During a helminthological study of waterfowl in China,a new species(Cloacotaenia cygnimorbus sp.nov.)of hymenolepidid cestodes(tapeworm)was found in the small intestine of whooper swan(Cygnus cygnus,Linnaeus,1758).The...During a helminthological study of waterfowl in China,a new species(Cloacotaenia cygnimorbus sp.nov.)of hymenolepidid cestodes(tapeworm)was found in the small intestine of whooper swan(Cygnus cygnus,Linnaeus,1758).The rudimentary rostellum and four unarmed muscular suckers,proglottids with distinct craspedote and three spherical testes were coincident with the characters of Cloacotaenia or Hymenolepis,but phylogenetic analysis of 28S rRNA and cox1 gene revealed that the new species is Cloacotaenia rather than Hymenolepis.Its morphology was also clearly diff erentiated from C.megalops in the arrangement of its testes in a triangle instead of in line and the cirrus unarmed rather than spined.Compared with C.megalops,the new species has more elongated neck,much larger mature proglottids and much smaller testes,cirrus sac,ovary,vitellarium and uterine proglottid.In addition,it infected the host intestine not the cloacae.Phylogenetic analysis of cox1 gene of the new species shows that it had a level of sequence variation(10.52–23.06%)with the sequences of C.megalops.The considerable morphological and molecular diff erences between those two parasites support C.cygnimorbus sp.nov.as a new species.展开更多
Molecular identification methods,in particular high-throughput sequencing tools,have greatly improved our knowledge about fungal diversity and biogeography,but many of the recovered taxa from natural environments cann...Molecular identification methods,in particular high-throughput sequencing tools,have greatly improved our knowledge about fungal diversity and biogeography,but many of the recovered taxa from natural environments cannot be identified to species or even higher taxonomic levels.This study addresses the phylogenetic placement of previously unrecognized fungal groups by using two complementary approaches:(i)third-generation amplicon sequencing analysis of DNA from global soil samples,screening out ITS reads of<90%similarity to other available Sanger sequences,and(ii)analysis of common fungal taxa that were previously indicated to be enigmatic in terms of taxonomic placement based on the ITS sequences alone(so-called top50 sequences).For the global soil samples,we chose to amplify the full rRNA gene operon using four partly overlapping amplicons and multiple newly developed primers or primer combinations that cover nearly all fungi and a vast majority of non-fungal eukaryotes.We extracted the rRNA 18S(SSU)and 28S(LSU)genes and performed phylogenetic analyses against carefully selected reference material.Both SSU and LSU analyses placed most soil sequences and top50 sequences to known orders and classes,but tens of monophyletic groups and single sequences remained outside described taxa.Furthermore,the LSU analyses recovered a few small groups of sequences that may potentially represent novel phyla.We conclude that rRNA genes-based phylogenetic analyses are efficient tools for determining phylogenetic relationships of fungal taxa that cannot be placed to any order or class using ITS sequences alone.However,in many instances,longer rRNA gene sequences and availability of both SSU and LSU reads are needed to improve taxonomic resolution.By leveraging third-generation sequencing from global soil samples,we successfully provided phylogenetic placement for many previously unidentified sequences and broadened our view on the fungal tree of life,with 10-20%new order-level taxa.In addition,the PacBio sequence data greatly extends fungal class-level information in reference databases.展开更多
基金Thanks are especially due to Professor David Blair of the School of Marine and Tropical Biology,James Cook University,Professor Jean Mariaux,Natural History Museum in Geneva,Switzerland,and reviewers for assistance with the morphological description and language editing.
文摘During a helminthological study of waterfowl in China,a new species(Cloacotaenia cygnimorbus sp.nov.)of hymenolepidid cestodes(tapeworm)was found in the small intestine of whooper swan(Cygnus cygnus,Linnaeus,1758).The rudimentary rostellum and four unarmed muscular suckers,proglottids with distinct craspedote and three spherical testes were coincident with the characters of Cloacotaenia or Hymenolepis,but phylogenetic analysis of 28S rRNA and cox1 gene revealed that the new species is Cloacotaenia rather than Hymenolepis.Its morphology was also clearly diff erentiated from C.megalops in the arrangement of its testes in a triangle instead of in line and the cirrus unarmed rather than spined.Compared with C.megalops,the new species has more elongated neck,much larger mature proglottids and much smaller testes,cirrus sac,ovary,vitellarium and uterine proglottid.In addition,it infected the host intestine not the cloacae.Phylogenetic analysis of cox1 gene of the new species shows that it had a level of sequence variation(10.52–23.06%)with the sequences of C.megalops.The considerable morphological and molecular diff erences between those two parasites support C.cygnimorbus sp.nov.as a new species.
基金funded by the Estonian Science Foundation(Grants PUT1399,PRG632,MOBERC21)。
文摘Molecular identification methods,in particular high-throughput sequencing tools,have greatly improved our knowledge about fungal diversity and biogeography,but many of the recovered taxa from natural environments cannot be identified to species or even higher taxonomic levels.This study addresses the phylogenetic placement of previously unrecognized fungal groups by using two complementary approaches:(i)third-generation amplicon sequencing analysis of DNA from global soil samples,screening out ITS reads of<90%similarity to other available Sanger sequences,and(ii)analysis of common fungal taxa that were previously indicated to be enigmatic in terms of taxonomic placement based on the ITS sequences alone(so-called top50 sequences).For the global soil samples,we chose to amplify the full rRNA gene operon using four partly overlapping amplicons and multiple newly developed primers or primer combinations that cover nearly all fungi and a vast majority of non-fungal eukaryotes.We extracted the rRNA 18S(SSU)and 28S(LSU)genes and performed phylogenetic analyses against carefully selected reference material.Both SSU and LSU analyses placed most soil sequences and top50 sequences to known orders and classes,but tens of monophyletic groups and single sequences remained outside described taxa.Furthermore,the LSU analyses recovered a few small groups of sequences that may potentially represent novel phyla.We conclude that rRNA genes-based phylogenetic analyses are efficient tools for determining phylogenetic relationships of fungal taxa that cannot be placed to any order or class using ITS sequences alone.However,in many instances,longer rRNA gene sequences and availability of both SSU and LSU reads are needed to improve taxonomic resolution.By leveraging third-generation sequencing from global soil samples,we successfully provided phylogenetic placement for many previously unidentified sequences and broadened our view on the fungal tree of life,with 10-20%new order-level taxa.In addition,the PacBio sequence data greatly extends fungal class-level information in reference databases.
