taxa taken in the bottom samples were also found in the drift samples. The fish shocker was chiefly responsible for the increased drifting of Plecoptera, Ephemeroptera and Gammarus pulex, and these taxa were dislodged from the substratum more easily than Trichoptera, Coleoptera, Diptera and Polycelis felina. The increased drifting of the latter taxa was chiefly due to the disturbance of the substratum by the two operators.Most of the invertebrates drifting from the upstream end of the experimental section returned to the bottom within the sampling area. The invertebrate drift out of the sampling area came chiefly from the downstream end of the section, and was equivalent to a loss of only 5\% from the total benthos in the sampling area (losses varied between \<1 and 13\% for individual taxa).

}, issn = {1432-1939}, doi = {10.1007/BF00345239}, author = {Elliott, J M and Bagenal, T B} } @article {1712, title = {The distances travelled by drifting invertebrates in a Lake District stream}, journal = {Oecologia}, volume = {6}, year = {1971}, month = {1971 Dec}, pages = {350-379}, abstract = {

The distances travelled by drifting invertebrates of 18 taxa were investigated at sites 3 and 4 in the Wilfin Beck, a small stony stream in the English Lake District. Fifty invertebrates of the same taxon were released into the stream at increasing distances upstream from a large net which caught all invertebrates drifting downstream.The relationship between the catch in the net (Y x ) and the distance from the release point to the net (X m) was well described by the regression equation:[Formula: see text] whereR is the constant relative rate of return of invertebrates to the bottom of the stream, andA=Y 0=number of invertebrates released at each point=50. Values ofR, the mean drift distance ([Formula: see text] m), and the distance (X p m) travelled byP\% (1\%, 10\%, 50\%) of the drifting invertebrates were calculated for each taxon at different modal water velocities. Values ofR,[Formula: see text] andX p were fairly constant for each taxon at a particular modal water velocity, and were not significantly affected by the source of the experimental animals (benthos or drift), by changes in illumination (daylight or darkness), or by seasonal changes, including water temperature.The experimental taxa at site 4 were divided into the following three groups according to their ability to return to the bottom: 1. Polycelis felina, Ancylus fluviatilis, Chironomidae, Eliminthidae, andAmphinemura sulcicollis. Values ofR,[Formula: see text],X p not significantly different from those obtained for dead invertebrates, which were removed from the drift by chance effects. 2. Protonemura meyeri, Leuctra spp.,Chloroperla spp.,Rhithrogena semicolorata, Simulium spp. Values ofR,[Formula: see text],X p not significantly different from those obtained for dead invertebrates at modal water velocities ≧19 cm/sec. At low velocities (10-12 cm/sec),R was significantly greater and[Formula: see text],X p significantly smaller than values obtained for dead invertebrates. 3. Erpobdella octoculata, Gammarus pulex, Hydropsyche spp.,Ecdyonurus venosus, Ephemerella ignita, Ba\ëtis rhodani. Values ofR,[Formula: see text],X p significantly different (R greater,[Formula: see text] andX p smaller) from those obtained for dead invertebrates. The exponential law was not a good model for experiments with cased caddis larvae (Agapetus fuscipes and a mixed group ofSericostoma personatum, Drusus annulatus, Potamophylax cingulatus). Larvae sank rapidly after release and drifted over very short distances.Values ofR for each taxon were significantly higher at site 3 than at site 4, and the more rapid return at site 3 was presumably due to dense stands of aquatic macrophytes. The increase inR was greatest forSimulium spp. andE. ignita.The relationship between[Formula: see text] and modal water velocity (V cm/sec) was well described by the regression equation:[Formula: see text] wherea andb are constants. The relationship betweenR andV, orX p andV, was described by similar equations. Values ofa andb were calculated for each taxon at sites 3 and 4.The drift distance was also investigated by blocking the total drift and taking drift samples at several stations downstream from the blockage. Drift rate was markedly reduced immediately below the blockage and then gradually increased downstream until it was similar to that recorded before blocking. The mathematical model developed from the detailed experiments was a good fit to the results of the blocking experiments.The behaviour of the drifting invertebrates and their ability to return to the bottom are discussed. From the results of the present study and those of other workers, it is concluded that the mathematical model is a good model for invertebrate drift. The implications of the model are discussed, especially the relationship between drift rate and water velocity, and the proportion of the benthos in the drift.

}, issn = {1432-1939}, doi = {10.1007/BF00389109}, author = {Elliott, J M} } @article {ECE3:ECE31969, title = {Chromosome numbers in three species groups of freshwater flatworms increase with increasing latitude}, journal = {Ecology and Evolution}, year = {2016}, pages = {n/a{\textendash}n/a}, abstract = {Polyploidy in combination with parthenogenesis offers advantages for plasticity and the evolution of a broad ecological tolerance of species. Therefore, a positive correlation between the level of ploidy and increasing latitude as a surrogate for environmental harshness has been suggested. Such a positive correlation is well documented for plants, but examples for animals are still rare. Species of flatworms (Platyhelminthes) are widely distributed, show a remarkably wide range of chromosome numbers, and offer therefore good model systems to study the geographical distribution of chromosome numbers. We analyzed published data on counts of chromosome numbers and geographical information of three flatworm {\textquotedblleft}species{\textquotedblright} (Phagocata vitta, Polycelis felina and Crenobia alpina) sampled across Europe (220 populations). We used the mean chromosome number across individuals of a population as a proxy for the level of ploidy within populations, and we tested for relationships of this variable with latitude, mode of reproduction (sexual, asexual or both) and environmental variables (annual mean temperature, mean diurnal temperature range, mean precipitation and net primary production). The mean chromosome numbers of all three species increased with latitude and decreased with mean annual temperature. For two species, chromosome number also decreased with mean precipitation and net primary production. Furthermore, high chromosome numbers within species were accompanied with a loss of sexual reproduction. The variation of chromosome numbers within individuals of two of the three species increased with latitude. Our results support the hypothesis that polyploid lineages are able to cope with harsh climatic conditions at high latitudes. Furthermore, we propose that asexual reproduction in populations with high levels of polyploidization stabilizes hybridization events. Chromosomal irregularities within individuals tend to become more frequent at the extreme environments of high latitudes, presumably because of mitotic errors and downsizing of the genome.}, keywords = {Geographical range, parthenogenesis, Platyhelminthes, polyploidy, reproduction}, issn = {2045-7758}, doi = {10.1002/ece3.1969}, url = {http://dx.doi.org/10.1002/ece3.1969}, author = {Lorch, Sven and Zeuss, Dirk and Brandl, Roland and Br{\"a}ndle, Martin} } @article {307, title = {Freshwater planarians (Platyhelminthes, Tricladida) from the Palearctic section of the African continent: new records, with the description of a new species}, journal = {Zootaxa}, volume = {3182}, year = {2012}, pages = {1-15}, author = {Harrath, A. H. and Ronald Sluys and Merzoug, D. and Yacoubi-Khebiza, M. and Saleh Alwasel and Marta Riutort} } @article {308, title = {A new species of Dugesia (Platyhelminthes, Tricladida, Dugesiidae) from the Afromontane forest in South Africa, with an overview of freshwater planarians from the African continent}, journal = {Zootaxa}, volume = {3551}, year = {2012}, pages = {43{\textendash}58}, author = {Giacinta Angela Stocchino and Ronald Sluys and Manconi, Renata} }