Members of the genus Hypotrichidium are adapted to a planktonic lifestyle and are characterized among hypotrichs by their unique pyriform body with pointed tail and spiral cirral rows around the whole body.During a su...Members of the genus Hypotrichidium are adapted to a planktonic lifestyle and are characterized among hypotrichs by their unique pyriform body with pointed tail and spiral cirral rows around the whole body.During a survey of Korean freshwater ciliates,we discovered a new Hypotrichidium species that changes its cortical granules color.Observations on the morphology and behavior of Hypotrichidium bichromum n.sp.revealed several other unusual features such as the polymorphic life cycle and cannibalistic behavior.When grown in a fresh culture,wellnourished specimens are characterized by a pyriform body,yellow cortical granules,and two macronuclear nodules.In declining cultures,two morphologically different morphs occur,both with ruby-red cortical granules:(1)a well-nourished morph with a pyriform body and 2–4 macronuclear nodules,which shows a cannibalistic behavior feeding on other well-nourished cells,encysting cells,and reorganizers;(2)a fast-swimming,nonfeeding morph with slender body,two macronuclear nodules,and highly degenerated undulating membranes.The complete ontogenetic process of the new species is described to show the origin of each structure.Moreover,phylogenetic analyses based on 18S rRNA gene sequences show that the new species is placed in a clade containing sequences of three congeners.展开更多
基金supported by a grant from the Nakdonggang National Institute of Biological Resources(NNIBR)funded by the Ministry of Environment(MOE)of the Republic of Korea(NNIBR20241105)by the National Research Foundation of Korea(NRF)grant(No.RS-2023-00209201)funded by the Korea government(MSIT).
文摘Members of the genus Hypotrichidium are adapted to a planktonic lifestyle and are characterized among hypotrichs by their unique pyriform body with pointed tail and spiral cirral rows around the whole body.During a survey of Korean freshwater ciliates,we discovered a new Hypotrichidium species that changes its cortical granules color.Observations on the morphology and behavior of Hypotrichidium bichromum n.sp.revealed several other unusual features such as the polymorphic life cycle and cannibalistic behavior.When grown in a fresh culture,wellnourished specimens are characterized by a pyriform body,yellow cortical granules,and two macronuclear nodules.In declining cultures,two morphologically different morphs occur,both with ruby-red cortical granules:(1)a well-nourished morph with a pyriform body and 2–4 macronuclear nodules,which shows a cannibalistic behavior feeding on other well-nourished cells,encysting cells,and reorganizers;(2)a fast-swimming,nonfeeding morph with slender body,two macronuclear nodules,and highly degenerated undulating membranes.The complete ontogenetic process of the new species is described to show the origin of each structure.Moreover,phylogenetic analyses based on 18S rRNA gene sequences show that the new species is placed in a clade containing sequences of three congeners.
