Algae World: diatom sex and life cycles

Geitler's classification

Professor Dr Lothar Geitler (Vienna) studied the life cycles and cytology of many diatoms during a long working life. His 1932 paper 'Der Formwechsel der pennaten Diatomeen' is a classic work on developmental changes, life cycles and sexual reproduction in pennate diatoms. In this work, he not only gave details of his own work, from observations of cultures and natural populations, but also summarized previous reports of auxosporulation. During the next 50 years, he reviewed progress several times and in 1973, he provided a classification of the different patterns of auxosporulation found in pennate diatoms, based on whether auxosporulation is allogamous or automictic or apomictic, how many gametes are produced, whether fertilization is isogamous or behaviourally anisogamous, and particular features of copulation and gamete fusion. This classification is a very useful framework for exploring and summarizing the diversity of sexual reproduction and auxospore development. For example, the auxosporulation of most Cymbella and Gomphonema species can be summarized as 'Type I A 1 a α'.

Below, we give Geitler's (1973) classification in his own words, with the omission of the examples given.

Typus I

Zwei gepaarte Mutterzellen bilden je zwei funktionsfähige Gameten und zwei Zygoten bzw. Auxosporen.

Typus II

Zwei gepaarte Mutterzellen bilden je einen funktionsfähigen Gameten und eine Zygote bzw. Auxospore.

Typus III

Automixis in ungepaarten oder manchmal (schein)gepaarten Mutterzellen.

Typus IV

Aus einer Mutterzelle diploid parthenogenetische Entwicklung einer Auxospore unter Ablauf einer Pseudomeiose...


Geitler, L. (1932). Der Formwechsel der pennaten Diatomeen. Archiv für Protistenkunde 78: 1–226.

Geitler, L. (1973). Auxosporenbildung und Systematik bei pennaten Diatomeen. Österreichische Botanische Zeitschrift 122: 299–321.

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