Die Feinstruktur der Zellw�nde bei Mesotaeniaceae und Gonatozygaceae mit einer vergleichenden Betrachtung der verschiedenen Wandtypen der Conjugatophyceae und �ber deren systematischen Wert

Phylogeny ofGonatozygonandGenicularia(Gonatozygaceae, Desmidiales) based onrbcL sequences

“…Sequencing primers included the aforementioned (1986) X04465 Genera in the Zygnematales are assigned to families according to Brook (I981) and Mix (1972Mix ( , 1973 …”

“…Genicularia has 2 or 3 parietal, spiral ribbonshaped chloroplasts; Gonatozygon has 1 or 2 axial chloroplasts that are flattened or stellate in cross-section (Prescott et al, 1972;Mix, 1973). Originally described by investigators as lacking pores, both genera have pores in the outer wall layer that are simpler in structure than those of the Desmidiaceae (Mix, 1972(Mix, , 1973(Mix, , 1980. The cell wall in both genera is usually densely covered with scattered granules (Prescott et al, 1972;Mix, 1972Mix, , 1973Mix, , 1980Gerrath, 1993).…”

“…Originally described by investigators as lacking pores, both genera have pores in the outer wall layer that are simpler in structure than those of the Desmidiaceae (Mix, 1972(Mix, , 1973(Mix, , 1980. The cell wall in both genera is usually densely covered with scattered granules (Prescott et al, 1972;Mix, 1972Mix, , 1973Mix, , 1980Gerrath, 1993). These cell wall features represent an intermediate condition between the unsegmented, smooth walls of the Zygnemataceae (unbranched filamentous forms) and Mesotaeniaceae (saccoderm desmids) and the elaborately sculptured, pore-laden walls of the Desmidiaceae (placoderm desmids).…”

“…Several later authors also viewed these two genera as saccoderm desmids (Smith, 1950;Prescott et aI., 1972). However, recent classifications, based on the electron microscopic structure of the cell wall and the sculpting and pore structure of the outer layers (Mix, 1972(Mix, , 1973Mix eta]., 1982), have confirmed the placement of this pair of genera in a separate family related to placoderm desmids (Oltmanns, 1922;West & Fritsch, 1927;Fritsch, 1935;Prescott, 1948). Kouwets & Coesel (1984) concluded that because of similarities in cell wall structure, Gonatozygon and Genicularia should be placed with Penium (excluding taxa transferred to Actinotaenium: Kouwets & Coesel, 1984) in the family Peniaceae.…”

“…On the basis of the ultrastructure of the cell wall in Gonatozygon and Genicularia, which have moderately sculpted walls and simple pores (Mix, 1972;Kouwets & Coesel, 1984), we hypothesized that Gonatozygon and Genicularia are monophyletic (i.e. sister taxa).…”