Type genus:Aclistochara Peck,1937 emend.Peck,1957 Diagnosis:Gyrogonites composed of five sinistral spiral cells,apicalpart truncated or contracted forming a short neck,summits flat.Spiralcells become distinctly thinne...Type genus:Aclistochara Peck,1937 emend.Peck,1957 Diagnosis:Gyrogonites composed of five sinistral spiral cells,apicalpart truncated or contracted forming a short neck,summits flat.Spiralcells become distinctly thinner and narrower in the apical periphery,formingapical peripheral depression of various depths.The apical centre is eithermarked by an apical rosette formed by inflation of spital ends,orl thin andflat when the spiral ends are not inflated,without apical orifice and utricle.展开更多
文摘Type genus:Aclistochara Peck,1937 emend.Peck,1957 Diagnosis:Gyrogonites composed of five sinistral spiral cells,apicalpart truncated or contracted forming a short neck,summits flat.Spiralcells become distinctly thinner and narrower in the apical periphery,formingapical peripheral depression of various depths.The apical centre is eithermarked by an apical rosette formed by inflation of spital ends,orl thin andflat when the spiral ends are not inflated,without apical orifice and utricle.
