This volume presents the diatom flora of freshwater environments in karstic
wetlands (cenotes, ponds, inundated savannah) from El Edén Ecological Reserve,
Mexico. 151 samples collected from metaphyton, periphyton and phytoplankton
were examined by the authors. The aim of the study was not only to create
the species list of the area, but to answer the question if the species
composition is influenced by the special geographical, environmental and
ecological features of the area.
Accordingly, an ecological characterisation of species - based on
bibliographic information of their distribution, pH preference and salinity
tolerance - is presented in the book.
It is mentioned by the authors, that in case of some species designated as
"cosmopolitan" in the literature (e.g. species described from alpine
lakes and from shallow water bodles at low altitudes as well), there may be
morphological differences between populations living in different circumstances. Sometimes these differences are left hidden in the descriptions which make determination more difficult.
156 taxa occurred in El Edén Ecological Reserve, 29 of them have a tropical
distribution, 76 are registered as alkalophilous species and 64 have an
affinity to calcareous substrata. According to the results of the
presented investigation, latitudinal situation and environmental features
of the Reserve influence significantly the composition of diatom flora,
which has little similarity with other floras for tropical America, such
as those from Brazil, Venezuela or Guyana, where most of the species are
acidophilous. The most abundant species were: Cymbopleura chacii sp. nov.,
Brachysira microcephala (Grunow) Compére, Encyonema mesianum (Cholnoky)
Mann, E. gracile Ehrenberg, E. mexicanum Krammer and Mastogloiai smithii
Thwaites ex W. Smith.
Species and their distributions are described in the part "Descriptions of
the taxa from El Edén Ecological Reserve". Descriptions of the species are
alphabetically organised according to the system of Krammer and Lange-Bertalot,
with some of the modifications proposed by Round et al. for supraspecific
taxa.
As a result of the study, 9 new taxa are described and 3 new combinations
are proposed: Aulacoseira periphytica sp. nov., Caloneis subanicola sp. nov.,
Capartogramma paradisiaca sp. nov., Cymbopleura cachii sp. nov., Encyonema
densistriata sp. nov., Fragilaria dzonoticola sp. nov., Nitzschia yalahau
sp. nov., Pinnularia mayarum sp. nov., Stauroneis amphibia sp. nov.,
Achnantidium chlinados (Hohn et Hellermann) comb. nov., Cymbopleura
hustedtii (Krasske) comb. nov., Placoneis porifera var. oportuna (Hustedt)
comb. nov.
Unfortunately, descriptions of new species are based on LM observations only,
since the authors found it unambiguous that populations in their samples
clearly differ from other similar species. Hence, only LM micrographs of
the new taxa are found on the 26 figure plates that follows the
descriptional part. According to the methodological part of the book,
the authors have had the possibility to use a scanning electron
microscope; therefore it would have been very useful to examine these
species with the SEM as well, in order to have more exact information
about the morphology of new species, and to take SEM micrographs to
illustrate them.
The volume has a logical structure, and it is nicely edited. It is worth reading
for everyone deals with diatom taxonomy or distribution and for other
researchers of the fields as well.
B. Bolla
Acta Botanica Hungarica 51.2009
