A new morphotype of Blennothrix (Cyanoprokaryota, Oscillatoriales) from streams of Brazil and Mexico

Abstract

Blennothrix was proposed by Kützing in 1843, but it was suppressed in the taxonomic starting point of the group. However, Hydrocoleum species with discoid cells and with a special type of branching were transferred to Blennothrix, which was then revalidated. Its species occur in tropical and temperate regions of the world and can be found in saltwater, aerophytic environments and freshwater. They are especially well distributed in marine and brackish environments (coastal areas) and more rarely in terrestrial biotopes (sometimes associated to saline soils). During independent studies carried out in Brazil and Mexico, populations of Blennothrix with same morphology were found growing in streaming water under similar environmental conditions. They clearly correspond to the diagnosis of the genera Blennothrix, but differ of all the species described until now. The detailed taxonomic study revealed that the populations represent a new species of the genus, named B. komarekii, which is described and discussed according to the recent tendencies of cyanoprokaryotean taxonomy. The existence of such stable and widespread morphotype assures that the classical method (based on morphology and metrics), improved with ecological characterization, is still a good tool to describe new taxa. Obviously, additional information from molecular and/or cytological studies is highly desirable but, at this moment, it cannot be considered an obligatory way to reach the identity of cyanoprokaryotean taxa.

Full text

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A new morphotype of Blennothrix (Cyanoprokaryota,
Oscillatoriales) from streams of Brazil and Mexico
By LUIS HENRIQUE Z. BRANCO1* and GUSTAVO MONTEJANO2
1UNESP/IBILCE –Departamento de Zoologia e Botânica, S.J. Rio Preto (SP),
Brazil
2UNAM, Facultad de Ciencias, Laboratorio de Ficologia, Coyoacan, Mexico D.F.
With 12 figures and 1 table in the text
Abstract: Blennothrix was proposed by KÜTZING in 1843, but it was suppressed in the tax-
onomic starting point of the group. However, Hydrocoleum species with discoid cells and
with a special type of branching were transferred to Blennothrix, which was then revali-
dated. Its species occur in tropical and temperate regions of the world and can be found in
saltwater, aerophytic environments and freshwater. They are especially well distributed in
marine and brackish environments (coastal areas) and more rarely in terrestrial biotopes
(sometimes associated to saline soils). During independent studies carried out in Brazil
and Mexico, populations of Blennothrix with same morphology were found growing in
streaming water under similar environmental conditions. They clearly correspond to the
diagnosis of the genera Blennothrix, but differ of all the species described until now. The
detailed taxonomic study revealed that the populations represent a new species of the
genus, named B. komarekii, which is described and discussed according to the recent ten-
dencies of cyanoprokaryotean taxonomy. The existence of such stable and widespread
morphotype assures that the classical method (based on morphology and metrics), im-
proved with ecological characterization, is still a good tool to describe new taxa. Obvi-
ously, additional information from molecular and/or cytological studies is highly desirable
but, at this moment, it cannot be considered an obligatory way to reach the identity of
cyanoprokaryotean taxa.
Key words: Blennothrix, new species, Oscillatoriales, Cyanoprokaryota, Cyanobacte-
ria, streams, Brazil, Mexico.
Introduction
The taxonomy of Cyanoprokaryota has been significantly changed during last
decades due to the use of new criteria, mainly ultrastructural and molecular data.
Particularly, oscillatorialean types have been reorganized and many families and
Algological Studies 121 35–42 Stuttgart, October 2006
0342-1120/06/0163-035 $ 2.00
© 2006 E. Schweizerbart’scheVerlagsbuchhandlung, D-70176 Stuttgart
Algological Studies 121 = Arch. Hydrobiol. Suppl. 164
* author for correspondence
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genera have been modified (ANAGNOSTIDIS & KOMÁREK 1988, KOMÁREK &
ANAGNOSTIDIS 2005), including the revalidation of the genus Blennothrix.
Blennothrix was proposed by KÜTZING 1843 (KOMÁREK 1998), but it was sup-
pressed in the taxonomic starting point of the group. In his monograph, GOMONT
(1892) considered Blennothrix vermicularis KÜTZING a special form (var. β) of
Hydrocoleum glutinosum GOMONT because he observed that the “adherent” fila-
ments described by KÜTZING could not be clearly evidenced in dried material.
GEITLER (1932), BOURRELLY (1985) and further classical authors did not mention
the genus.
However, Hydrocoleum was found to be heterogeneous by ANAGNOSTIDIS &
KOMÁREK (1988) because it included forms with discoid cells and a special type
of branching and also forms with nearly isodiametrical cells and multitrichome
filaments, similar to the type species H. homoeotrichum KÜTZING ex GOMONT.
Thus, the authors included the first type of forms in the genus Blennothrix, which
was then revalidated.
As actually recognized (ANAGNOSTIDIS & KOMÁREK 1988), Blennothrix is
characterized by the presence of discoid cells, produced by rapid transversal fis-
sions, obligatory occurrence of sheaths and presence of coleodesmioid false
branching resulting in two or more trichomes in a sheath. Besides morphological
particularities, the authors also took into account differences in absorption spec-
tra and carotenoids composition. Its validity has been supported by latter studies
(KOMÁREK 1998, KOMÁREK & ANAGNOSTIDIS 2005) and it is actually considered
a well defined and well established genus.
Blennothrix exhibits some similarity with Polychlamydum W. et G. S. WEST in
containing discoid cells and in the obligatory presence of sheath, but it is still not
clear if it forms coleodesmioid branches (KOMÁREK & ANAGNOSTIDIS 2005). Fur-
thermore they differ on the sheath morphology (thick, widened, lamellate or ho-
mogeneous, colorless or colored in Polychlamydum) and number of trichomes in
a filament (isolate in Polychlamydum). However, KOMÁREK & ANAGNOSTIDIS
(2005) recommend a reevaluation of the diagnosis of both genera.
Species of the genus occur in tropical and temperate regions of the world and
can be found in saltwater, aerophytic habitats and freshwater. They are especially
well distributed in marine and brackish environments (coastal areas) and more
rarely in terrestrial biotopes (sometimes associated to saline soils). Some species
occur in running or standing freshwaters and the records have been enhanced
during the last years. Blennothrix ganeshii WATANABE & KOMÁREK (1989), for in-
stance, was described based on a population from central Nepal. This species has
been found in similar biotopes around the world (mainly calcareous, unpolluted
and cold running waters). Besides the type locality, B. ganeshii is also recorded in
Thailand (PISANU WANNATHONG, Chiang Mai University, personal communica-
tion), Mexico (MONTEJANO et al. 2004, CARMONA-JIMÉNEZ et al. 2005) and Brazil
(BRANCO & MERLOTTI 2005).
During independent studies carried out in Brazil and Mexico, we have found,
in both countries, populations with same morphology growing in streaming wa-
36 L. H. Z. BRANCO and G. MONTEJANO
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ter, under similar environmental conditions. They clearly correspond with the di-
agnosis of the genera Blennothrix, but differ of all the species described until
now. The detailed taxonomic study revealed that the populations represent a new
species of the genus, named B. komarekii, which is now described and discussed
according to the recent tendencies of cyanoprokaryotean taxonomy.
Material and methods
During different surveys on stream blue-green algal vegetation in Brazil and Mexico, we
found two distinct populations corresponding to Blennothrix. The samples containing the
specimens were collected in streams in Brazil (Atlantic rainforest, Rio de Janeiro State)
and Mexico (Cloudy Forest, Hidalgo State) and were preserved in 4% formaldehyde so-
lution.
In the lab, the samples were firstly examined under stereoscope microscope for de-
tailed characterization of plant masses. Further, specimens were studied under photonic
microscope according to their qualitative and quantitative taxonomic features. Photomi-
crographic records were performed in order to illustrate the main taxonomic characteris-
tics of the taxon.
Specimens are deposited in the herbaria FCME and SJRP (HOLMEGREN et al. 1990,
HOLMGREN & HOLMGREN 1993).
Results
Blennothrix komarekii BRANCO et MONTEJANO species nova
Diagnosis: Thallus ex filis prostratis intertextis constatus; fila 11,2–27 µm diametro,
interdum ramosa (ramificatione coleodesmioidea); vagina lata, firma, hyalina, aliquando
duobus trichomatibus partialiter superpositis, 8,5–10,3 µm diametro, ad septa constrictis,
apicem versus leviter attenuatis; celulae 2,1–4,2(–4,8) µm longae, latiores quam lon-
giores, longitudine 1/4–1/2latitudinis; contentum cellulare viride vel cyano-viride, granu-
latum; cellula apicalis conica apice rotundato vel hemisphaerica, non capitata, sine calyp-
tra; hormogonia per necridia vel fragmentationem cellularem formata.
Habitatio: in aquis fluentibus; locus classicus: cataracta “de Deus”, Municipium
Penedo, Provincia Rio de Janeiro, Brasilia.
Typus (Holotypus): SJRP 28233, collectus a M. VIS CHIASON.
Etymologia: Species ad honorem Prof. JIRˇÍKOMÁREK (Trˇebonˇ, Czech Republic)
nominata.
Blennothrix komarekii BRANCO et MONTEJANO sp. nova (Figs. 01–12)
Plant mass formed by entangled prostrate filaments, light green; filaments
11.2–27.0 µm wide, sometimes branched (coleodesmioid branching type); sheath
relatively thick, hyaline, sometimes with 2 trichomes partially superimposed in-
side; trichomes 8.5–10.3 µm wide, constricted, slightly tapered at the apex; cells
2.1–4.2(–4.8) µm long, 0.25 to 0.47(–0.53) times as long as wide; cell content
light green, granulated; apical cell conical-rounded to hemispherical, not capitate,
without thickened outer membrane; trichome fragmentation by cell separation or
necridia.
Habitat and geographical occurrence: Brazilian population was
found in a unpolluted mountain stream at Penedo Municipality (“de Deus” water-
Blennothrix from streams of Brazil and Mexico 37
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fall, 22º25’07” S, 44º32’56” W, 628 m altitude, Rio de Janeiro State, collected by
M. VIS-CHIASON, Ohio University) under the following environmental condi-
tions: pH 7.6, water temperature 19.0ºC, conductance 10 µS.cm–1, mean current
velocity 125 cm.s–1, rocky substrate.
Mexican population has been collected in a mountain stream near Tlanchinol,
Hidalgo State (19º59’21” N, 98º39’00” W, 1400 m altitude), under the following
environmental conditions: pH 5.5–7.0, water temperature 12–16ºC , conductance
10.4–15.5 µS.cm–1, current velocity 80 cm.s–1, rocky substrate.
Discussion
Specimens of Brazilian and Mexican populations have very short cells, their tri-
chomes are surrounded by firm sheath, with up to 2 trichomes/filament and the
branches develop from hormogones that remain inside the sheath (coleodesmioid
38 L. H. Z. BRANCO and G. MONTEJANO
Figs 01–06. Blennothrix komarekii sp. nova – specimens from Brazilian population
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type). Therefore, both populations largely correspond to the circumscription of
Blennothrix.
The comparison with previously described Blennothrix species (Tab. 1) re-
vealed a very particular set of characteristics that allows to conclude that those
populations consisted in an undescribed species. The main differences compared
to other taxa are filament, trichome and cell dimensions, sheath characteristics
and ecology.
The occurrence of B. komarekii populations in similar ecological conditions
(streaming oligotrophic water, low conductance and temperatures under 20ºC) in
regions so distant as North and South America confirm the concept about the ex-
istence of stable and recognizable morphotypes. Considering that the genetic
identity of some morphotypes has been proved for oscillatorialean taxa (e.g.
GARCIA-PICHEL et al. 1996), it seems to be adequate to describe morphologically
and ecologically stable morphotypes as B. komarekii.
Blennothrix from streams of Brazil and Mexico 39
Figs 07–12. Blennothrix komarekii sp. nova – specimens from Mexican population.
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40 L. H. Z. BRANCO and G. MONTEJANO
Table 1. Comparison among Blennothrix brebissonii (KÜTZING ex Gomont) ANAGNOSTIDIS et KOMÁREK,B. comoides (GOMONT) ANAGNOSTIDIS et
KOMÁREK and B. komarekii sp. nov. 1according to KOMÁREK & ANAGNOSTIDIS (2005); 2according to GOMONT (1892)
B. brebissonii1B. comoides1,2 B. komarekii
Plant mass fasciculate, rarely solitary hemispherical, cespitose entangled prostrate filaments
sparsely pseudobranched tufts green to violet light green to blue green
black-violet, brownish violet or dark green
Filament more or less straight erect 11.2–27 µm wide
one to several trichomes one to few trichomes with up to 2 trichomes
Sheath lamellate and wide in lower part wide, firm relatively thick
firm and narrow in upper part lamellate hyaline
Trichome (7–)8–10(–11) µm wide 14–21 µm wide 8.5–10.3 µm wide
not constricted constricted or not constricted constricted
sharply attenuated to the apex slightly attenuated to the apex slightly attenuated to the apex
Cell 2.4–5 µm long 3–5 µm long 2.1–4.2(–4.8) µm long
2 to 4 times shorter than wide 0.1 to 0.3 times longer than wide 0.25 to 0.47(–0.53) times longer than wide
septa usually granulated septa granulated septa not granulated
content pale blue-green, grayish purple to content blue-green content light green, granulated
brownish violet or yellowish
Apical cell conical, straight or curved hemispherical (?) conical rounded to hemispherical
with calyptra with calyptra without calyptra
Ecology springs and clear streams coastal areas, marine clear streams
epilithic or epiphytic Australia, Bermuda, Guadeloupe, epilithic
temperate zone (Europe) Indonésia, Jamaica, México tropical (Brazil and Mexico)
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Even though some specialists defend the obligatory use of molecular sequenc-
ing in describing new taxa of cyanoprokaryotes, the initial description and identi-
fication according to morphological criteria is still the easiest method to improve
the knowledge of cyanoprokaryotic diversity. This is particularly true for regions
with high diversity and that are poorly known, like Brazil and Mexico, and it
must be regarded as the first step towards a most complete understanding of
species richness and composition.
It is clear that the development of more detailed studies involving cytomor-
phological and molecular criteria is highly recommended and desirable. These
approaches help understanding the complex evolutionary and taxonomic rela-
tionships in cyanoprokaryotes and are useful in evaluating the validity of some
taxa. However, culturing or sequencing cannot be considered an obligatory requi-
site for the description of new forms in cyanoprokaryotes since recognizable and
stable morphotypes, as Blennothrix komarekii for instance, are commonly found
in nature.
Acknowledgments
We would like to thank to Dr. FERNANDO CHIANG CABRERA (UNAM, Mexico), who kindly
translate the diagnosis to Latin, to Dr. MORGAN VIS CHIASON (Ohio University, USA), for
collecting the Brazilian material, and to CNPq and FAPESP, for the support.
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The authors’ addresses:
Dr. LUIS HENRIQUE Z. BRANCO
UNESP/IBILCE
Zoology and Botany Department
R. Cristóvão Colombo, 2265
BR-15054-000 S.J. Rio Preto (SP), Brazil
e-mail:branco@ibilce.unesp.br
Dr. GUSTAVO MONTEJANO ZURITA
UNAM, Facultad de Ciencias,
Laboratorio de Ficología
Circuito Exterior s/n
Ciudad Universitaria,
MEX-04510 Coyoacan, México D.F.
e-mail: gmz@hp.fciencias.unam.mx
42 L. H. Z. BRANCO and G. MONTEJANO
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