Cyanidioschyzon merolae Genome Project

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Cyanidiaceae Memo

This page contains personal memo for Family Cyanidiaceae. No academic description, merely memo.

Taxonomic Position

Plantae or Protista. Some limit the kingdom Plantae to land plants, or green plants and green algae, although others include all three 'primary' algae (green, red, and blue-brown) to the Plantae. There are some argues on the monophyly of these three 'primary' algae. Nozaki et al. proposed a new and enlarged view of the Plantae.
Rhodophyta or Cyanidiophyta. Doweld adopted the phylum Cynidiophyta under the subkingdom Rhodoplantae, because these organisms are highly distinctive from other red algae.
Cyanidiophyceae. The Cyanidiaceae traditionally belongs to the class Bangiophyceae, but the Bangiophyceae are not monophyletic and divided to some classes now.

Family Feature

These organisms are small unicellular red algae. They live in acidic sulphur hot springs and volcanic calderas, whose temperature and pH are upto 56 °C and 0.5, respectively.

These algae are also notable from the viewpoint of photosynthesis in severe condition. They can proliferate even at 100% CO2 (Kurano et al.).

The highly acidic habitats also means that these algae show great tolerance to metals, especially aluminum. One organism of this family, Cyanidium caldarium, can survive in medium containing 200 mM aluminum (Yoshimura et al.).


Family Cyanidiaceae is generally recognized to be composed of three Genera:

Cell forms and proliferation styles distinguish Cyanidioschyzon from the others. Cyanidioschyzon are club-shaped and proliferated by binary fission, while the others are spheric and make endospores. Gardieria are characterized by their ability of heterotrophic reproduction. Discussion below is based on Ciniglia et al. (2004).


There is a single described species, C. caldarium (Tilden) Geitler. And there are some mesophylic species also known as "cave cyanidium", their habitats are nonacidic and nonthermal. One of such mesophylic species is described as C. chilense, however, its systematic position is unknown. Cinglia et al. (2004) shows mesophily is a derived character in the Cyanidiales.


There are 4 described species: G. sulphuraria (Galdieri) Merola, G. daedala Sentsova, G. partita Sentsova, and G. maxima Sentsova. However, G. maxima seems rather related to genus Cyanidioschyzon based on molecular analyses. Ciniglia et al. (2004) recognize clearly separated 2 subclades, one of which is "endolithic", on the remaining 3 species. At the time, "endolithic" clade found only from Italian sites. The other "hydrothermal" clade shows geographical sorting of the lineages, probably indicating that the long-distance dispersal is limited.


There is a single described species, C. merolae De Luca, Taddei & Varano. C. merolae is clearly distinctive from other Cyanidiaceae species, but G. maxima shows enigmatically close relationship to C. merolae.

Species and Strains

There has been some confusion about the nomenclature of these organisms.


  1. Ciniglia C, Yoon HS, Pollio A, Pinto G, Bhattacharya D (2004) Hidden biodiversity of the extremophilic Cyanidiales red algae. Mol. Ecol., 13: 1827-1838.
  2. Nozaki H, Matsuzaki M, Takahara M, Misumi O, Kuroiwa H, Hasegawa M, Shin-i T, Kohara Y, Ogasawara N, Kuroiwa T (2003) The phylogenetic position of red algae revealed by multiple nuclear genes from mitochondria-containing eukaryotes and an alternative hypothesis on the origin of plastids. J. Mol. Evol., 56: 485-497.
  3. Pinto G, Albertano P, Ciniglia C, Cozzolino S, Pollio A, Yoon HS, Bhattacharya D (2003) Comparative approaches to the taxonomy of the genus Galdieria Merola (Cyanidiales, Rhodophyta). Cryptogamie Algol., 24: 13-32.
  4. Kurano N, Ikemoto H, Miyashita H, Hasegawa T, Hata H, Miyachi S (1995) Fixation and utilization of carbon dioxide by microalgal photosynthesis. Energy Convers. Mgmt. 36: 689-692.
  5. Yoshimura E, Nagasaka S, Sato Y, Satake K, Mori S (1999) Extraordinary high aluminium tolerance of the acidophilic thermophilic alga, Cyanidium caldarium. Soil. Sci. Plant. Nutr. ,45: 721-724.
  6. Gross W, Heilmann I, Lenze D, Schnarrenberger C (2001) Biogeography of the Cyanidiaceae (Rhodophyta) based on 18S ribosomal RNA gene sequence data. Eur. J. Phycology, 36: 275-280.