Fine-structure of the vegetative frustule, perizonium and initial valve of Achnanthes yaquinensis (Bacillariophyta)

Kensuke Toyoda, Masahiko Idei, Tamotsu Nagumo, Jiro Tanaka

Research output: Contribution to journalArticlepeer-review

28 Citations (Scopus)


This study clarifies the fine structure of the vegetative and initial valves of Achnanthes yaquinensis and briefly compares them to other Achnanthes species. It also elucidates the structure of the perizonium, based on auxospore development in short-term cultures. The araphid valve has marginal ridges and terminal spines that allow connecting valves to form a chain. The terminal spines develop from the rapheless sternum. The complete cingulum consists of 3-5 split bands with two rows of areolae. These features can be used to discriminate species within the genus. Sexual reproduction is isogamous with two mother cells producing two auxospores, which are enclosed in mucilage. The perizonium develops on one side of an auxospore only, comprising one large central longitudinal band and four closed bands. There are no transverse perizonial bands. The raphid valve of the initial cell forms first, underneath the longitudinal perizonium, followed by the araphid valve, which is not covered by any perizonial bands. The araphid valve of the initial cells lacks a marginal spine, and the rapheless sternum lies more centrally than in the vegetative cell. The relationship of the genus Achnanthes to other monoraphid diatoms is discussed briefly.

Original languageEnglish
Pages (from-to)269-279
Number of pages11
JournalEuropean Journal of Phycology
Issue number3
Publication statusPublished - 2005 Aug
Externally publishedYes


  • Achnanthes sensu stricto
  • Achnanthes yaquinensis
  • Auxospore
  • Auxosporulation
  • Epiphytic diatom fine structure
  • Initial cell
  • Monoraphid diatom

ASJC Scopus subject areas

  • Aquatic Science
  • Plant Science


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