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Biology Letters Sep 2019Understanding biological diversity is crucial for ecological and evolutionary studies. Even though a great part of animal diversity has already been documented, both...
Understanding biological diversity is crucial for ecological and evolutionary studies. Even though a great part of animal diversity has already been documented, both morphological surveys and metabarcoding analyses have previously shown that some animal groups, such as Platyhelminthes, may harbour hidden diversity. To better understand the molecular diversity of Platyhelminthes, one of the most diverse and biomedically important animal phyla, we here combined data from six marine and two freshwater metabarcoding expeditions that cover a broad variety of aquatic habitats and analysed the data by phylogenetic placement. Our results show that a great part of the hidden diversity is located in early-branching clades such as Catenulida and Macrostomorpha, as well as in late-diverging clades such as Proseriata and Rhabdocoela. We also report the first freshwater record of Gnosonesimida, a group previously thought to be exclusively marine. Finally, we identified two putative novel freshwater Platyhelminthes clades that branch between well-defined orders of the phylum. Thus, our analyses of several environmental datasets confirm that a large part of the diversity of Platyhelminthes remains undiscovered, point to groups with more potential novel species and identify freshwater environments as potential reservoirs for novel species of flatworms.
Topics: Animals; Biodiversity; Biological Evolution; Fresh Water; Phylogeny; Platyhelminths
PubMed: 31506037
DOI: 10.1098/rsbl.2019.0182 -
International Journal For Parasitology Dec 1994Symbiotic associations have arisen independently in several groups of the largely free-living turbellarians. Morphological adaptations of turbellarians to a symbiotic...
Symbiotic associations have arisen independently in several groups of the largely free-living turbellarians. Morphological adaptations of turbellarians to a symbiotic way of life include suckers and adhesive glands for attachment, elaborate systems of microvilli and other epidermal structures for absorption of food, glands for the formation of cysts, cocoons and cement material, and lack of a pharynx and intestine in some species. However, many species closely resemble their free-living relatives. Egg production is greatly increased at least in some species, and life cycles are always direct. Food of symbiotic turbellarians consists of host food and/or host tissue. Ectosymbiotes show fewer physiological adaptations than entosymbiotes. The major groups of parasitic Platyhelminthes (Trematoda Aspidogastrea, Trematoda Digenea, Monogenea, Udonellidea, Cestoda including Gyrocotylidea, Amphilinidea and Eucestoda), form one monophylum, the Neodermata, characterized by a neodermis (tegument) replacing the larval epidermis, epidermal cilia with a single horizontal rootlet, sensory receptors with electron-dense collars, spermatozoa with axonemes incorporated in the sperm body by proximodistal fusion, and protonephridial flame bulbs formed by two cells each contributing a row of longitudinal ribs to the filtration apparatus. The sister group of the Neodermata is unknown but is likely to be a large taxon including the Proseriata and some other turbellarian groups. Among the Neodermata, the Aspidogastrea is likely to be the most archaic group, as indicated by DNA studies, morphology, life cycles and physiology. Aspidogastreans can survive for many days or even weeks outside a host in simple media, they show little host specificity, and have an astonishingly complex nervous system and many types of sensory receptors, both in the larva and the adult. It is suggested that Aspidogastrea were originally parasites of molluscs (and possibly arthropods and other invertebrates) and that they are archaic forms which have remained at a stage where vertebrates represent facultative hosts or obligatory final hosts into which only the very last stages of the life cycle (maturation of the gonads) have been transferred. The complex life cycles of Digenea have evolved from the simple aspidogastrean ones by intercalation of multiplicative larval stages (sporocysts, rediae) in the mollusc host, and of cercarial stages ensuring dispersal to the now obligatory final host. Monogenea may have lost the molluscan host or evolved before the early neodermatans had acquired it. Cestoda either replaced the original molluscan with an arthropod host, retained an original arthropod host or evolved from an early neodermatan before molluscan hosts had been acquired, newly acquiring an arthropod host.(ABSTRACT TRUNCATED AT 400 WORDS)
Topics: Animals; Biological Evolution; Cestode Infections; Fishes; Host-Parasite Interactions; Larva; Microscopy, Electron; Models, Biological; Nervous System; Platyhelminths; Sensory Receptor Cells; Snails; Symbiosis; Trematode Infections; Turbellaria
PubMed: 7729971
DOI: 10.1016/0020-7519(94)90185-6 -
Journal of Helminthology Nov 2022(Gusev, ) Gusev, was collected from the so-iuy mullet (Temminck & Schlegel, 1845) from the Black Sea and the Sea of Japan. DNA sequences data for , as well as its...
First morphological and phylogenetic data on (Platyhelminthes: Monogenea) from the Black Sea and the Sea of Japan and molecular evidence of deep divergence of sympatric species parasitizing .
(Gusev, ) Gusev, was collected from the so-iuy mullet (Temminck & Schlegel, 1845) from the Black Sea and the Sea of Japan. DNA sequences data for , as well as its morphological characters from the Sea of Japan were obtained for the first time. Significant morphometric and genetic diversity between specimens of from the Black-Azov Sea region and the Sea of Japan were not found. For the first time, the molecular phylogeny of based on three fragments of the nuclear DNA ribosomal cluster (18S, internal transcribed spacer 1 and 28S) was reconstructed. Molecular analysis of species from the Atlantic and Pacific Oceans revealed a significant phylogenetic distance between and two others species ( and ) from the same host () and region. This result indicates the lack of correspondence between the phylogenetic and geographical closeness of the hosts and the relation of their parasites from the genus .
Topics: Animals; Phylogeny; Black Sea; Japan; Platyhelminths; Trematoda; Smegmamorpha
PubMed: 36377340
DOI: 10.1017/S0022149X22000724 -
Parasitology International Apr 2022An integrative study was performed to understand the phylogenetic relationships of an undescribed, freshwater species of microcotylid parasitizing Plagioscion...
Morphology and molecular phylogeny of Pauciconfibuloides amazonica gen. n. sp. n. (Platyhelminthes, Monogenoidea) parasitizing the Amazonian croaker Plagioscion squamosissimus.
An integrative study was performed to understand the phylogenetic relationships of an undescribed, freshwater species of microcotylid parasitizing Plagioscion squamosissimus from the Amazon River Basin. Based on morphological and molecular analysis (18S rDNA and partial 28S rDNA genes), a new genus is proposed to accommodate this new species, Pauciconfibuloides amazonica gen. n. sp. n. The new genus is closely related to Protastomicrocotylinae and Pauciconfibula by sharing the vagina, male copulatory organ, and genital atrium all unarmed. However, Pauciconfibuloides gen. n. can be distinguished from those taxa by the prostatic system and position of the vaginal pore. Molecular phylogenetic inference suggests a sister relationship with species of Polylabris (Prostatomicrocotylinae), but to date, there are no available 18S or 28S rDNA sequences of Pauciconfibula to be compared. This is the first report of a microcotylid parasitizing a freshwater sciaenid from South America.
Topics: Animals; DNA, Ribosomal; Female; Fish Diseases; Male; Perciformes; Phylogeny; Platyhelminths; Trematoda
PubMed: 34737075
DOI: 10.1016/j.parint.2021.102489 -
Zootaxa Feb 2021Bradynectes ensifer is a new species of Macrostomorpha from shallow subtidal sediment in Bogue Inlet, NC, USA. It differs primarily from all other named members of the...
Bradynectes ensifer is a new species of Macrostomorpha from shallow subtidal sediment in Bogue Inlet, NC, USA. It differs primarily from all other named members of the genus in the radically different shape of its copulatory stylet. We also consider historical records of currently unnamed specimens with similar stylet morphology collected from the NC coast by the late Dr. Reinhard M. Rieger and his students.
Topics: Animals; Bays; North Carolina; Platyhelminths
PubMed: 33756696
DOI: 10.11646/zootaxa.4927.4.10 -
Zootaxa Mar 2021The taxon Koinocystididae is the third most species-rich family within Eukalyptorhynchia. However, its diversity and phylogeny have been largely neglected in former...
The taxon Koinocystididae is the third most species-rich family within Eukalyptorhynchia. However, its diversity and phylogeny have been largely neglected in former studies. We introduce three new genera and twelve new species of Koinocystididae including Simplexcystis asymmetrica gen. n. sp. n., Galapagetula cubensis sp. n., eight species of Reinhardorhynchus gen. n. and two species of Itaipusa. This raises the total number of species within Koinocystididae from 51 to 63. We also report on new distribution records for six known species: I. divae (Cuba, Panama and New Caledonia), I. karlingi (Sardinia and Lanzarote), Reinhardorhynchus riegeri comb. n. (Cuba), R. ruffinjonesi comb. n. (Cuba and Panama), Utelga heinckei (Cuba and Lanzarote), and U. pseudoheinckei (Sardinia). Simplexcystis asymmetrica gen. n. sp. n. is characterised by a male duct running eccentrically through the copulatory bulb, lack of any hard structures in the male system, lack of a bursa, and the fact that the epithelia of the female, the male, and part of the common atrium are covered by a brush border. Galapagetula cubensis sp. n. has a caudal gonopore, a divisa-type copulatory bulb with an unarmed penis papilla, and a female duct without a sphincter. The new species of Itaipusa and Reinhardorhynchus gen. n. differ from their congeners in the detailed structure of the copulatory bulb and especially the hard structures associated with it. In a molecular phylogenetic analysis based on all available 18S and 28S rDNA sequences of koinocystidids, we found support for the monophyly of the family and the genus Utelga Marcus, 1949. The genus Itaipusa is not monophyletic in that I. sinensis forms a clade with Rhinolasius dillonicus, while other species of Itaipusa that have a copulatory bulb armed with hooks form a clade together with Sekerana stolzi. As the type species of Itaipusa (I. divae) is in neither of these clades, we erected a new genus for I. sinensis (Koinogladius gen. n.) and one for species of Itaipusa having a hook-bearing copulatory bulb (Reinhardorhynchus gen. n.), respectively. Whether the remaining species of Itaipusa form a monophylum remains uncertain.
Topics: Animals; Female; Male; Phylogeny; Platyhelminths
PubMed: 33757005
DOI: 10.11646/zootaxa.4948.4.1 -
PloS One 2022Tiny animals in various metazoan phyla inhabit the interstices between sand and/or gravel grains, and adaptive traits in their body plan, such as simplification and size...
Reversible shifts between interstitial and epibenthic habitats in evolutionary history: Molecular phylogeny of the marine flatworm family Boniniidae (Platyhelminthes: Polycladida: Cotylea) with descriptions of two new species.
Tiny animals in various metazoan phyla inhabit the interstices between sand and/or gravel grains, and adaptive traits in their body plan, such as simplification and size reduction, have attracted research attention. Several possible explanations of how such animals colonized interstitial habitats have been proposed, but their adaptation to this environment has generally been regarded as irreversible. However, the actual evolutionary transitions are not well understood in almost all taxa. In the present study, we show reversible evolutionary shifts from interstitial to epibenthic habitats in the lineage of the polyclad flatworm genus Boninia. In addition, we establish two new species of this genus found from different microhabitats on a single beach in Okinawa Island, Japan: (i) the interstitial species Boninia uru sp. nov. from gravelly sediments and (ii) the epibenthic species Boninia yambarensis sp. nov. from rock undersurfaces. Our observations suggest that rigid microhabitat segregation exists between these two species. Molecular phylogenetic analyses based on the partial 18S and 28S rDNA sequences of the new Boninia species and four other congeners, for which molecular sequences were available in public databases [Boninia antillara (epibenthic), Boninia divae (epibenthic), Boninia neotethydis (interstitial), and an unidentified Boninia sp. (habitat indeterminate)], revealed that the two interstitial species (B. neotethydis and B. uru sp. nov.) were not monophyletic among the three epibenthic species. According to ancestral state reconstruction analysis, the last common ancestor of the analyzed Boninia species inhabited interstitial realms, and a shift to the epibenthic environment occurred at least once. Such an "interstitial to noninterstitial" evolutionary route seems to be rare among Animalia; to date, it has been reported only in acochlidian slugs in the clade Hedylopsacea. Our phylogenetic tree also showed that the sympatric B. uru sp. nov. and B. yambarensis sp. nov. were not in a sister relationship, indicating that they colonized the same beach independently rather than descended in situ from a common ancestor that migrated and settled at the beach.
Topics: Animals; Platyhelminths; Phylogeny; Biological Evolution; Ecosystem; DNA, Ribosomal
PubMed: 36417389
DOI: 10.1371/journal.pone.0276847 -
Journal of Morphology Apr 2021Prolecithophora is a poorly studied flatworm order belonging to the adiaphanidan clade, together with Tricladida and Fecampiida. The phylogenetic position of the three...
Prolecithophora is a poorly studied flatworm order belonging to the adiaphanidan clade, together with Tricladida and Fecampiida. The phylogenetic position of the three orders within this clade is not yet resolved. Additionally, no obvious synapomorphy other than an opaque epidermis could be found so far. In this study, the serotonergic nervous system of six different prolecithophoran species has been studied for the first time with a fluorescent immunocytochemical technique. We found that all six species show a similar pattern of the serotonergic nervous system. The typical prolecithophoran serotonergic nervous system consists of a cephalic ganglion in the anterior body part from which a pair of dorsal, ventral, and lateral longitudinal nerve cords originate. Furthermore, the three longitudinal nerve cords of one body side are connected to each other at the posterior body part by a conspicuous commissure. The ventral cords, which we consider the main cords, are most prominent and show double brain roots. A comparison of the nervous system within Adiaphanida shows clearly that prolecithophorans and fecampiids are much more similar in this regard than prolecithophorans and triclads.
Topics: Animals; Brain; Nerve Tissue; Nervous System; Phylogeny; Platyhelminths; Serotonin
PubMed: 33569841
DOI: 10.1002/jmor.21332 -
Journal of the American Medical Women's... Jan 1948
Topics: Animals; Humans; Platyhelminths; Tropical Medicine
PubMed: 18905372
DOI: No ID Found -
Molecular and Biochemical Parasitology Jul 2020Codon usage bias (CUB) is the nonrandom usage of synonymous codons in which some codons are more preferred to others.CUB can be determined by mutation pressure and...
Codon usage bias (CUB) is the nonrandom usage of synonymous codons in which some codons are more preferred to others.CUB can be determined by mutation pressure and selection. Various approaches have been used to understand the pattern of CUB in the mitochondrial ND (MT-ND or ND) genes involved in complex I of respiratory chain in five different classes of Platyhelminthes as no work was reported yet. The present study revealed that the CUB varies across MT-ND genes and the coding sequences showed the richness of A and T. Correspondence analysis implied the effect of mutational pressure and also the pattern of codon usage was different in different classes of platyhelminthes for MT-ND genes. Highly significant correlation was observed between overall nucleotide composition and its 3rd codon position in most of the homogeneous nucleotides such as A% and A3%, T% and T3%, G% and G3%, C% and C3%, GC% and GC3% and also some significant correlations observed among heterogeneous nucleotides in all the five classes for MT-ND genes suggested the role of mutational pressure as well as natural selection in affecting the CUB. Neutrality plot suggested that the contributions of natural selection and mutational pressure varied across different classes of platyhelminthes and also differed in different MT-ND genes.
Topics: Animals; Base Composition; Codon Usage; Computational Biology; Electron Transport Complex I; Genes, Helminth; Genes, Mitochondrial; Mutation; Nucleotides; Phylogeny; Platyhelminths; Selection, Genetic; Species Specificity
PubMed: 32592756
DOI: 10.1016/j.molbiopara.2020.111294