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9: The Genus Cyanidium
Figure 9.1. Nomarski interference contrast photomicrograph of Cyanidium caldar-
ium cells. The larger cells have already divided.
in the dark it loses its chlorophyll and phycocyanin and becomes a light
straw yellow in color. It will be referred to as the 'acid alga' in this
paper."
She also noted that the morphology and manner of cell division differed
from that of other unicellular blue-green algae. Two years later (Allen,
1954) she published further description of this alga, now calling it a blue-
green Chlorella, because its cell cycle is quite similar to that of this
green
alga. Although she did not specifically note the presence of nuclei or
chloroplasts, she reported that the alga was devoid of diaminopimelic acid,
an acid present in the cell walls of blue-green algae and most bacteria.
  Independently of Allen, Hirose (1950) isolated the alga from an acid hot
spring at Noboribetsu in Hokkaido, Japan, and showed that it possessed
chloroplasts. He used the name Cyanidium for the following reason:
"Because both the genus Cyanidium Geitler and Pluto Copeland were
established in the same year (1936) and moreover the exact dates of their
publications were unknown to him, the author could not assure himself
which of the two has the priority. As F. E. Fritsch (1945) in his treatise
. . .
used Cyanidium caldarium as the name of the present alga, the author also
adopted 'Cyanidium' after Fritsch's opinion as the genus name." Hirose
also proposed that Cyanidium be placed as a member of the Chlorophyta,
because of its morphological resemblance to Chlorella. When Allen (1959)
carried out more detailed work on this organism than she had done earlier,
she could readily perceive that her isolate was similar to Hirose's, and
because Hirose had already used the name Cyanidium, she used it also.
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