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Ronald Sluys - One of the best experts on this subject based on the ideXlab platform.
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molecular and morphological identification of two new african species of Dugesia platyhelminthes tricladida dugesiidae from cameroon
Journal of Natural History, 2019Co-Authors: Abdel Halim Harrath, Ronald Sluys, Waleed Aldahmash, Saleh H Alwasel, Lamjed Mansour, Guy Benoit Lekeufack Folefack, Eduard Sola, Marta RiutortAbstract:ABSTRACTThe paper describes two new Dugesia species collected from the rivers Messassi and Ntsetsensooh in Cameroon, representing the first planarian flatworms documented from this country. Based on morphological data, the new species Dugesia bijuga Harrath & Sluys, sp. nov. is characterized mainly by the presence of two diaphragms, a barrel-shaped penis that is traversed by numerous ducts of penis glands and is provided with a short nozzle, and the presence of two atrial folds. The other new species, Dugesia pustulata Harrath & Sluys, sp. nov., is characterized mainly by absence of a penis bulb, presence of a large, elongated and weakly muscular seminal vesicle, and by the ventroposterior section of the bursal canal being thrown into distinct folds. The phylogenetic position of the two new species was determined through a molecular phylogenetic tree, based on a mitochondrial and a nuclear gene, including species from the major geographical range of distribution of the genus Dugesia. The phylogenetic tree...
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a new and aberrant species of Dugesia platyhelminthes tricladida dugesiidae from madagascar
ZooKeys, 2014Co-Authors: Giacinta Angela Stocchino, Ronald Sluys, Renata ManconiAbstract:In this paper we report a new species of Dugesia of the family Dugesiidae from Madagascar, representing the fourth species of freshwater planarian known from this global biodiversity hotspot. In some respects the new species is aberrant, when compared with its congeners, being characterized by a head with smoothly rounded auricles, a peculiar course of the oviducts, including the presence of a common posterior extension, and by the asymmetrical openings of the vasa deferentia at about halfway along the seminal vesicle. Further, it is characterized by a ventral course of the ejaculatory duct with a terminal opening, very long spermiducal vesicles and unstalked cocoons. Its diploid chromosome complement with 18 chromosomes represents an uncommon feature among fissiparous species of Dugesia .
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reproductive strategies karyology parasites and taxonomic status of Dugesia populations from yemen platyhelminthes tricladida dugesiidae
Zoological Science, 2013Co-Authors: Abdul Halim Harrath, Ronald Sluys, Waleed Aldahmash, Abdulkarim Alrazaki, Saleh H AlwaselAbstract:We present new data on the distribution, reproductive strategies, karyology, and taxonomic status of populations of freshwater planarians from Yemen. Nine populations were sampled and significant differences in their reproductive strategies and karyology are reported. The present study presents the first fully documented record of a naturally sexual, diploid (2n = 18) population of a Dugesia species in the eastern part of the Afrotropical region. Morphological characters combined with karyological data suggest that these Dugesia populations from Yemen represent a new species, which is herein described as Dugesia arabica Harrath and Sluys, sp. nov. This new species is mainly distinguishable from other Dugesia species that are distributed exclusively in the Mediterranean basin and in the eastern part of the Afrotropical region by the presence of the following features: well-developed and cone-shaped penis papilla, housing an ejaculatory duct that runs ventrally and has a subterminal and ventral opening; a c...
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fluvial basin history in the northeastern mediterranean region underlies dispersal and speciation patterns in the genus Dugesia platyhelminthes tricladida dugesiidae
Molecular Phylogenetics and Evolution, 2013Co-Authors: Eduard Sola, Ronald Sluys, Konstantinos Gritzalis, Marta RiutortAbstract:Abstract In this study we analyzed the phylogenetic relationships of eastern Mediterranean freshwater planarians of the genus Dugesia, estimated divergence times for the various clades, and correlated their phylogeographic patterns with geological and paleoclimatic events, in order to discover which evolutionary processes have shaped the present-day distribution of these animals. Specimens were collected from freshwater courses and lakes in continental and insular Greece. Genetic divergences and phylogenetic relationships were inferred by using the mitochondrial gene subunit I of cytochrome oxidase (COI) and the nuclear ribosomal internal transcribed spacer-1 (ITS-1) from 74 newly collected individuals from Greece. Divergence time estimates were obtained under a Bayesian framework, using the COI sequences. Two alternative geological dates for the isolation of Crete from the mainland were tested as calibration points. A clear phylogeographic pattern was present for Dugesia lineages in the Eastern Mediterranean. Morphological data, combined with information on genetic divergences, revealed that eight out of the nine known species were represented in the samples, while additional new, and still undescribed species were detected. Divergence time analyses suggested that Dugesia species became isolated in Crete after the first geological isolation of the island, and that their present distribution in the Eastern Mediterranean has been shaped mainly by vicariant events but also by dispersal. During the Messinian salinity crisis these freshwater planarians apparently were not able to cross the sea barrier between Crete and the mainland, while they probably did disperse between islands in the Aegean Sea. Their dependence on freshwater to survive suggests the presence of contiguous freshwater bodies in those regions. Our results also suggest a major extinction of freshwater planarians on the Peloponnese at the end of the Pliocene, while about 2 Mya ago, when the current Mediterranean climate was established, these Peloponnese populations probably began to disperse again. At the end of the Pliocene or during the Pleistocene, mainland populations of Dugesia colonized the western coast, including the Ionian Islands, which were then part of the continent.
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african planarians morphology and karyology of Dugesia maghrebiana sp n platyhelminthes tricladida from tunisia
Italian Journal of Zoology, 2009Co-Authors: Giacinta Angela Stocchino, Ronald Sluys, G Corso, Renata Manconi, Salvatore Casu, Maria PalaAbstract:Extensive surveys were made of Tunisian freshwaters, yielding freshwater planarians at only one locality in southeastern Tunisia, representing a new species. Dugesia maghrebiana sp. n. is characterized by the presence of the following features: ventral course of the ejaculatory duct, terminal opening of the ejaculatory duct, double diaphragm, symmetrical openings of the oviducts into the bursal canal, and by a typical condition of mixoploidy with a double aneuploidic chromosome complement. The taxonomic position of the new species is discussed in relation to other African and Mediterranean species.
Giacinta Angela Stocchino - One of the best experts on this subject based on the ideXlab platform.
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African planarians: Dugesia aethiopica sp. n. (Platyhelminthes, Tricladida) from lake Tana (NW Ethiopia)
Italian Journal of Zoology, 2020Co-Authors: Giacinta Angela Stocchino, G Corso, Renata Manconi, Maria PalaAbstract:A new species of Dugesia from East Africa is described as a first report of Platyhelminthes from Lake Tana. Dugesia aethiopica sp. n. is characterized by the shape of its bursa copulatrix; length, diameter, course, and opening of the bursal canal; opening of the oviducts; shape of the penis papilla; penial parenchymatic cavity. The taxonomic position of the new species within the D. gonocephala group is discussed in comparison with the other African and Madagascan species.
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Dugesia hepta and Dugesia benazzii (Platyhelminthes: Tricladida): two sympatric species with occasional sex?
Organisms Diversity & Evolution, 2020Co-Authors: Daniel Dols-serrate, Laia Leria, Juan Pablo Aguilar, Giacinta Angela Stocchino, Marta RiutortAbstract:Dugesia hepta Pala, Casu & Vacca, 1981 and Dugesia benazzii Lepori, 1951 are two freshwater planarian species from the islands of Corsica and Sardinia. Dugesia hepta is endemic of Sardinia and distributed in four northern hydrographic basins where it co-occurs with D. benazzii , which has a wider Tyrrhenian distribution. Although these species have been broadly studied—especially D. benazzii —as regards to their variety of reproductive patterns as well as for their karyological diversity, little is known about them from a molecular phylogenetic perspective. For the first time, we present a molecular phylogenetic tree of the two species and their populations based on two molecular markers—one mitochondrial, Cox1 , and one nuclear, Dunuc12 . Our results not only confirm that both species are molecularly distinct but also show that D. benazzii ’s Corsican and Sardinian populations could belong to separate species. Furthermore, we present the first demonstration of a natural hybridization between different species in the genus Dugesia on the basis of molecular data .
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a new and aberrant species of Dugesia platyhelminthes tricladida dugesiidae from madagascar
ZooKeys, 2014Co-Authors: Giacinta Angela Stocchino, Ronald Sluys, Renata ManconiAbstract:In this paper we report a new species of Dugesia of the family Dugesiidae from Madagascar, representing the fourth species of freshwater planarian known from this global biodiversity hotspot. In some respects the new species is aberrant, when compared with its congeners, being characterized by a head with smoothly rounded auricles, a peculiar course of the oviducts, including the presence of a common posterior extension, and by the asymmetrical openings of the vasa deferentia at about halfway along the seminal vesicle. Further, it is characterized by a ventral course of the ejaculatory duct with a terminal opening, very long spermiducal vesicles and unstalked cocoons. Its diploid chromosome complement with 18 chromosomes represents an uncommon feature among fissiparous species of Dugesia .
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african planarians morphology and karyology of Dugesia maghrebiana sp n platyhelminthes tricladida from tunisia
Italian Journal of Zoology, 2009Co-Authors: Giacinta Angela Stocchino, Ronald Sluys, G Corso, Renata Manconi, Salvatore Casu, Maria PalaAbstract:Extensive surveys were made of Tunisian freshwaters, yielding freshwater planarians at only one locality in southeastern Tunisia, representing a new species. Dugesia maghrebiana sp. n. is characterized by the presence of the following features: ventral course of the ejaculatory duct, terminal opening of the ejaculatory duct, double diaphragm, symmetrical openings of the oviducts into the bursal canal, and by a typical condition of mixoploidy with a double aneuploidic chromosome complement. The taxonomic position of the new species is discussed in relation to other African and Mediterranean species.
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Endemic freshwater planarians of Sardinia: Redescription of Dugesia hepta (Platyhelminthes, Tricladida) with a comparison of the Mediterranean species of the genus
Journal of Natural History, 2005Co-Authors: Giacinta Angela Stocchino, G Corso, Renata Manconi, Salvatore Casu, Maria PalaAbstract:The endemic freshwater planarian Dugesia hepta from Sardinia was described mainly by karyology and karyotype analysis and by geographic distribution. The present paper reports on the detailed morphological study of the copulatory apparatus and highlights the fact that the exclusive diagnostic characters of D. hepta are the shape of the penis papilla, the course and opening of the ejaculatory duct and the openings of the shell glands. A neotype is designated on the basis of a detailed description, and the geographic range of the species is better defined. The two phylogenetically important traits represented by the course and opening of the ejaculatory duct show an unknown condition in the genus Dugesia, diverging from the typical one displayed by the other 69 species. A comparative analysis of morphological traits of the 20 Mediterranean species of the genus Dugesia was made.
J. O. Young - One of the best experts on this subject based on the ideXlab platform.
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continuing dispersal of freshwater triclads platyhelminthes turbellaria in britain with particular reference to lakes
Freshwater Biology, 1999Co-Authors: J. O. Young, T. B. ReynoldsonAbstract:1. A survey of lakes in Anglesey and Snowdonia, Wales, in the summer of 1997 recorded changes in the triclad fauna which had occurred since earlier studies in the 1950s and in 1973. Two native species, Polycelis tenuis and Dugesia polychroa, and two immigrants, Planaria torva and especially Dugesia tigrina, have increased their range. The triclad fauna has remained unchanged with time in eleven out of sixteen lakes in Snowdonia, in contrast to only one out of fourteen lakes on Anglesey. This supports the hypothesis produced in the 1950s, that the triclad fauna of the ion-poor, unproductive lakes in Snowdonia would change little with time, being maintained by ecological interactions, whereas the ion-rich, productive lakes on Anglesey, from which native Dugesia spp. and Dendrocoelum lacteum are historically absent, would increase in triclad diversity. 2. An examination of national records for the distribution of D. tigrina and Pl. torva indicated their continuing dispersal in both still and running waters in mainland Britain, with the former species having the greater frequency of occurrence. 3. The reasons for this may be that D. tigrina is (a) more easily dispersed, (b) a more opportunistic, catholic feeder, (c) a more vigorous competitor, (d) able to reproduce asexually and (e) able to prey to some extent on other triclad species, as shown in the laboratory but not yet confirmed in the field. The absence of D. tigrina and Pl. torva from unproductive lakes may be explained in terms of low temperature and feeding mode, and a low standing crop of gastropods, respectively. 4. Seven surveys (1961–1997) of the triclad fauna (six species) of Colemere, England, revealed that D. tigrina was confined to one small area of the littoral zone until the mid-1980s, after which it spread fairly rapidly to occupy the entire shore by 1997. Its expansion has been to the detriment of all the native species, particularly P. tenuis, except Dd. lacteum. The possible extinction of Pl. torva may be linked to a numerical reduction in snails, particularly Potamopyrgus jenkinsi. 5. Dugesia tigrina has an adverse effect on the native triclad fauna in lakes, particularly when only a few species are present. This has been explained in terms of the availability of a wider variety of food. The presence of a larger number of triclad species denies the immigrant food items, particularly crustaceans and snails, the food refuges of Dd. lacteum and Dugesia spp., respectively. However, the long-term study of Colemere has shown that more diverse triclad faunas may also be vulnerable to this immigrant. The effect of Pl. torva on native triclads remains uncertain.
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The consequence of a food refuge collapse on a guild of lake-dwelling triclads and leeches
Hydrobiologia, 1994Co-Authors: A. J. Martin, R. M. H. Seaby, J. O. YoungAbstract:The diets of Polycelis nigra, P. tenuis, Dugesia polychroa, Dendrocoelum lacteum, Glossiphonia complanata, Helobdella stagnalis and Erpobdella octoculata in an English lake were examined, using a serological technique, and compared between 1981–82 and 1989–90. Leech, triclad and prey abundances were also recorded. Between the two studies, snail numbers crashed whereas the abundances of Asellus and Gammarus increased. Dugesia and Glossiphonia numbers decreased substantially, whilst Polycelis tenuis and Helobdella abundances increased. In the second study, the snail component in the diet was greatly reduced resulting in a broader food niche, particularly for Dugesia and Glossiphonia , and greater food overlap between the predators with the exception of Dendrocoelum and Erpobdella which do not eat molluscs. It is postulated that the reduced size of the snail refuge, and consequent increase in severity of interspecific competition with other predators, particularly Polycelis and Helobdella , led to the observed decrease in abundances of Dugesia and Glossiphonia . The decline in the last two genera, perhaps coupled with increased crustacean abundance, could have contributed to the numerical increase of the competitively superior Polycelis tenuis and Helobdella .
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the food niches of the invasive Dugesia tigrina girard and indigenous polycelis tennis ijima and p nigra muller turbellaria tricladida in a welsh lake
Hydrobiologia, 1993Co-Authors: J. O. YoungAbstract:The invasion of Llyn Coron in North Wales by the American immigrant Dugesia tigrina resulted in the almost entire displacement of the native Polycelis tenuis and P. nigra populations. Because competition for food is the most important factor controlling and regulating populations of British lake-dwelling triclads, the diets of the invasive and native triclads in the lake were examined in an attempt to explain the successful invasion.
Marta Riutort - One of the best experts on this subject based on the ideXlab platform.
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Dugesia hepta and Dugesia benazzii (Platyhelminthes: Tricladida): two sympatric species with occasional sex?
Organisms Diversity & Evolution, 2020Co-Authors: Daniel Dols-serrate, Laia Leria, Juan Pablo Aguilar, Giacinta Angela Stocchino, Marta RiutortAbstract:Dugesia hepta Pala, Casu & Vacca, 1981 and Dugesia benazzii Lepori, 1951 are two freshwater planarian species from the islands of Corsica and Sardinia. Dugesia hepta is endemic of Sardinia and distributed in four northern hydrographic basins where it co-occurs with D. benazzii , which has a wider Tyrrhenian distribution. Although these species have been broadly studied—especially D. benazzii —as regards to their variety of reproductive patterns as well as for their karyological diversity, little is known about them from a molecular phylogenetic perspective. For the first time, we present a molecular phylogenetic tree of the two species and their populations based on two molecular markers—one mitochondrial, Cox1 , and one nuclear, Dunuc12 . Our results not only confirm that both species are molecularly distinct but also show that D. benazzii ’s Corsican and Sardinian populations could belong to separate species. Furthermore, we present the first demonstration of a natural hybridization between different species in the genus Dugesia on the basis of molecular data .
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molecular and morphological identification of two new african species of Dugesia platyhelminthes tricladida dugesiidae from cameroon
Journal of Natural History, 2019Co-Authors: Abdel Halim Harrath, Ronald Sluys, Waleed Aldahmash, Saleh H Alwasel, Lamjed Mansour, Guy Benoit Lekeufack Folefack, Eduard Sola, Marta RiutortAbstract:ABSTRACTThe paper describes two new Dugesia species collected from the rivers Messassi and Ntsetsensooh in Cameroon, representing the first planarian flatworms documented from this country. Based on morphological data, the new species Dugesia bijuga Harrath & Sluys, sp. nov. is characterized mainly by the presence of two diaphragms, a barrel-shaped penis that is traversed by numerous ducts of penis glands and is provided with a short nozzle, and the presence of two atrial folds. The other new species, Dugesia pustulata Harrath & Sluys, sp. nov., is characterized mainly by absence of a penis bulb, presence of a large, elongated and weakly muscular seminal vesicle, and by the ventroposterior section of the bursal canal being thrown into distinct folds. The phylogenetic position of the two new species was determined through a molecular phylogenetic tree, based on a mitochondrial and a nuclear gene, including species from the major geographical range of distribution of the genus Dugesia. The phylogenetic tree...
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fluvial basin history in the northeastern mediterranean region underlies dispersal and speciation patterns in the genus Dugesia platyhelminthes tricladida dugesiidae
Molecular Phylogenetics and Evolution, 2013Co-Authors: Eduard Sola, Ronald Sluys, Konstantinos Gritzalis, Marta RiutortAbstract:Abstract In this study we analyzed the phylogenetic relationships of eastern Mediterranean freshwater planarians of the genus Dugesia, estimated divergence times for the various clades, and correlated their phylogeographic patterns with geological and paleoclimatic events, in order to discover which evolutionary processes have shaped the present-day distribution of these animals. Specimens were collected from freshwater courses and lakes in continental and insular Greece. Genetic divergences and phylogenetic relationships were inferred by using the mitochondrial gene subunit I of cytochrome oxidase (COI) and the nuclear ribosomal internal transcribed spacer-1 (ITS-1) from 74 newly collected individuals from Greece. Divergence time estimates were obtained under a Bayesian framework, using the COI sequences. Two alternative geological dates for the isolation of Crete from the mainland were tested as calibration points. A clear phylogeographic pattern was present for Dugesia lineages in the Eastern Mediterranean. Morphological data, combined with information on genetic divergences, revealed that eight out of the nine known species were represented in the samples, while additional new, and still undescribed species were detected. Divergence time analyses suggested that Dugesia species became isolated in Crete after the first geological isolation of the island, and that their present distribution in the Eastern Mediterranean has been shaped mainly by vicariant events but also by dispersal. During the Messinian salinity crisis these freshwater planarians apparently were not able to cross the sea barrier between Crete and the mainland, while they probably did disperse between islands in the Aegean Sea. Their dependence on freshwater to survive suggests the presence of contiguous freshwater bodies in those regions. Our results also suggest a major extinction of freshwater planarians on the Peloponnese at the end of the Pliocene, while about 2 Mya ago, when the current Mediterranean climate was established, these Peloponnese populations probably began to disperse again. At the end of the Pliocene or during the Pleistocene, mainland populations of Dugesia colonized the western coast, including the Ionian Islands, which were then part of the continent.
T. B. Reynoldson - One of the best experts on this subject based on the ideXlab platform.
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the status of Dugesia lugubris and d polychroa turbellaria tricladida in britain
Journal of Zoology, 2009Co-Authors: T. B. Reynoldson, L S BellamyAbstract:Two types of triclad in the Dugesia lugubris species complex were identified on the basis of head shape and cannibalistic behaviour. More detailed examination of the reproductive organs, breeding and cytology showed them to be distinct species. One of them fitted the description of Dugesia lugubris (sensu Schmidt, 1860), the other fitted D. polychroa (sensu Schmidt, 1862). They are most reliably distinguished by the features of the penial papilla; in D. polychroa it is relatively small, with a ventral duct and lacking a permanent nipple, and in D. lugubris the papilla is massive, with an ejaculatory duct surrounded by thick musculature and possessing a permanent nipple. There are also differences in external appearance. The head of D. lugubris is pointed, that of D. polychroa rounded. The eyes are nearer the anterior border of the head in the former. Dugesia lugubris has a less pronounced neck and a more squat appearance than D. polychroa and is often larger. The colour and pattern of pigment is more variable in D. polychroa. The ventral surface is lighter in colour than the dorsal in D. polychroa, but in D. lugubris they are similar. It is suggested that the earlier confusion in the nomenclature of these two species was due to the failure to recognize that D. polychroa may exhibit a temporary nipple on the penial papilla. A survey of lakes in northern Britain shows that Dugesia polychroa is more common than D. lugubris. The karyotype of D. polychroa corresponds to Benazzi's type B, while that of D. lugubris belongs to type E. Most of the earlier records and literature for British Dugesia refer to D. polychroa.
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continuing dispersal of freshwater triclads platyhelminthes turbellaria in britain with particular reference to lakes
Freshwater Biology, 1999Co-Authors: J. O. Young, T. B. ReynoldsonAbstract:1. A survey of lakes in Anglesey and Snowdonia, Wales, in the summer of 1997 recorded changes in the triclad fauna which had occurred since earlier studies in the 1950s and in 1973. Two native species, Polycelis tenuis and Dugesia polychroa, and two immigrants, Planaria torva and especially Dugesia tigrina, have increased their range. The triclad fauna has remained unchanged with time in eleven out of sixteen lakes in Snowdonia, in contrast to only one out of fourteen lakes on Anglesey. This supports the hypothesis produced in the 1950s, that the triclad fauna of the ion-poor, unproductive lakes in Snowdonia would change little with time, being maintained by ecological interactions, whereas the ion-rich, productive lakes on Anglesey, from which native Dugesia spp. and Dendrocoelum lacteum are historically absent, would increase in triclad diversity. 2. An examination of national records for the distribution of D. tigrina and Pl. torva indicated their continuing dispersal in both still and running waters in mainland Britain, with the former species having the greater frequency of occurrence. 3. The reasons for this may be that D. tigrina is (a) more easily dispersed, (b) a more opportunistic, catholic feeder, (c) a more vigorous competitor, (d) able to reproduce asexually and (e) able to prey to some extent on other triclad species, as shown in the laboratory but not yet confirmed in the field. The absence of D. tigrina and Pl. torva from unproductive lakes may be explained in terms of low temperature and feeding mode, and a low standing crop of gastropods, respectively. 4. Seven surveys (1961–1997) of the triclad fauna (six species) of Colemere, England, revealed that D. tigrina was confined to one small area of the littoral zone until the mid-1980s, after which it spread fairly rapidly to occupy the entire shore by 1997. Its expansion has been to the detriment of all the native species, particularly P. tenuis, except Dd. lacteum. The possible extinction of Pl. torva may be linked to a numerical reduction in snails, particularly Potamopyrgus jenkinsi. 5. Dugesia tigrina has an adverse effect on the native triclad fauna in lakes, particularly when only a few species are present. This has been explained in terms of the availability of a wider variety of food. The presence of a larger number of triclad species denies the immigrant food items, particularly crustaceans and snails, the food refuges of Dd. lacteum and Dugesia spp., respectively. However, the long-term study of Colemere has shown that more diverse triclad faunas may also be vulnerable to this immigrant. The effect of Pl. torva on native triclads remains uncertain.
