1. Julian Simonato1,2, Silvia E. Sala1, John P. Kociolek3, Jordan K. Swenson3, Michael P.
Kociolek
1División Ficología, Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, La Plata,
Argentina.
2 Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina.
3Museum of Natural History and Department of Ecology and Evolutionary Biology, University of
Colorado, Boulder, USA
Diatom biogeography: distribution of the Luticola
species found in Iguazú National Park

2. Diatom species are closely linked to the chemical characteristics of the waters where they live, grow in particular ranges of pH and
salinity, and have specific ranges and tolerances. Due to their richness of species, specificity of the habitat and resistant siliceous
cover, they are considered excellent ecological indicators (Smol & Stoermer 2010).
Until a few years ago, freshwater diatoms were considered mostly cosmopolitan, but recent studies suggest that endemism in the
group is more the rule than the exception (Kociolek & Spaulding 2000; Telford et al. 2006; van de Vijver 2007; Astorga et al. 2012;
Chong et al. 2015). This situation points out the necessity to obtain information about the biogeography of groups and lineages, as
Kociolek et al. (2019) did with the freshwater diatom genus. A decade ago, the diatoms registered in South America were mostly
cosmopolitan, as a consequence of the use of the available references originating in the northern hemisphere (Morales et al.,
2009, 2014). Recent works showed numerous endemic taxa in the region and floristic differences between different areas
(Metzeltin & Lange-Bertalot 1998, 2007; Rumrich et al. 2000; Vouilloud et al. 2010; Montoya-Moreno et al. 2012; among others),
and the existence of defined distribution patterns, although these have not yet been established.
The Argentine diatom flora has not been approached from a biogeographic perspective. Only Maidana et al. (2005) analyzed a
Patagonian-Antarctic transect and found a high percentage of species in common. On the other hand, when comparing data from
different regions of the country (Frenguelli 1923-1924, 1933, 1941, 1942,1953) it is possible to observe floristic differences
between the Parano-Platense region with typically tropical components, and the Andean-Patagonian region) with a higher
proportion of elements from cold temperate regions of the Northern Hemisphere.
The choice of the genus Luticola Mann in Round et al. (1990) as a model for the biogeographic study of diatoms is based on the
fact that it is a monophyletic genus of more than 200 species with great diversity in in South America and Antarctica. Kociolek et
al. (2017) analyzed the genus in Antarctica and observed that approximately 20% of all species of the genus (42) are endemic to
this continent and there is only one cosmopolitan species in this region. In addition, Simonato et al. (2020 in press) found a
relationship between ultrastructural characters and distribution, delimiting 3 groups: 1) with species mostly from the “New World”,
2) with species from Colombia and Brazil, and 3) with species from all across the world.
The aim of this work is to evaluate diversity to of Luticola species in Iguazú National Park (N.P.) and to establish their distribution
patterns.
Introduction
references originating

3. Materials & Methods
Two expeditions were carried out in Iguazú N.P. (Misiones, Argentina), one in December 2017 and the other in May 2019, in which
samples were taken at 16 sites. Luticola species were found in 8 of them.
The periphyton samples were collected by scraping rocks, macrophytes and filamentous algae in different waterbodies (rivers,
streams, waterfalls and wetlands) and in sites affected by the waterfalls spray.
Sampling sites were georeferenced with a Garmin eTrex 20x GPS. Environmental parameters of the water were also measured:
temperature, pH, conductivity and total dissolved solids (TDS) were determinated with a Hanna HI98130 tester.
Samples were treated to remove organic
matter (van der Werff 1955; Prygiel &
Coste 2000). Cleaned material was air
dried onto glass coverslips and prepared
using Naphrax mounting medium for
observation with light microscopy and on
glass stubs and coated with gold for study
with scanning electron microscopy.
For the analysis of the distribution of the
species found, the following works were
consulted: van de Vijver et al. 2002;
Johansen et al. 2004; van de Vijver &
Mataloni 2008; De Marco et al. 2011;
Levkov et al. 2013; Rodrigues Bartozek et
al. 2013; Chattová et al. 2017;
Glushchenko et al. 2017; Straube et al.
2017; Taboada et al. 2017; Da Silva-
Lehmkuhl et al. 2019).
Map showing the sampling sites in Iguazú N.P.

4. We found a total of 18 species
of the genus Luticola in Iguazú
N.P.
We list the species with their
distribution in the table.
The range environmental
parameters of the water was:
pH: 7.1-7.62
Temp: 19.4-26.8 ºC
Cond: 0.03-0.08 mS/cm
TDS: 0.02-0.04 ppt
Results
Species Distribution
Luticola bartolomeii Silva-Lehmkuhl, T. Ludwig, Tremarin & D. Bicudo, 2019 Brazil
Luticola beyensii Van de Vijver, Ledeganck & Lebouvier, 2002 Brazil, Amsterdam and Saint-Paul Islands
Luticola camopiensis Levkov, Metzeltin & Pavlov, 2013 Brazil, French Guaiana
Luticola dapaloides (Frenguelli) Metzeltin & Lange-Bertalot, 1998 Argentina, Brazil
Luticola ectorii Levkov, Metzeltin & Pavlov, 2013 Argentina, Brazil, Indonesia, China
Luticola fuhrmanii Metzeltin & Levkov, 2013 Brazil, Uruguay, Tanzania
Luticola goeppertiana (Bleisch) D.G.Mann, 1990 Cosmopolitan
Luticola hustedtii Levkov, Metzeltin & Pavlov, 2013 Argentina, Brazil, USA, Congo, Tanzania, Indonesia, New Caledonia
Luticola intermedia (Hustedt) Levkov, Metzeltin & Pavlov, 2013 Brazil, El Salvador, Panama, Indonesia, Vietnam, Papua New Guinea
Luticola isabelae Metzeltin & Pavlov, 2013 Argentina, Brazil
Luticola lagerheimii (Cleve) D.G.Mann, 1990 Ecuador, El Salvador, Argentina
Luticola muticoides (Hustedt) D.G.Mann, 1990 Brazil, USA, Congo, India, Indonesia, Laos
Luticola permuticoides Metzeltin & Lange-Bertalot, 2007 Brazil
Luticola pseudocharcotii Levkov, Metzeltin & Pavlov, 2013 Uruguay
Luticola rhombica (S.J.C.Zimmermann) Levkov, Metzeltin & A.Pavlov, 2013 Brazil, Tanzania
aff. Luticola charlatii (Peragallo) Metzeltin & Lange-Bertalot, 2005 Argentina, Bolivia, Chile, USA, Europe, Azores
aff. Luticola cuspidata Levkov, Metzeltin & Pavlov, 2013 Australia
aff. Luticola friedrichii Levkov, Metzeltin & Pavlov, 2013 Brazil, Uruguay
Some Luticola species that we found:
a: Luticola rhombica b: Luticola pseudocharcotii
c: Luticola isabelae d: Luticola goeppertiana
e: Luticola hustedtii f: Luticola intermedia
g: Luticola ectorii h: Luticola fuhrmanii
i: Luticola lagerheimii j: Luticola dapaloides

5. Of the 18 taxa we found in Iguazú N.P., 8 are from the
Neotropical Kingdom (Takhtajan et al. 1986), 6 are mostly
from tropical regions (Neotropical and Paleotropical
Kingdom), 2 are cosmopolitan, and 2 have disjunct
distributions.
We consider that L. hustedtii and L. muticoides have
tropical distributions, but is necessary to highlight that
these species have also been reported from temperate-
cold regions of USA.
Levkov et al. (2013) mention that L. goeppertiana, is
widely distributed, but also remarked that many records
should be reconsidered, especially in the tropical and sub-
tropical zones.
Concerning species with disjunct distributions, we
consider that a deeper analysis is needed since they
could be cryptic species, which are very common among
diatoms (Beszteri et al. 2005; Amato et al. 2007;
Poulíčková et al. 2010; Degerlund et al. 2012; Kermarrec
et al. 2013; Hamsher & Saunders 2014).
Discussion & Conclusions
Neotropical
Tropical
Cosmpolitan
Disjunct
aff. L. friedrichii
L. bartolomeii
L. camopiensis
L. dapaloides
L. isabelae
L. lagerheimii
L. permuticoides
L. pseudocharcotii
L. muticoides
aff. L. charlatii
L. ectorii
L. fuhrmanii
L. intermedia
L. rhombica
L. hustedtii
L. beyensii
aff. L. cuspidata
L. goeppertiana
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