Ultrastructure and Ecology of Calycomonas ovalis Wulff, 1919, (Chrysophyceae) and Its Redescription as a Testate Rhizopod, Paulinella ovalis N. Comb. (Filosea: Euglyphina)1

An exceptional bloom (109 cells/liter) of a unicellular alga, Aureococcus anophagefferens, in Narragansett Bay, RI, was accompanied by unusually high numbers (6 times 106 tests/liter) of vase-shaped cells of Calycomonas ovalis Wulff, hitherto considered a flagellated chrysophyte. Phase contrast light microscopy showed the characteristic oval lorica or test of C. ovalis, ca. 3.0 times 4.5 μm. Transmission electron microscopy of thin sections of natural populations revealed, however, that C. ovalis is actually a rhizopod within a test of electron-dense scales. This estuarine, planktonk testacean extends a pseudopodium through a narrow pseudostome and lacks chloroplasts or flagella. It is a bacterivore and feeds primarily on unicellular cyanobacteria. The morphology, ultrastructure, and cell division of C. ovalis are described. These characteristics place C. ovalis with the genus Paulinella (Sarcodina: Filosea: Euglyphina), which at present contains the single species, P. chromatophora Lauterbom. Calycomonas ovalis is thus assigned to Paulinella as P. ovalis n. comb.

[1]  Paul W. Johnson,et al.  ULTRASTRUCTURE AND ECOLOGY OF AUREOCOCCUS ANOPHAGEFERENS GEN. ET SP. NOV. (CHRYSOPHYCEAE): THE DOMINANT PICOPLANKTER DURING A BLOOM IN NARRAGANSETT BAY, RHODE ISLAND, SUMMER 1985 1 , 1988 .

[2]  M. Coûteaux,et al.  The biology and ultrastructure of the soil testate amoeba Tracheleuglypha dentata (Rhizopoda: Euglyphidae). , 1987, European journal of protistology.

[3]  O. Anderson.  Fine Structure of a Silica‐Biomineralizing Testate Amoeba, Netzelia tuberculata1 , 1987 .

[4]  G. Espeland,et al.  Flagellates from Kilsfjorden, southern Norway, with description of two new species of Choanoflagellida , 1986 .

[5]  M. Sieracki,et al.  Estimating plankton populations with the Apple II , 1985 .

[6]  Paul W. Johnson,et al.  IN‐SITU MORPHOLOGY AND OCCURRENCE OF EUCARYOTIC PHOTOTROPHS OF BACTERIAL SIZE IN THE PICOPLANKTON OF ESTUARINE AND OCEANIC WATERS 1 , 1982 .

[7]  Mary Parke,et al.  Check-list of British marine algae-third revision , 1968, Journal of the Marine Biological Association of the United Kingdom.

[8]  N. Marshall,et al.  Role of the Coastal and Upper Estuarine Waters Contributing Phytoplankton to the Shoals of the Niantic Estuary , 1965 .

[9]  E. M. Hulburt.  FLAGELLATES FROM BRACKISH WATERS IN THE VICINITY OF WOODS HOLE, MASSACHUSETTS 1 , 1965 .

[10]  R. Norris.  Studies on Phytoplankton in Wellington Harbour , 1964 .

[11]  J. Lackey.  SOME FRESH WATER PROTOZOA WITH BLUE CHROMATOPHORES , 1936 .

[12]  A. Boucot,et al.  Paulinella nov. gen., new Devonian terebratuloid (Brachiopoda) from Europe , 1987 .

[13]  Von Helmut Pankow.  Paulinella chromatophoraLauterb., eine bisher nur im Süßwasser nachgewiesene Thekamöbe, in den Boddengewässern des Darß and des Zingst (südliche Ostsee) , 1982 .

[14]  B. Leadbeater,et al.  Ultrastructure and Deposition of Silica in the Chrysophyceae , 1981 .

[15]  E. Bovee.  Distribution and Forms of Siliceous Structures Among Protozoa , 1981 .