Fottea, Olomouc, 7(1): 33­38, 2007 33
Morphological characterization of three subaerial Calothrix species
(Nostocales, Cyanobacteria)
Bohuslav UHER
Department of Botany, Faculty of Natural Sciences, Comenius University in Bratislava, Révová 39, SK81102
Bratislava, Slovakia
Abstract: This paper characterizes and discusses the concept of species Calothrix braunii, C. capitularis
spec. nova and C. parietina which were identified on subaerial rocky substrates in gorges of the Slovenský
raj National Park in Slovakia. In this paper, we focused on phenotypic characters, i.e. natural and cultural
morphological variability. Their variable and stabile phenotypic markers are discussed.
Key words: cyanobacteria, cyanophytes, subaerial habitats, Calothrix, Slovenský raj National park, Slovakia
Introduction
The genus Calothrix was firstly described by C.
AGARDH (1824). It is a polymorphic genus with
the inner taxonomy which is unclear yet. The
common features are mainly these: hormogonia
give rise to young filaments with terminal
heterocyte at only one end of the trichome;
mature trichome tapers from base, which bears
a terminal heterocyte, to apex; vegetative cells
disc-shaped, isodiametric or cylindrical
(KOMÁREK & ANAGNOSTIDIS 1989).
The purpose of this research was to
examine the morphological variability and
ontogeny of three species within genus
Calothrix C. AGARDH ex GOMONT et
FLAHAULT 1886 and the congruence of the
natural and culture material. Autecology of
species is discussed.
Material and methods
The Slovenský raj National park (HRIC 1982) is
situated between 20°16'15"-20°31'40"E and
48°57'35"- 48°57'30"N (TULIS 1985). On June 23rd
1999, the samples were scraped from the calcareous
rocky walls in the Kyseľ Gorge (scraped from
KAROLÍNY's Waterfall; No. 1) and in the Kláštorská
Gorge (scraped from ANTON STRAKA's Waterfall;
No. 2). Samples were taken from the wet limestone
walls near the waterfalls and they were kept in
plastic bags at low temperature (4°C) before
examination. The morphology of the species was
studied from both natural and cultured material
using LM Zeiss. Isolated strains: UHER 2000/6527,
UHER 2000/5536 and UHER 1999/011 are deposited
in Department of Botany, Faculty of Natural
Sciences, at Comenius University in Bratislava,
Slovakia. The strains were maintained in the media
BG11 (RIPPKA et al. 1979) and BG110 (RIPPKA
1988) at temperature 20 °C, illumination 500 lx,
continuous light. The cultivation was necessary for
detailed taxonomic studies of these subaerial
cyanobacteria. Species identification follow
KOMÁREK & ANAGNOSTIDIS (1989), nomenclature
unified according to BRUMITT & POWELL (1992).
Results and discussion
Calothrix braunii BORNET et FLAHAULT
(Fig. 1)
Thallus brown-green, microscopic or macroscopic,
fascicular, bushy. Filaments rarely
branched, up to 500 m, at the basis bulbously
wide (7.5)9­12.5(15) m, in the middle of filament
4.5­8.5 m wide, parallelly arranged,
creating macroscopic lines on substrate.
Sheaths yellowish, brownish, not-layered. Trichomes
not clearly constricted at the cross
walls, ended by hairs. Cell sizes at the basis are
(4.5)5­7 × 5­12.5 m, in the middle zone of
trichomes 5­7 × 2.5­5 m. Heterocytes hemi­
spherical, basal, 5­7 m in diameter.
This taxon was found at the site No. 1
and its detail ontogeny was studied from the
strain UHER 2000/6527. C. braunii was recorded
from submerged stones, shells (conches)
and plants in Europe and North America
(FRÉMY 1927, GEITLER 1932, COPELAND
1936, KOSTER 1960, STARMACH 1966),
especially from submerged plants of the genus
Carex (WHELDEN 1947); found on the wall of a
house (described as var. nov. concorta) and the
34 UHER: Three Calothrix species
soil (described as var. nova mollis; GARDNER
1927); from moss tufts on rocks associated with
Nostoc microscopicum (CARMICH.) ELENKIN
(NAKANO 1971). It was also recorded from
rock-pools by KANN (1978), from dead
submersed plants by DROUET (1943) and on
rocks in streams by LÓPEZ & PENALTA (2004)
and UHER & KOVÁČIK (2002). Records
published by EL-AYOUTY et al. (1977), WURTZ
(1947, p. 105), THOMPSON (1938) and COM­
PRE (1967, 1974), seem to represent other
species, because of differences in thallus habit,
character of cells, basal trichome parts and
sheaths. These data show that the habitats
typical of C. braunii are surfaces of wet or
submerged rocks and plants in relatively clear
water (especially dead plants or wood).
Calothrix capitularis spec. nova (Fig. 2)
Latin diagnosis:
Thallus macroscopicus, formae linearis,
fascicularis, olivaceo-viridis aut fusco-viridis;
filamentis heteropolaribus, singulis aut 2­3(5)
consociatis, raro ramosis, parte basali
incrassato concrescentibus, 400­800 m
longis, 7.5­25 m crassis, ad apicem versus
attenuatis, in pilum articulatum productis, pilis
50­150 m longis, 2­3 m crassis. Cellulae
infima basi 15­25 m longae, crassae,
diametro 2-3-plo brevoioes, ad septa
constrictae, cellula basali rotundatosubglobosa.
Trichomata aeruginea vel intense
glauco-viridia, in media parte 5,5­7,5 m
crassa, ad septa plus minusve (interdum valde)
constricta. Sporis ad filorum basin solitariis;
heterocytis basalibus (1), rarius intercalaribus,
rotundato-conicis, incoloratis aut flavis.
Vaginae tenues homogeneae hyalinae.
Reproductio per sporas et hormogonia
heteropolaria.
Locus classicus: in Karoliny cataracta
territorii Slovenský Raj dicti, Slovakia.
Habitatio: Inter petras calcareas ad parietes
humidas territorii Slovenský Raj ("Paradisus
Slovacus") dicti.
Typus: UHER 1999/011 (Herbarium SLO,
Bratislava, SVK), Icona typica (Holotypus):
Figura Nostra 3.
Thallus macroscopic, lines forming, fascicular,
olive or brownish green; created by filaments
arranged parallelly or solitary, rarely branched.
Filaments olive-green, blue-green, up to 800
m long, at the basis expressively cudgelshaped
or elliptically widespread, up to 25 m
wide, after abruptly narrowed continuing by
trichome 7.5­9(10) m wide. Filaments ended
by long hyaline hair, up to 150 m long, 2­3
m in diameter. Trichomes heteropolar, at the
basis with hemispherical terminal heterocyte,
7.5­10 m in diameter. Cells at basis narrowelliptic
or narrow-cylindrical creating spore,
often with clear constrictions by cross walls,
(10)12.5­15(17) m in diameter. Cells in the
middle zone of trichome wider than longer or
isodiametric, 5.5­7.5 m in diameter. Initial
stages 6-10­celled, heteropolar, later creating
specific basal wideness and apical hair.
Reproduction by 6-16 celled hormogonia.
This species was found at the sampling
places Nos 1 and 2. Its detail life cycle was
studied from the strain UHER 1999/011. C.
capitularis spec. nova was compared with all
the validly described Calothrix spp. In
particular, stable characteristics were compared
(not changed by cultivation): shape and
localisation of heterocytes, presence/absence of
hair, terminal part of trichomes (spore/akinete
creation), character of sheath (lamellate or nonlamellate).
The autecological characters were
compared too (see Tab. 1). The ontogeny was
not compared because of lack of ontogenetic
observations in literature. Autecologically close
to C. capitularis are the following epilithic
species: C. braunii f. concorta N.L.GARDNER
(GARDNER 1927), C. breviarticulata f.
tatrensis STARMACH (STARMACH 1966), C.
clausa SETCH. et N.L.GARDNER (GEITLER
1932), C. clavata G.S. WEST (WEST 1914), C.
clavatoides S.L.GHOSE (GHOSE 1927), C.
contarenii (ZANARDINI) BORNET et FLAHAULT
(BORNET & FLAHAULT 1886), C. estonica
KUKK (KUKK 1959), C. fonticola BRABEZ
(BRABEZ 1941), C. fusca f. durabilis
STARMACH (STARMACH 1966; alkaline
substrate), C. parietina (NÄGELI) THUR.
(THURET 1875), C. pulvinata (MERT.) C.
AGARDH (AGARDH 1824), C. simplex
N.L.GARDNER (GARDNER 1927), C. violacea
JAAG (JAAG 1938; alkaline substrate). We
observed C. capitularis sp. nov. on limestone
(alkaline substrate). If the stable morphological
characteristics were compared, then the closest
species are: C. braunii f. concorta N.L.GARDNER,
C. clausa SETCH. et N.L.GARDNER, C.
codicola SETCH. et N.L.GARDNER (SETCHEL &
GARDNER 1930) and C. simplex N.L.Gardner.
C. simplex resembles some sterile initial stages
of our new species (cf. GARDNER 1927). But
the typical features of adult habit of
Fottea, Olomouc, 7(1): 33­38, 2007 35
C. capitularis (presence of spores and wide
terminal cells) are missing in description of C.
simplex.
Calothrix parietina (NÄGELI) THUR. (Fig. 3)
Colonies brown, or olive-green, incrusted by
carbonates. Filaments up to 1 mm, at the basis
(7)9­18.5(23) m wide, in the middle zone
(5.5)7­14(16) m wide, often branched.
Trichomes by the cross walls constricted or not
constricted, in hair ended. Cell sizes at the basis
of trichome (4)5­12 × (4)4.5­9(13) m, in the
middle zone 5.5­12.5 × 5.5­7.5(10.5) m. Heterocytes
terminal, sometimes 2-3 together,
with sizes 7.5­12.5 × 7.5­10.5 m.
This taxon was found at the site No. 2
and its detail ontogeny was studied from the
strain UHER 2000/5536. It is the most recorded
species of genus Calothrix in the literature and
its ecological and taxonomic features, which
are in some cases controversial, are often
discussed. It was recorded as a cosmopolitan
species from rocky streams by DROUET (1943),
from limestone streams by DROUET (1939), on
wet rocks and in pools by Copeland (1936) and
by KANN (1978), from wetted limestone by
ERCEGOVIĆ (1925) and by GOLUBIĆ (1967),
moist soil, stones, wood and rocks by KOSTER
(1960) and on rocks by FRÉMY (1929). But
some original drawings and the description
published as C. parietina are totally different in
habit (cf. COMPRE 1970, SCHWABE 1962),
therefore some floristic data could be lapses.
The lack of exact information, such as
determination of substrata, details about the
habit, makes the published data unclear.
Old records show, that the genus
Calothrix comprises about 80 freshwater and
14 marine morphotypes from temperate,
subtropical and tropical regions. Many of these
taxa are difficult to identify, especially in the
initial young stage, which is a regular
consequence of the cultivation of isolated
strains. Even in natural samples, the shape of
the colonies (filaments, heterocytes,
hormogonia, sheaths) is very variable and if the
size of cells does not differ, the decision
between the names of the species offered by
keys and taxonomic literature (original articles)
is sometimes im-possible.
Several morphological features were
analyzed from natural populations, the
comparisons between natural populations and
cultivated strains were made to demonstrate
stabile phenotypic markers.
The obtained data showed that the variability
of studied species is high and that it is
necessary to analyze a whole life cycle for the
exact identification.
Acknowledgements
Financial support for this study was provided by the
Grants for PhD students at the Faculty of Natural
Sciences of Comenius University in Bratislava
(project No. 10/2002). I would like to express my
gratitude to RNDr. Ľubomír Kováčik, CSc. for his
invitation to acces his collection of literature and
many thanks to RNDr. Petr Marvan, CSc. for
revision of Latin diagnosis.
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 Czech Phycological Society (2007)
Received December5, 2006
Accepted February 27, 2007
Fottea, Olomouc, 7(1): 33­38, 2007 37
38 UHER: Three Calothrix species
Figs 1-3. 1 Calothrix braunii: a young filaments, b adult colony; 2 C. capitularis spec. nova: a initial stages, hormogonia,
b young filaments, c adult filaments, d the basal parts with akinetes; 3 C. parietina: a young filaments, b adult colony.
Scale bars 10 m.