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Figure 8.13 Light microscopy of V. brassicaformis. Stationary culture is composed of
green autosporangia in various phases of sporulation, and orange-colored
zoosporangia filled with tiny zoospores (left panel) (scale bar
m). Each sporan-
gium is equipped with a prominent circular operculum (right panel) (scale bar
¼
10
m
m).
The right panel is reprinted from
Oborník et al. (2012)
, Copyright (2012), with permission
from Elsevier 2011.
¼
10
m
with its plastid being equipped with a conspicuous pyrenoid. In addition to
that,
V. brassicaformis
also substantially differs from
C. velia
in the composi-
tion of its pigments (
Oborn´k et al., 2012
; see below). All in all, both
chromerids for which morphological and life cycle data are available differ
substantially and likely represent only the tip of the iceberg where diversity
of this emerging and widespread group of algae is concerned.
3. LIFE CYCLE
Since no signs of sexual reproduction have been found so far,
only vegetative life cycles are considered for both chromerid
algae (
Oborn´k et al., 2011, 2012
), which likely live in a similar environ-
ment, namely, on the surface of corals, or as symbionts inside of them
(
Cumbo et al., 2013; Janou
ˇ
kovec et al., 2012a,b
). However, the frequent
presence of
Vitrella
-like sequences in waters beyond the coral-inhabited ter-
ritory strongly indicates their capacity to live independently of these ancient
metazoans (
Janouˇkovec et al., 2012a,b
). The life cycle of
C. velia
(
Fig. 8.14
A) starts with the division of a vegetative coccoid, which will
divide into two, three, or four daughter cells in one or two sequential binary
divisions. Autosporangia containing more than four cells have never been
observed in the culture. Autospores can be released from all types of
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