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SCANNING ELECTRON MICROSCOPY OF THECAE OF THE DINOFLAGELLATE GENUS ORNITHOCERCUS 1
Author(s) -
Taylor F. J. R.
Publication year - 1971
Publication title -
journal of phycology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.85
H-Index - 127
eISSN - 1529-8817
pISSN - 0022-3646
DOI - 10.1111/j.1529-8817.1971.tb01510.x
Subject(s) - biology , dinoflagellate , genus , ultrastructure , anatomy , wing , evolutionary biology , crystallography , botany , physics , chemistry , thermodynamics
SUMMARY Members of the genus Ornithocercus are all tropical oceanic species in which the theca is extended in the form of elaborate wing‐like projections, the lists, supported by ribs. This paper illustrates the topography of 6 of the species. The theca is penetrated by numerous simple pores opening flush with the outer surface. On the inner side of the thecae the pores have a raised rim. The hypotheca of all species examined except O. splendidus have shallow depressions, the areolae, over most of the surface. Secondary thickening of mature cell walls deepens the appearance of the areolae, and increases their extent over the hypotheca in O. quadratus. The number of pores is not directly correlated with the areolae but seems rather to be a function of cell size. A comparison of the surface features confirms views that O. splendidus occupies a relatively isolated phenetic position. It also confirms the close similarity of O. steinii with O. thumii. Unexpectedly it suggested a phenetic closeness between O. magnificus and O. quadratus on the basis of hypothecal structure and rib features of the left sulcal list. O. heteroporus could not be subjected to the same degree of study and its position cannot be commented on. Some theoretical hydrodynamic and morphogenetic problems in Ornithocercus are discussed.