Communicating editor: M. M. Watanabe.
Heterocapsa circularisquama sp. nov. (Peridiniales, Dinophyceae): A new marine dinoflagellate causing mass mortality of bivalves in Japan
Article first published online: 22 FEB 2006
Volume 43, Issue 3, pages 129–136, September 1995
How to Cite
Horiguchi, T. (1995), Heterocapsa circularisquama sp. nov. (Peridiniales, Dinophyceae): A new marine dinoflagellate causing mass mortality of bivalves in Japan. Phycological Research, 43: 129–136. doi: 10.1111/j.1440-1835.1995.tb00016.x
- Issue published online: 22 FEB 2006
- Article first published online: 22 FEB 2006
- Received 26-November 1994; accepted 6.April 1995
- body scale;
- Heterocapsa circularisquama sp. nov.;
- red tide;
- toxic dinoflagellate
Heterocapsa circularisquama Horiguchi sp. nov. is described from Ago Bay, central Japan. The dinoflagellate produced large-scale red tides in the bays of central and western Japan and caused mass mortality of bivalves, notably the pearl oysters. The cell is small and is composed of a conical epitheca and a hemi-spheroidal hypothecs. The chloroplast is single and is connected to the single pyrenoid. The nucleus is elongated and is located in the left side of the cell. Thecal plate arrangement has been determined as: Po, cp, 5′, 3a, 7″, 6c, 5s, 5″′, 2″″. Heterocapsa circularisquama is morphologically very similar to Heterocapsa illdefina and it is almost impossible to distinguish these two species at light microscopical level. The characteristics which can be used to distinguish these two species are the morphology of body scales and the ultrastructure of the pyrenoid matrix. The body scales of H. circularisquama possess six radiating ridges on the circular basal plate; no such ridges can be observed on the roughly triangular basal plate of the scales of H. illdefina. Furthermore, the scales of the latter species possess substantially shorter spines compared to those of H. circularisquama. The pyrenoid matrix of H. circularisquama is hardly perforated by cytoplasmic tubules, while in H. tlldefina the pyrenoid matrix is always penetrated by many cytoplasmic tubules. Based on the arrangement of thecal plates, morphology of body scales, and ultra-structure of the pyrenoid, I am placing H. circularisquama sp nov. into the genus Heterocapsa.