From Frustule
| GENUS Kannoa |
Komura (1980)
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Taxonomic Information
Generitype: Kannoa japonica Komura, 1980
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Genus Description:
Frustules solitary, thick-walled, short robust to long elongated, linear with dissimilar apices, usually straight or often wavy folded in the apical plane, having one end inflated and elevated into a clavate head similar to tobacco-pipe, while the other end is produced into a narrow rod-like prolongation; connecting band and septum not present; valves linear, narrow to broad, somewhat wedge-shaped with dissimilar apices, furnished with a large, prominently raised ocellus and another smaller flattened one; valve face finely striate, arranged bilaterally about the apical axis, except for the broader apical field where it seems hyaline; striae punctate; axial area narrow, in the apical axis.
Diagnosis:
Frustules linear with dissimilar apices, where two ocelli are located, cuneate in girdle view; valve face finely striate; striae punctate, bilaterally arranged about a median axial area. |
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- List of Species belonging to the Genus Kannoa
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General Remarks
An elongated outline of the frustule, a pennate arrangement of striae and the lack of any internal structure such as raphe indicate that the genus should be placed within the Family Fragilariaceae Schutt, 1896. Among the septumless genera of the family, only Astrionella Hassall has such a peculiar cuneate form as Kannoa. The Kannoa differs, however, from that genus in possessing a pair of ocelli at the apical ends. Another well known fossils genus, comparable to Kannoa, with cuneate valve shape may be Sceptroneis Ehrenberg (cf. Hustedt, 1931 37, p. 130; Sheshukova-Poretzkaja, 1963, p. 115), from which it differs in structure of the inflated apical field.
Useful References
- Komura, S., 1980. A new genus of cuneate diatom from the Miocene Masuporo Formation of the Tenpoku district, Japan. Professor Saburo Kanno Memorial Volume. Tsukuba, Japan: Tsukuba Univ. Press, 373-378.
