the taxonomy and diversity of boring blue-green algae
remain relatively unknown.
Bibliography
Golubic, S., Campbell, S. E., Drobne, K., Cameron, B., Balsam,
W. L., Cimerman, F., and Dubois, L., 1984. Microbial endoliths:
a benthic overprint in the sedimentary record, and
a paleobathymetric cross-reference with foraminifera. Journal
of Paleontology, 58, 351–361.
Tribollet, A., 2008. The boring microflora in modern coral reef ecosystems: a review of its roles. In Wisshak, M., and Tapanila, L.,
(eds.), Current Developments in Bioerosion. Berlin: Springer.
Zhang, Y., and Golubic, S., 1987. Endolithic microfossils
(Cyanophyta) from early Proterozoic stromatolites, Hebei,
China. Acta Micropaleont Sinica, 4, 1–12.
Cross-references
Stromatolites
ALGAE, CORALLINE
Mark M. Littler, Diane S. Littler
Smithsonian Institution, Washington, DC, USA
Synonyms
Calcareous Corallinales; Corallines; Coralline algae;
Nullipores; Rhodalgal facies (geological term)
Definition
Coralline algae are heavily calcified red algae of the order
Corallinales (Rhodophyta). The plant body (thallus) is
composed of chains of cells (filaments) that may fuse laterally or also form secondary (lateral) pit connections.
Separate haploid male and female plants produce gametes
in sori (spore clusters) or domed single-pored conceptacles, with spores (haploid tetraspores or diploid bispores)
being formed in sori that are typically modified into either
single-pored or multipored conceptacles.
Introduction
Coralline algae are important carbonate sediment producers and rank among the major reef builders. Corallines
are characterized by a thallus that is stony because of calcareous deposits contained within and between the cell
walls. This extensive calcite crystalline form of CaCO 3
is a major factor determining the geological importance
of the group. High preservation potential has produced
an excellent fossil record. The colors of these algae are
most typically pink or other shade of red, but some species
can be variations of purple, blue, gray-green, or brown.
Beginning with their discovery in 1707 (Sloane), corallines were thought to be animals. However, in 1837
Philippi recognized that coralline algae were plants and
proposed the two generic names Lithophyllum (for flat
forms) and Lithothamnium (for erect branched forms).
However, in an overlooked earlier treatment, Bory de
Saint-Vincent (1832) had recognized Tenarea undulosa
as a crustose calcareous alga, making it the oldest species
name originally applied to the coralline algae in
a botanical context. For many years, coralline algae were
included in the Order Cryptonemiales as the Family
Corallinaceae until 1986 (Silva and Johansen) when they
were elevated to the Order Corallinales.
Systematics
The Corallinales is a monophyletic group comprised of
three Families (Table 1, Sporolithaceae, Corallinaceae,
and Hapalidiaceae). They also comprise two very distinct
morphological groups [i.e., geniculate (articulated, segmented, jointed) species and nongeniculate (nonarticulated, unsegmented, crustose) species]. Though
useful, this traditional separation no longer constitutes
a phylogenetic arrangement (Bailey, 1999).
Life history
Coralline algae are exclusively marine plants and occur
throughout all of the world’s oceans, where they often
cover most of the available hard substrates, being attached
by crustose expanses (cellular adhesion) or root-like holdfasts (haustoria). Many are epiphytic (on other plants) or
epizoic (on animals), and some are even endophytic parasites within other corallines. Despite their ubiquity, the
coralline algae remain poorly understood by coral-reef scientists, and even by specialist algologists/phycologists.
Corallines reproduce by sori, which are specialized volcano-shaped domed conceptacles containing haploid tetraspores, diploid bispores, or either male or female
gametes. Gametes fuse to form the parasitic diploid
carposporophyte stage within the female conceptacles
and the resultant carpospores germinate into diploid
tetrasporophytes. Haploid tetraspores germinate to produce the male and female gametophytes. Some crustose
coralline populations are unusual in that uninucleate
bispores (diploid) are commonly the sole means of reproduction. The plant body (thallus) is composed of strands
of pit-connected cells (filaments) that may fuse laterally
or also form secondary pit connections. Pit connections
and pit plugs are translocational structures characteristic
of red algae (Rhodophyta). These reproductive and vegetative structures provide the critical anatomical characters
used in coralline algal taxonomy, but also create major
obstacles for workers, since complicated decalcification
techniques and microtome sectioning of infrequently present cryptic features are required.
Articulated (geniculate) corallines are upright or pendulous branched bushy plants (Figure 1), with shallower
and warmer distributions than nongeniculate species.
The multiple clumped thalli are flexible due to
noncalcified zones (genicula, joints) separating longer
20
ALGAE, CORALLINE
remain relatively unknown.
Bibliography
Golubic, S., Campbell, S. E., Drobne, K., Cameron, B., Balsam,
W. L., Cimerman, F., and Dubois, L., 1984. Microbial endoliths:
a benthic overprint in the sedimentary record, and
a paleobathymetric cross-reference with foraminifera. Journal
of Paleontology, 58, 351–361.
Tribollet, A., 2008. The boring microflora in modern coral reef ecosystems: a review of its roles. In Wisshak, M., and Tapanila, L.,
(eds.), Current Developments in Bioerosion. Berlin: Springer.
Zhang, Y., and Golubic, S., 1987. Endolithic microfossils
(Cyanophyta) from early Proterozoic stromatolites, Hebei,
China. Acta Micropaleont Sinica, 4, 1–12.
Cross-references
Stromatolites
ALGAE, CORALLINE
Mark M. Littler, Diane S. Littler
Smithsonian Institution, Washington, DC, USA
Synonyms
Calcareous Corallinales; Corallines; Coralline algae;
Nullipores; Rhodalgal facies (geological term)
Definition
Coralline algae are heavily calcified red algae of the order
Corallinales (Rhodophyta). The plant body (thallus) is
composed of chains of cells (filaments) that may fuse laterally or also form secondary (lateral) pit connections.
Separate haploid male and female plants produce gametes
in sori (spore clusters) or domed single-pored conceptacles, with spores (haploid tetraspores or diploid bispores)
being formed in sori that are typically modified into either
single-pored or multipored conceptacles.
Introduction
Coralline algae are important carbonate sediment producers and rank among the major reef builders. Corallines
are characterized by a thallus that is stony because of calcareous deposits contained within and between the cell
walls. This extensive calcite crystalline form of CaCO 3
is a major factor determining the geological importance
of the group. High preservation potential has produced
an excellent fossil record. The colors of these algae are
most typically pink or other shade of red, but some species
can be variations of purple, blue, gray-green, or brown.
Beginning with their discovery in 1707 (Sloane), corallines were thought to be animals. However, in 1837
Philippi recognized that coralline algae were plants and
proposed the two generic names Lithophyllum (for flat
forms) and Lithothamnium (for erect branched forms).
However, in an overlooked earlier treatment, Bory de
Saint-Vincent (1832) had recognized Tenarea undulosa
as a crustose calcareous alga, making it the oldest species
name originally applied to the coralline algae in
a botanical context. For many years, coralline algae were
included in the Order Cryptonemiales as the Family
Corallinaceae until 1986 (Silva and Johansen) when they
were elevated to the Order Corallinales.
Systematics
The Corallinales is a monophyletic group comprised of
three Families (Table 1, Sporolithaceae, Corallinaceae,
and Hapalidiaceae). They also comprise two very distinct
morphological groups [i.e., geniculate (articulated, segmented, jointed) species and nongeniculate (nonarticulated, unsegmented, crustose) species]. Though
useful, this traditional separation no longer constitutes
a phylogenetic arrangement (Bailey, 1999).
Life history
Coralline algae are exclusively marine plants and occur
throughout all of the world’s oceans, where they often
cover most of the available hard substrates, being attached
by crustose expanses (cellular adhesion) or root-like holdfasts (haustoria). Many are epiphytic (on other plants) or
epizoic (on animals), and some are even endophytic parasites within other corallines. Despite their ubiquity, the
coralline algae remain poorly understood by coral-reef scientists, and even by specialist algologists/phycologists.
Corallines reproduce by sori, which are specialized volcano-shaped domed conceptacles containing haploid tetraspores, diploid bispores, or either male or female
gametes. Gametes fuse to form the parasitic diploid
carposporophyte stage within the female conceptacles
and the resultant carpospores germinate into diploid
tetrasporophytes. Haploid tetraspores germinate to produce the male and female gametophytes. Some crustose
coralline populations are unusual in that uninucleate
bispores (diploid) are commonly the sole means of reproduction. The plant body (thallus) is composed of strands
of pit-connected cells (filaments) that may fuse laterally
or also form secondary pit connections. Pit connections
and pit plugs are translocational structures characteristic
of red algae (Rhodophyta). These reproductive and vegetative structures provide the critical anatomical characters
used in coralline algal taxonomy, but also create major
obstacles for workers, since complicated decalcification
techniques and microtome sectioning of infrequently present cryptic features are required.
Articulated (geniculate) corallines are upright or pendulous branched bushy plants (Figure 1), with shallower
and warmer distributions than nongeniculate species.
The multiple clumped thalli are flexible due to
noncalcified zones (genicula, joints) separating longer
20
ALGAE, CORALLINE