Ref ID : 7107
Hara Shigemitsu and Takahashi Eiji; An Investigation with Electron Microscope of Marine Choanoflagellates (Protozoa: Choanoflagellida) from Osaka Bay, Japan I. Re-investigation of Bicosta spinifera, B. minor and Crucispina cruciformis. Bulletin of Plankton Society of Japan 34(1):1-13, 1987
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Notes
The choanoflagellates, Bicosta spinifera, B. minor and Crucispina cruciformis were reexamined. In B. spinifera: (1) the lorica is longer than 55 µm, (2) the posterior spine is longer than the anterior ones, and (3) the longitudinal costae twist in "sinistrorsum externe visus" and cross at the level of the costal strips of the anterior lorica chamber. In B. minor: (1) the lorica is smaller than 45 µm, (2) the posterior spine is shorter than the anterior ones, and (3) the longitudinal costae either do not twist at all or twist in "dextrorsum externe visus" and cross at the level of the costal strips of the posterior lorica chamber. The twisting of longitudinal costae itself is not the species specific characteristic of B. spinifera. The process of replication of the lorica was also observed in B. minor. There is a preordinated sequence of formation of costal strips: the costal strips of the anterior lorica chamber are formed first and followed by the posterior ones, next the anterior spines and the posterior spine at last. These costal strips in the mother protoplast are oriented in the opposite direction to the corresponding costal strips of the mother lorica. In Crucispina cruciformis, the lengths of the costal strips forming the anterior and posterior spines vary correlatively to the water density, whereas the length of the costal strip forming the heavy longitudinal costa is constant.