Content uploaded by Edward A. D. Mitchell
Author content
All content in this area was uploaded by Edward A. D. Mitchell
Content may be subject to copyright.
Testate amoebae analysis in ecological
and paleoecological studies of wetlands: past,
present and future
Edward A. D. Mitchell · Daniel J. Charman · Barry G. Warner
Abstract Testate amoebae are an abundant and diverse polyphyletic group of shelled
protozoa living in aquatic to moist habitats ranging from estuaries to lakes, rivers, wet-
lands, soils, litter, and moss habitats. Owing to the preservation of shells in sediments,
testate amoebae are useful proxy indicators complementary to long-established indicators
such as pollen and spores or macrofossils. Their primary use to date has been for inferring
past moisture conditions and climate in ombrotrophic peatlands and, to a lesser extent, to
infer pH in peatlands and the trophic or nutrient status of lakes. Recent research on these
organisms suggests other possible uses in paleoecology and ecology such as sea-level
reconstruction in estuarine environments, as indicators of soil or air pollution, and monitor-
ing recovery of peatland. We review the past and present use of testate amoebae, the chal-
lenges in current research, and provide some ideas on future research directions.
Keywords Testate amoebae · Protozoa · Peatland · Sphagnum · Paleoecology ·
Bioindicators · Community ecology · Transfer functions · Peatland management ·
Restoration ecology
E. A. D. Mitchell (&)
Swiss Federal Research Institute WSL, Wetlands Research Group, Station 2, Lausanne CH-1015,
Switzerland
e-mail: edward.mitchell@wsl.ch
E. A. D. Mitchell
EPFL, Laboratoire des Systèmes Écologiques (ECOS), Station 2, Lausanne CH-1015, Switzerland
D. J. Charman
School of Geography, University of Plymouth, Plymouth, Devon PL4 8AA, UK
B. G. Warner
Department of Earth and Environmental Sciences, University of Waterloo, Waterloo,
ON, Canada, N2L 3G1
Published in Biodiversity and Conservation 17, issue 9, 2115-2137, 2008
which should be used for any reference to this work
1
Introduction
Testate amoebae are unicellular protists, which are ubiquitous in environments such as
lakes, rivers, mosses, and soils, but also occur in estuarine environments (Meisterfeld
2002a, b). They are small (mostly 20–200 m––roughly the size of pollen grains), abun-
dant (e.g., 103–104 individuals g¡1 dry weight peat), and diverse (about 2000 species
described so far, and usually between 10 and 30 species in any given sample). Testate
amoebae build a test (shell) either from proteinaceous, calcareous, or siliceous material.
Some of them form agglutinated tests by gluing together organic or mineral particles from
their surrounding environment. These tests cover a relatively broad range of sizes (over one
order of magnitude) and a high diversity of morphologies (Fig. 1), which allows identiWca-
tion to species level. These tests are usually well preserved in peat and lake sediments
(Warner 1990).
Testate amoebae have a long fossil history, with fossils dated from the Cretaceous
(Boeuf and Gilbert 1997; Foissner and Schiller 2001; Patterson and Kumar 2002; Schmidt
et al. 2001; Schönborn et al. 1999), the Carboniferous (Loeblich and Tappan 1964), and
perhaps even Late Neoproterozoic (Porter and Knoll 2000). Despite this long fossil history,
most paleontological studies of testate amoebae focus on the Quaternary and especially on
the Holocene where they are used as paleobioindicators in lakes and peatlands (Charman
2001; Medioli et al. 1990; Tolonen 1986).
Fig. 1 Light- and scanning electron micrographs of some testate amoebae found in peatlands, illustrating the
range of morphological variability; (a) Trigonopyxis arcula, (b) Hyalosphenia subXava, (c) Bullinularia in-
dica, (d) Nebela tincta, (e) Nebela militaris, (f) Assulina muscorum, (g) Assulina seminulum, (h) Arcella arto-
crea, (i) H. elegans, (j) Physochila griseola, (k) H. papilio, (l) Centropyxis aculeata, (m) Archerella Xavum,
(n) Placocista spinosa var. hyalina, (o) DiZugia bacillifera, (p) N. carinata, (q) Amphitrema wrightianum.
Scale bars indicate approximately 50 m except for A. muscorum: 20 m. SEM were conducted at the Uni-
versity of Alaska Anchorage by K. Kishaba, J. Kudenov and E. Mitchell
2
In this review, we cover selected aspects of the phylogeny, taxonomy, biogeography,
biology and ecology of testate amoebae. We then discuss the application of this knowl-
edge to paleoecological research and present some new Welds of research and application.
This review also constitutes a guide to an extensive selection of the literature on testate
amoebae.
Testate amoeba taxonomy and biogeography: facts and open questions
Higher taxonomic levels: phylogeny
Testate amoebae are a polyphyletic assemblage of at least two major, unrelated taxonomic
groups of mostly heterotrophic unicellular eukaryotes (Meisterfeld 2002a, b; Wylezich
et al. 2002). Testate amoebae have been divided based on pseudopod morphology. The
Wrst group has lobose pseudopodia (order Arcellinida). The second group with Wlose pseu-
dopodia is represented mainly by order Euglyphida. Some testate amoebae possessing
anastomosing networks of reticulopodia, and traditionally classiWed in the phylum Gran-
uloreticulosea (Bovee 1985), have recently been placed among testate amoebae with Wlose
pseudopodia (Meisterfeld 2002b). The phylogenetic position of Arcellinida and Euglyph-
ida, among Amoebozoa and Cercozoa, respectively, has been established based on ribo-
somal DNA sequences (Cavalier-Smith and Chao 1997; Meisterfeld 2002a, b; Nikolaev
et al. 2005; Wylezich et al. 2002). However, DNA sequences are available only for a
small number of taxa and therefore the higher-level taxonomy of both orders still rests
entirely on morphological characters. It is urgent to complete the sequence data for all
families and genera, in order to establish a solid phylogeny based on molecular and mor-
phological characters.
Perhaps because of the uncertainty about their phylogeny, many diVerent names have
been used to describe these organisms: thecamoebians, rhizopods, testate amoebae, testa-
ceans, and arcellaceans. Some of these names implicitly suggest a taxonomic aYliation.
For example, the term arcellaceans implies relationships to the order Arcellinida or the
genus Arcella, which is incomplete and unrepresentative of all testate amoebae. Rhizopods
on the other hand are not restricted to testate amoebae and may include naked amoebae.
We suggest that the terms testaceans or testate amoebae should be preferred as they are
unambiguous.
Lower taxonomic levels: genera and species
The taxonomy of testate amoebae at lower taxonomic levels is largely based on shell mor-
phology and is also unresolved (Lee et al. 2000; Patterson 1996). Although uncertainties at
the higher taxonomic levels have little impact on the usefulness of testate amoebae in eco-
logical and paleoecological research, the establishment of solid phylogenetic relationships
is necessary for determining the taxonomic signiWcance of some important morphological
features that are used to identify the species.
Despite the fact that the common species can usually be identiWed with conWdence, there
is an urgent need for taxonomic revision and a synthesis of the existing data. There are no
recent updated complete monographs or even species lists and many of the approximately
2000 described species are probably never securely identiWed by most ecologists for lack of
appropriate identiWcation criteria, the diYculty in accessing the original descriptions, or
simply because no up to date synthesis exists in which the identiWcation characteristics of
3
all species are clearly described. The identiWcation of species is usually based on mono-
graphs, which often date back to decades or even over a century and which, despite the fact
that none of them includes all the described species, are still the most useful resources
(Cash and Wailes 1915; Chardez 1969, 1991; Corbet 1973; DeXandre 1928, 1929, 1936;
Grospietsch 1958, 1964; Harnisch 1958; Ogden 1983; Ogden and Hedley 1980; Penard
1902; Schönborn 1965b). A few more recent studies provided clariWcations on some
selected taxa (Foissner and Korganova 1995, 2000; Lüftenegger et al. 1988; Schönborn
et al. 1983). A valuable guide for paleoecologists was recently published by the Quaternary
Research Association (Charman et al. 2000). However, much remains to be done to make
the identiWcation of testate amoebae more straightforward for ecologists and paleoecolo-
gists, and through this, the comparison among studies more reliable. The amount of work
involved in such a task is huge and will require a signiWcant investment.
Moreover, the intra-speciWc variability of test morphology in most taxa has not yet been
satisfactorily assessed. It is quite likely that many species have been described based on the
extremes of a continuum of morphotypes of the same variable species (Bobrov and Mazei
2004). Recent studies show that (1) abiotic and biotic environmental factors such as food
source, temperature, and insecticides aVect the shell morphology (Chardez 1989; Schönborn
1992a; Wanner 1999; Wanner et al. 1994; Wanner and Meisterfeld 1994), and (2) testate
amoebae are characterized by a high degree of morphological variability both among and
within populations (Bobrov and Mazei 2004), and (3) even under controlled conditions, the
morphological variability of the shell increases with time (Schönborn 1992a). Such variabil-
ity is apparently at least partly genetically determined and allows the species to adapt to the
spatial or temporal heterogeneity of their environment (Bobrov and Mazei 2004).
Phenotypic plasticity may however not necessarily mean that testate amoebae are less
useful as a tool for ecologists and paleoecologists. Indeed if the relationships between
environmental conditions and shell morphology were well understood and could be
reliably predicted, then this information could be used to infer environmental conditions
on the basis not only of community composition but also of shell morphological charac-
teristics. Instead of having discrete categories (species) along a gradient, ecologists and
paleoecologists would have a continuum. Inference (forecasting) models could then be
built from the analysis of such continua, with linear or polynomial regression. We there-
fore call for more detailed morphometric analyses of (1) living taxa under known environ-
mental conditions, and (2) cultures grown under controlled conditions. This approach will
enable a predictive model of morphological characteristics as a function of environmental
conditions to be created. Such a model would have direct applications for paleoenviron-
mental reconstructions.
The fact that testate amoebae have been found to be useful despite these imperfections
suggests that they could become an even better tool for ecologists if the taxonomy was
improved. The present state of testate amoebae taxonomy and the above-mentioned Wnd-
ings call for (1) a conservative approach to the description of new species and (2) a test of
the morphology-based taxonomy using molecular data (e.g., phylogenetic trees derived
from ribosomal RNA sequences) with the long-term goal of revising the taxonomy of
testate amoebae based on the combination of molecular and morphological data. We
suggest a combined approach focusing on the morphology, molecular taxonomy, and
ecology of problematic groups of species such as the genera DiZugia, Centropyxis,
Phryganella, Trinema, and Euglypha or groups of species within otherwise “easy” genera
such as the Nebela tincta species complex.
4
The debate over cosmopolitanism
The question of the cosmopolitanism of microorganisms is of great importance to the glo-
bal use of testate amoebae as bioindicators and paleobioindicators in peatland. There is cur-
rently a lively debate as to whether free-living protists are ubiquitous (Finlay 2002; Finlay
and Clarke 1999; Finlay et al. 2001; Finlay et al. 1999; Finlay and Fenchel 1999) or
whether some, and perhaps indeed most, of them have limited geographical distributions
(Foissner 1997a, 1998, 1999). Testate amoebae represent an interesting paradox as they
provide evidence for both views. Indeed, the available data suggests that they include both
species small enough to be transported passively over long distances and species large
enough for this to be impossible (Wilkinson 1994; Wilkinson 2001). An often-cited exam-
ple of the latter is Apodera (Nebela) vas (Fig. 2), a species that has so far been found
mostly in the Southern Hemisphere, with some Northern Hemosphere records in Hawaii,
Venezuela, and Central America, but no records from Eurasia or North America (DeXandre
1936; Van Oye 1944). Given the large size of this species (130–210 m), its distinct mor-
phological characteristics, and the larger number of studies on testate amoebae of the
Northern Hemisphere as compared to the Southern Hemisphere, it is very unlikely that it
would have been overlooked.
Excessive splitting of taxa may also give the impression of a higher rate of endemism
than actually exists. Given the variability of shell morphology discussed above, we believe
that many of the described species and even more of the subspecies and varieties should not
be used as evidence for limited distribution ranges as many of them were not conWrmed or
observed by anyone else than the person who Wrst described them. On the other hand, the
existing literature on testate amoebae biogeography is mostly based on the observation of
morphotypes. It remains possible that a given morphological species may in fact hide sev-
eral genetically distinct species (i.e. cryptic species) that may diVer with respect to geo-
graphical distributions and/or ecological requirements. In a diVerent context, cryptic
species of both benthic and planktonic foraminifera have recently been discovered, some of
which have cosmopolitan distribution while others have not (Darling et al. 2004; Darling
et al. 2000; Hayward et al. 2004).
In addition to size, there might also be a diVerence in the cosmopolitanism of species
depending on their habitat: wetland species and species living in the soil litter and mosses
are more likely to be transported over long distances than species living deeper in the soil.
Clearly the debate on cosmopolitan distribution versus local endemism is unlikely to be
resolved unless the size range and habitat are speciWed. Even so, the possible existence of
Fig. 2 Apodera vas (Certes), a testate amoeba found in South and Central America and Sub-Sahara Africa
but lacking from North America and Eurasia. This individual is from a Sphagnum moss collected in Tanzania.
SEM conducted at the University of Alaska Anchorage by K. Kishaba, J. Kudenov and E. Mitchell
5
cryptic species calls for caution and further studies of global and local distribution patterns,
ideally with an approach combining morphological, ecological, and molecular methods
such as ribosomal RNA sequencing (Mitchell and Meisterfeld 2005).
Biology
A review of the present knowledge of the biology of testate amoebae is beyond the scope of
this paper. Much remains unknown about their life, for example the relative importance of
asexual and sexual reproduction (Mignot and Raikov 1992), and their physiology. In the
following paragraphs we will focus only on two aspects that are most relevant to the ecolo-
gist: their shell characteristics and their general role in the ecosystem.
Source of material for test construction
Testate amoebae need to Wnd the required material to build their test and this requirement
may be one of the constraints that determine the micro-distribution of species (Meisterfeld
1977; Schönborn 1963). An example of niche separation between two closely related taxa
can be seen in the vertical micro-distribution of Amphitrema wrightianum and A. Xavum.
Both species may both be found in wet and oligotrophic conditions such as pools in the
centre of raised bogs, with A. Xavum usually with its optima in slightly drier conditions
than A. wrightianum. A. Xavum produces a shell that is entirely composed of proteinaceous
material whereas A. wrightianum uses xenosomes (usually minute organic debris) and
cements them together to create a test. This diVerence in shell construction may prevent A.
wrightianum from fully colonizing the uppermost part of Sphagnum mosses (the capitu-
lum) because there may not be enough free organic or mineral material for shell construc-
tion. A further example of this kind is the occurrence of a number of taxa of the genus
DiZugia (e.g., D. bacillifera, D. elegans, D. leydyi) in very wet conditions on oligotrophic
peatlands. The tests of this genus are also xenosomic and it is likely that the silica particles
predominantly used in the tests are more abundant in shallow pools. These constraints may
also explain some of the patterns of species distribution along micro-environmental gradi-
ents, which are usually interpreted as representing responses to variables such as pH or
moisture that are more easily measured than the availability of xenosomes for shell
construction.
Functional role of testate amoebae
Testate amoebae are usually considered to be predators of bacteria and fungi (Hausmann
et al. 2003). As such they play an important role in the cycling of nutrients in soil, although
clearly Xagellates, naked amoebae and/or ciliates are probably more important, at least in
mineral soils (Clarholm 1981, 1985, 2002; Clarhom and Rosswall 1980; Coûteaux and
Pussard 1983; Schönborn 1992b). However, despite the fact that there are few data on the
functional role of testate amoebae in peatlands, the observation that they are by far the
dominant group of protozoa in Sphagnum suggests that in these ecosystems they play a
signiWcant role (Gilbert et al. 1998a; Gilbert et al. b). In support of this idea, peatland
testate amoebae have also been found to use a wide variety of food sources including other
protists, fungi, organic matter and micro-metazoa such as rotifera (Gilbert et al. 2000).
Despite this general knowledge, it is striking that we still do not have a good idea about the
exact trophic role of most soil protozoa, even of the dominant species.
6
Environmental inXuences on testate amoebae include many potential direct and indirect
eVects. Environmental conditions, such as rising atmospheric CO2 concentrations, global
warming, increased nitrogen deposition, drainage, or changes in rainfall patterns may aVect
soil protozoa directly and, perhaps more importantly, also indirectly through their eVect on
the vegetation and prey organisms (Gilbert et al. 1998a, b; Lussenhop et al. 1998; Mitchell
2004; Mitchell et al. 2003; Treonis and Lussenhop 1997).
Ecology and paleoecology
Community structure and responses to ecological gradients
The responses of testate amoebae to the major ecological gradients in peatlands, such as the
fen-bog transition and the humidity gradient, have long been established (Harnisch 1925,
1927; Heal 1961, 1962, 1964; Schönborn 1962). Later work has provided a more quantita-
tive understanding of these relationships and tested them over a larger geographical range.
The earliest ecological classiWcation of peatland testate amoebae is the eight-class wetness
scale of Jung (1936). More recently, multivariate classiWcations of communities (Meister-
feld 1978, 1979; Mitchell et al. 1999; Tolonen et al. 1994) and quantitative relationships
between community structure and speciWc environmental variables have been explored
using univariate and multivariate statistics (Bobrov et al. 1999; Booth 2001; Charman
1997; Charman and Warner 1992, 1997; Lamentowicz and Mitchell 2005; Mitchell et al.
2000b; Mitchell et al. 1999). These studies generally show that testate amoebae respond
primarily to some measure of moisture (usually either the moisture content of the sample or
the water table depth). Seasonal changes in soil moisture content appear to inXuence shifts
in abundance and community composition (Heal 1964; Quinn 2003; Warner et al. 2007).
SigniWcant relationships have also been found with pH and macro-nutrients when a signiW-
cant range of variability has been sampled (Tolonen et al. 1992). However, in general, the
relationship with pH is secondary to that of hydrology (Booth 2001).
It is also important to emphasise that these empirical relationships do not necessarily
reXect the causes of species responses and are not yet based on a thorough physiological
understanding of testate amoebae. Indirect eVects such as materials for test construction
(see above) may be important, but processes related more directly to hydrology can be sug-
gested. For example, higher soil moisture may allow species with larger tests to success-
fully reproduce because of the thicker water Wlms on plant surfaces (e.g. Assulina
seminulum vs A. muscorum; Nebela tincta var. major vs. N. militaris). In addition to size,
shape is important: Thin tests may be better suited to life in the thin water Wlms under drier
conditions (e.g., Xattened Arcella species such as A. arenaria versus rounder ones such as
A. gibbosa). The spines on the surface of some taxa may be an adaptation to limit move-
ment in very wet conditions and where similar spined and glabrous taxa occur, the former
mostly occupies wetter niches (e.g., Euglypha ciliata and E. ciliata var. glabra, Placocista
spinosa and P. spinosa var. hyalina) (Bobrov et al. 1999). Further work on the ecological
and physiological mechanisms underlying the recorded gradients is required to fully under-
stand why testate amoebae communities vary in response to the key variables of hydrology
and water chemistry.
Comparisons among diVerent areas of the world reveal that many taxa have very similar
water table depth optima but that others (e.g., Centropyxis aculeata, Hyalosphenia papilio,
H. elegans, Cyclopyxis arcelloides, Nebela tincta, H. subXava) vary in their relative posi-
tion on the hydrological gradient (Fig. 3). Such comparative results can however be
7
strongly biased by (1) the range of hydrological conditions sampled, (2) the way the water
table was measured (e.g., single point measurement or long-term average), and (3) the tax-
onomic resolution (see above). The only way to truly ascertain that testate amoebae indeed
have similar responses to ecological gradients in diVerent regions is to carry out a multi-site
study with a standard protocol, from sampling strategy to numerical analyses. This has not
been done to date. This question also relates to two other fundamental questions: (1) the
supposed cosmopolitanism of testate amoebae (see above), and (2) the possible response of
testate amoebae to climate (see below). If testate amoebae are not truly cosmopolitan, or if
they respond to temperature in addition to responding to moisture and pH, then it may be
possible that the ecological preferences of a given morphological species is not identical in
diVerent geographical areas. If true this could also mean that the ecological preferences of
species could have change over time, perhaps even within the Holocene.
Within each community or microhabitat type there are more subtle diVerences in faunas
such as changes in the relative abundance of species. For example, the micro-distribution of
testate amoebae along Sphagnum stems suggests that they are highly sensitive to vertical
micro-environmental gradients (e.g., light, moisture) (Bonnet 1958; Booth 2002; Chacharo-
nis 1954, 1956; Heal 1962, 1964; Meisterfeld 1977; Mitchell and Gilbert 2004; Schönborn
1963). Furthermore, even in an apparently homogeneous surface such as an almost Xat,
Fig. 3 Water table depth optima of testate amoebae in Sphagnum peatlands: a summary of studies fro
m
Europe, North America and New Zealand, modiWed from Booth (2001), with kind permission from the Jour-
nal Wetlands
8
monospeciWc Sphagnum lawn, complex patterns of community structure can be observed.
Using geostatistical tools, such patterns may be explained by the heterogeneity of the envi-
ronment such as the micro-topography (e.g. maximum vertical diVerence of 6 cm within a
40 £60 cm area) and associated small diVerences in moisture conditions and water chemis-
try (Mitchell et al. 2000a).
Questions remain surrounding the degree to which seasonal changes and microsite spa-
tial patterns in faunal abundances and composition are controlled by biological inXuences
on the animals themselves or by environmental factors or both. In a recent study, Warner
et al. (2007) collected Sphagnum from various microhabitats an open peatland for seasonal
comparisons of testate amoebae faunas. A moderate shift in testate amoebae community
composition is observed in spring compared to summer and fall faunas (Fig. 4). These
changes may be due to moisture Xuctuations, or to diVerences in seasonal dynamics among
testate amoebae species.
Much of the work to date has focussed on testate amoebae in Sphagnum-dominated
peatlands, primarily in the northern hemisphere. Very little is known about testate amoe-
bae faunas in other types of peatlands, especially in tropical and subtropical latitudes.
For example, testate amoebae have been found in peat cores from herbaceous “popales”
peatlands in tropical central Mexico (Primeau 2004). Similarly, testate amoebae have
been found in the isolated high-altitude “bofedales” Juncaceae-dominated peatlands in
the central Andes of South America (Earle 2000; Warner unpublished). Much remains to
be learned about the ecology and paleoecology of testate amoebae in the lesser-known
Fig. 4 Sample plot of canonical correspondence analysis (CCA) of testate amoebae data in an open peatland
area. The study site is a small “schwingmoor” peatland complex dominated by Sphagnum in southern Ontar-
io, Canada. The site is dominated by Chamaedaphne calyculata and Vaccinium oxycoccus with hummocks
of S. fuscum and S. capillifolium, and lawns of S. magellanicum, and hollows of S. cuspidatum. Samples o
f
Sphagnum were collected for testate amoebae analysis. Species data were log-transformed, and rare species
were down-weighted. Empty circle: spring; Wlled circle: summer; triangle: fall (October). Warner et al.
(2007)
-1.0 1.0Axis 1
.1-0 .10xAsi2
9
peatlands in other geographic regions of the world. Perhaps some light could be shed on
the evolutionary and biogeographic questions discussed above and help assess the
reliability of testate amoebae-derived transfer functions over broad geographical areas
and using that as a substitute for time, the long-term stability of these models.
Transfer functions using testate amoebae in peatland paleoecology
The development of large ecological data sets relating testate amoebae to major ecological
gradients has led to the development of transfer functions used in paleoecology. Transfer
functions describe the relationship between species and an environmental variable of inter-
est (e.g., depth to water table) statistically, and then apply this relationship to fossil assem-
blages to provide estimates of changes in the environmental parameter through time.
Several characteristics make testate amoebae especially useful in paleoecological studies:
(1) the tests of many taxa of testate amoebae are well preserved in a variety of lacustrine
and terrestrial organic sediments, (2) they are abundant and diverse (Warner 1987), (3) they
respond quickly to environmental changes (Buttler et al. 1996), (4) they provide informa-
tion about the exact coring location (as opposed to e.g. pollen and spores), and (5) they may
not respond to exactly the same factors as other indicators such as vascular plants (Mitchell
et al. 2000b) and thus provide an independent line of evidence for multi-proxy paleoeco-
logical reconstructions (Schreve and Thomas 2001). The growing number of paleoecologi-
cal studies that have used testate amoebae now attest to the value of the transfer function
approach to palaeoenvironmental reconstruction (Beyens and Chardez 1987; Charman
2001; Charman et al. 2001; Charman and Hendon 2000; Charman et al. 1999; Charman
et al. 1998; Mitchell et al. 1999; Warner and Charman 1994; Warner and Chmielewski
1992; Woodland et al. 1998). Testate amoebae are also central to an EU-funded research
project (ACCROTELM), which aims to provide data on mid-late Holocene climate
changes by analysing testate amoebae in peat sediments.
The robustness of any transfer function approach depends partly on the availability of
good quality modern data sets but also on an assumption that the species-environment
relationship has been stable through time. It is impossible to verify that the ecology of the
species has remained constant through time, which is one of the basic assumptions of
paleoecology. But it is possible to assess if species-environment relationships are similar
across broad geographical areas. The rationale for this approach is that if testate amoebae
were able to adapt to local conditions relatively rapidly, it would then be possible to detect
diVerences in their ecological optima among study sites. As noted above, when this is done,
the ecological preferences of most species generally compare quite well even between
widely spaced sample regions (Booth 2001; Lamentowicz and Mitchell 2005), and this
provides a good basis for the application of transfer functions over at least recent geological
time periods. But there are also exceptions and these call for further studies.
Another possible limitation of testate amoeba analysis is the lack of modern analogues
to some past communities. One such example has recently been stressed for a community
strongly dominated by Hyalosphenia subXava and DiZugia pulex (Caseldine and Gearey
2005). It remains to be established is such lack of modern analogues are real or if they
perhaps reXect an incomplete sampling for the development of transfer functions. It is
indeed possible that such communities represent very degraded situations that could be
avoided, consciously or not, when collecting surface samples. For example, Hyalosphenia
subXava was found to be associated with forested peatlands in Ontario (Charman and
Warner 1992), while it was characteristic for drained peatlands in Finland (Tolonen et al.
1994). The case of DiZugia pulex is more complex as this species has not been found to
10
dominate any surface sample to this date. Perhaps we should aim speciWcally for unusual
habitats within peatlands to Wnd communities such as the above-mentioned one?
In ombrotrophic peatlands, the moisture content of the Sphagnum mosses and the depth
to the water table are directly linked to climate, and more speciWcally to the balance
between evaporation and precipitation (direct responses to temperature are treated further).
The response of testate amoebae to moisture in these ecosystems therefore makes them
good indicators of paleoclimate and this is how reconstructed water table depths are now
often being interpreted (Charman et al. 2004; Chiverrell 2001; Hendon and Charman 2004;
Hendon et al. 2001; Langdon et al. 2003; Mauquoy and Barber 1999, 2002; McGlone and
Wilmshurst 1999; Wilmshurst et al. 2002). In these cases, modelling the relationship
between testate amoebae and hydrology is only one part of the process. The reconstructions
that can be obtained using this approach have been tested against other hydrological prox-
ies such as plant macrofossils and peat humiWcation (Blundell and Barber 2005; Booth and
Jackson 2003; Booth et al. 2004; Charman et al. 2001; Charman et al. 1999; Lavoie and
Richard 2000; Mauquoy and Barber 2002; McGlone and Wilmshurst 1999; McMullen
et al. 2004; Mitchell et al. 2001; Wilmshurst et al. 2002). Blundell and Barber (2005) con-
cluded that testate amoebae provided more consistently reliable reconstructions that the
other techniques, but that a multi-proxy approach is nevertheless preferable. The accuracy
of reconstructions that can be obtained can also be demonstrated by comparisons with
instrumental records of water table change and climate variability over the relatively recent
past (Charman et al. 2004). This study showed that even the relatively low amplitude
changes in water table that have occurred over the past 50–200 years can be reconstructed
with some conWdence using a transfer function approach. The root mean squared error of
prediction for the transfer function used in this study (Woodland et al. 1998) was only
3.5 cm.
The degree of preservation of subfossil testate amoebae in peat or other sediments can
be quite variable and may depend on both the condition under which the sediment was pro-
duced and its subsequent history. A major gap exists in our understanding of taphonomic
processes associated with transformation of living plant to peat, and hence transformation
of living testate amoebae faunas to dead faunal assemblages. If we consider that Sphagnum
plants and litter generally lose integrity and mass rapidly immediately upon senescence and
early stages of decomposition compared to later stages, and how Sphagnum litter travels
through the oxic layer before entering the deeper anoxic layers, how might such processes
and length of time shape dead testate amoebae communities? Is it possible that dead fossil
assemblages are mixed assemblages that originated from diVerent microhabitats? In order
to provide answers to such questions, more attention should be devoted testate amoeba
taphonomy; it could indeed become a discrete Weld of study in itself.
Future applications of testate amoebae
The short generation time and wide distribution (albeit with reservations in mind regarding
cosmopolitanism) of testate amoebae makes them good indicators for the monitoring of
environmental change. Their usefulness as bioindicators is not restricted to long-term
hydrological development of Sphagnum peatlands. Although a large proportion of the work
on peatland ecology has focused on the reconstruction of former hydrological conditions,
other applications have also been developed. In particular, pH changes can be reconstructed
eVectively (Mitchell et al. 2001). Testate amoebae can also be used to assess the ecological
impact of some speciWc events such as the deposition of volcanic ash on peatlands (Dwyer
11
and Mitchell 1997). A range of new applications has thus been emerging over the past
10 years and others are being reinvigorated by renewed interest. A number of examples are
given here. Such new developments are very promising and may still represent only a frac-
tion of the full potential of testate amoebae in ecological and paleoecological research.
Limnology and palaeolimnology
Studies on the ecology of lake and river testate amoebae have shown that they respond to
the trophic status, pH, and pollution (Beyens et al. 1986; Burbidge and Schröder-Adams
1998; Dalby et al. 2000; Kumar and Patterson 2000; Moraczewski 1962; Ruzicka 1982;
Schönborn 1965a, 1966, 1973; Schönborn et al. 1965). Testate amoebae communities may
also respond to large scale changes in land use such as deforestation and subsequent
watershed management such as fertilizer and pesticide use (Patterson et al. 2002; Scott and
Medioli 1983). It has also been suggested that some taxa respond directly to climate and
mean temperature change (McCarthy et al. 1995). As in peatlands, the preservation of tests
in many lake sediments means that subfossil testate amoebae communities can be used to
trace changes in these environmental conditions over time (Ellison 1995; Ruzicka 1982;
Schönborn 1973). It is important that interpretation of lacustrine assemblages take into
account the diverse range of inXuences on testate amoebae in these environments. For
example changes to more acidic indicators in a lake may reXect soil development in the
catchment and transport of soil dwelling tests in run oV water rather than a change in lake
water conditions (Ellison 1995).
Sea-level change
Testate amoebae have been found in estuarine environments, where their range overlaps
with that of foraminifera, a large group of protists much better known in the marine realm
(Charman et al. 1998; Gehrels et al. 2001; Medioli et al. 1990; Scott et al. 2001). As with
other habitats there are still diverse opinions on the taxonomy of this particular group of
testate amoebae but it is clear that in marginal coastal settings there is a strong zonation of
testate amoebae assemblages. This has been shown in a number of locations in the UK
(Charman et al. 2002), and North America, where the testate data are normally considered
along with foraminifera (e.g., Scott et al. 2001). Earlier studies tended only to examine
larger taxa found in the same size range as foraminifera (>63 m) but more recent studies
have demonstrated that a much greater abundance and diversity of taxa can be found when
a smaller size range is included (Charman et al. 1998).
In a similar approach to that used for peatland water tables (see above), multivariate sta-
tistical methods can also be applied to the sea-level data to provide estimates of individual
taxon optima and their ability to predict mean sea-level elevation (Fig. 5). By comparison
with other bio-indicators of sea level, testate amoebae are particularly abundant and show
strongest zonation in the upper parts of saltmarshes. In these situations, they have the
potential to produce much more precise estimates of sea-level elevation than groups such as
foraminifera and diatoms. Combining groups together may provide an optimum approach
to reconstruction of former sea levels from saltmarsh sediments (Gehrels et al. 2001). Use
can also be made of testate amoebae in understanding the rates of transition from saline
lagoon to freshwater lake environments in isolation basins where sea level has fallen. As
with saltmarsh sediments, extending the range of size fractions analysed yields a much
richer assemblage of tests (Lloyd 2000; Roe et al. 2002).
12
While all the modern studies conWrm that elevation in relation to mean sea level is by far
the most important determinant of assemblage composition in coastal environments, it is
clear that other factors may also play a signiWcant role. Elevation is a proxy for period of
tidal inundation, which creates diVerences in hydrological and salinity conditions across a
saltmarsh. However, salinity may vary independently from elevation (for example in rela-
tion to micromorphology of a saltmarsh) and other factors such as particle size and organic
content of the substrate probably also play a role (Charman et al. 2002).
To date, most of the work on coastal testate amoebae has focused on contemporary ecol-
ogy. The ultimate aim of much of the work is to apply it in palaeo-reconstructions. Initial
assessments of the abundance of fossil tests in a variety of coastal sediments suggests preser-
vation of tests may be quite variable and that capitalising on this potential application will
need careful site selection (Roe et al. 2002). Certainly conditions in coastal settings are more
physically dynamic and geochemically variable than those found in acid peatlands and lakes,
and this probably explains why Wnding well-preserved tests is still a challenging prospect.
Paleoclimatology
Testate amoebae are now being used as indicators of paleoclimate in ombrotrophic peat-
lands only indirectly, through their response to hydrological changes. Their usefulness as a
paleoecological tool would be much greater if one could show that they also respond
directly to temperature changes. Such a response is suggested by patterns of testate amoe-
bae diversity in relation to latitude. Indeed, testate amoeba diversity decreases with increas-
ing latitude: §300 taxa in the Arctic (Beyens and Chardez 1995) from a total of §2000,
and a decline in nebelid (Nebela species and closely related taxa) species richness were
observed towards high southern latitudes (Smith 1992, 1996; Wilkinson 1994). But are
these trends real or are they rather due to lower available and therefore sampled habitat
diversity?
Fig. 5 Optimum position in the tidal frame of testate amoebae in British saltmarshes. The circles show the
optimum and the bars the tolerance of each taxon. Data are plotted as the % of time (square root) that a loca-
tion is Xooded by the tide over an annual cycle. i.e., lower values are higher up the saltmarsh and subject to
less Xooding. See Gehrels et al. (2001) for details. Reproduced with permission of the Quaternary Research
Association
13
F
i
g.
6
Testate amoe
b
a
di
agram
showing the vertical distribution,
as relative proportions, of testate
amoebae in a peat monolith from
Le Cachot, a cutover bog in the
Swiss Jura Mountains. Zone des-
ignations are: L, living Sphagnum
mosses; S, secondary peat; D&O,
detrital and old cutover horizon;
DC, highly decomposed catotelm
peat; CA, catotelm peat. See But-
tler et al. (1996) for details.
Reproduced with permission of
the New Phytologist
14
The main diYculty to address the possible inXuence of temperature on testate amoebae
is to take into account the confounding eVects of factors such as water table, pH, and host
plants. Indeed, plant communities and soil types are generally strongly correlated to latitu-
dinal and altitudinal gradient (Odum 1971). It is not surprising that micro-organisms living
in soil or mosses also respond strongly to this gradient if they are analysed in the diVerent
habitats (soil type or moss species) found along a climatic gradient, as has usually been the
case (Loranger et al. 2001; Todorov 1998).
One way to avoid confounding factors is to limit the study to a very speciWc habitat such
as one moss species. To date the only study in which a standard substrate was used (a single
moss species, Hylocomium splendens, sampled in similar situations along three altitudinal
gradients) has failed to demonstrate a signiWcant overall reduction in diversity with increas-
ing altitude (Mitchell et al. 2004). Such a result suggests that testate amoebae may not
respond very clearly to temperature, at least not in terms of overall diversity. Further stud-
ies are needed, perhaps in diVerent regions or habitats. To properly address this issue
requires (1) a well-deWned sampling protocol to explore the natural patterns, and (2) an
experimental approach to test the eVect of temperature alone on the amoebae.
Peatland regeneration and management monitoring
Much of this review concerns applications of testate amoebae analysis to palaeoenviron-
mental reconstructions and interpretation of past conditions. Some of these cover the recent
past (i.e., less than 300 years) (Buttler et al. 1996; Hendon and Charman 2004; Patterson
et al. 2002; Reinhardt et al. 2001). However, there is a growing recognition that testate
amoebae can also be used in shorter-term biomonitoring. For example, testate amoebae are
starting to be used in the monitoring of peatland regeneration (Davis and Wilkinson 2004;
Jauhiainen 2002; Laggoun-Défarge et al. 2004), and peatland management (McMullen
et al. 2004; Vickery and Charman 2004) (Fig. 6).
In wetlands, the small scale variability of testate amoebae assemblages may make represen-
tative repeat sampling diYcult (Mitchell et al. 2000a) and careful sampling strategies are
needed to reliably identify statistically signiWcant diVerences over time or between manage-
ment treatments. Experiments need to include adequate replication to account for spatial vari-
ability. Vickery and Charman (2004) compared testate amoebae populations in experimental
plots following diVerent forestry harvest and hydrological management on a Scottish raised
bog. The overall health of testate amoebae communities was assessed by the percentage of liv-
ing tests present. Improved conditions were created by leaving some tree remains on the bog
rather than clearing away all remnants of harvested trees, and this probably reXects a mulching
eVect, which keeps the moisture content of surface moss higher than in open conditions.
The response of testate amoebae to soil moisture rather than water table depth suggests
that major vegetation change on the mire surface may aVect palaeohydrological reconstruc-
tions independently of climate change. Such changes are only likely to arise from major
human disturbance or severe Wre, which would generally be visible in the pollen or plant
macrofossil record.
Soil and air pollution monitoring
Given the sensitivity of testate amoebae to water chemistry and other micro-environmental
gradients, it is not very surprising that several studies have illustrated how they respond to
soil pollution (Kandeler et al. 1992; Wanner and Dunger 2001, 2002), and to atmospheric
pollution (Balik 1991; Nguyen-Viet et al. 2004). These studies showed that the diversity
15
and in some cases the density of testate amoebae was lower in polluted situations. As was
observed in lake studies, some species seem to tolerate higher pollution levels than others
and may even be found only in the polluted sites (Nguyen-Viet et al. 2007). The exact
reason why some species are more tolerant than others remains to be determined. Very lit-
tle is known about the exact mechanisms by which water chemistry inXuences testate
amoebae.
This response of testate amoebae to pollution could make them very valuable as integra-
tive monitors of pollution. Indeed one major challenge of pollution monitoring is the spatial
and temporal variability of the pollution. To accurately describe the pollution, and hence to
take appropriate actions to limit its impact on the health of Humans and the environment, it
is necessary to have continuous or very regular measurements. This approach, combined
with the observation of living organisms, constitutes the optimal approach. This may be an
option in developed countries, but is not in many poor regions. In such cases, a biomonitor-
ing approach, either alone or combined with a lower resolution sampling for chemical anal-
yses, could constitute a viable low-cost alternative.
Other possible Welds of study or applications
The reasons that testate amoebae oVer so much potential for biomonitoring applications are
similar to those listed for palaeoenvironmental applications; the speed of response to change is of
the order of days to weeks, and the diversity of the fauna is high. A unique characteristic of tes-
tate amoebae (as compared with ciliates or nematodes for example) is the preservation of the
tests of dead individuals, at least over short periods of time (months to years) in soils. This
means that living and dead assemblages could be used to provide information on very short-term
or long-term conditions respectively. Some comparative studies suggest that testate amoebae
respond more dramatically than ciliates to the conversion of a soil to agriculture, by a reduction
in species richness of up to 50% as compared with neighbouring natural soils (Foissner 1997b).
We believe that we are only seeing a fraction of the potential applications of testate
amoeba analysis as an ecological tool. As examples of some unusual application (albeit far
from the general topic of this review), testate amoebae have been shown to be reliable indi-
cators of the truZe-bearing potential of soils in the South of France (Bonnet 1977, 1979)
and were also used in a murder case: by analysing the testate amoebae found in the mud on
the shoes of a suspect, it could be proven that he had been present at the murder scene
(Lambert and Chardez 1978)!
Concluding remarks
Testate amoebae are clearly an interesting group of bioindicator organisms in peatland
ecology and paleoecology. Like any method, this one currently suVers from some limita-
tions. Some of these are certainly inherent to the organisms themselves but others are due
to current limitations in the knowledge we have on their taxonomy, ecology and biogeogra-
phy. The current interest and research eVort in these organisms will no-doubt increase their
reliability and also extent the range of possible applications in the future.
Acknowledgements Edward Mitchell is supported by Swiss NSF project n° 205321-109709/1 and was
supported by EU project RECIPE, partly funded by the European Commission (n° EVK2-2002-00269) and
partly, for the Swiss partners, by the State Secretariat for Education and Research, Switzerland. SEM illus-
trations were produced at the SEM lab of the University of Alaska Anchorage under the direction of Dr. Jerry
Kudenov. Jan Pawlowski of the University of Geneva provided critical comments on parts of the manuscript.
The critical comments of two anonymous reviewers on the manuscript are gratefully acknowledged.
16
References
Balik V (1991) The eVect of the road traYc pollution on the communities of testate amoebae (Rhizopoda,
Testacea) in Warsaw (Poland). Acta Protozool 30:5–11
Beyens L, Chardez D (1987) Evidence from testate amoebae for changes in some local hydrological condi-
tions between c. 5000 BP and c. 3800 BP on Edgeøya (Svalbard). Polar Res 5:165–169
Beyens L, Chardez D (1995) An annotated list of testate amoebae observed in the Arctic between the longi-
tudes 27 degrees E and 168 degrees W. Arch Protistenkd 146:219–233
Beyens L, Chardez D, Delandt sheer R, Debaere D (1986) Testate amoebae communities from aquatic habitats
in the Arctic. Polar Biol 6:197–205
Blundell A, Barber K (2005) A 2800-year palaeoclimatic record from Tore Hill Moss, Strathspey, Scotland:
the need for a multi-proxy approach to peat-based climate reconstructions. Quatern Sci Rev 24:1261–
1277
Bobrov AA, Charman DJ, Warner BG (1999) Ecology of testate amoebae (Protozoa: Rhizopoda) on peat-
lands in western Russia with special attention to niche separation in closely related taxa. Protist
150:125–136
Bobrov AA, Mazei Y (2004) Morphological variability of testate amoebae (Rhizopoda: Testacealobosea:
TestaceaWlosea) in natural populations. Acta Protozool 43:133–146
Boeuf O, Gilbert D (1997) Presence of testate amoebae (genus:Trinema), in the Upper Pliocene, discovered
in the locality of Chilhac (Haute-Loire, France). Comptes rendus de l’academie des sciences Série II
Fascicule a- Sciences de la Terre et des planetes 325:623–627
Bonnet L (1958) Les thécamoebiens des Bouillouses. Bulletin de la Société d’Histoire Naturelle de Toulouse
93:529–543
Bonnet L (1977) Thécamoebiens et potentialités truYères des sols. In: Communication de la 16ème Réunion
du Groupement des Protistologues de Langue Française, 21 pp
Bonnet L (1979) Thécamoebiens Rhizopoda Testacea et potentialités truYères des sols. Nouvelles données.
Mushroom Sci 10:1013–1038
Booth RK (2001) Ecology of testate amoebae (Protozoa) in two lake superior coastal wetlands: implications
for paleoecology and environmental monitoring. Wetlands 21:564–576
Booth RK (2002) Testate amoebae as paleoindicators of surface-moisture changes on Michigan peatlands:
modern ecology and hydrological calibration. J Paleolimnol 28:329–348
Booth RK, Jackson ST (2003) A high resolution record of late-Holocene mo isture variability from a Michigan
raised bog, USA. The Holocene 13:863–876
Booth RK, Jackson ST, Gray CED (2004) Paleoecology and high-resolution paleohydrology of a kettle peat-
land in upper Michigan. Quatern Res 61:1–13
Bovee EC (1985) Class Lobosea Carpenter, 1861. In: Lee JJ, Hutner SH, Bovee EC (eds) An illustrated guide
to the protozoa. Allen University Press, Lawrence, Kansas, pp 158–211
Burbidge SM, Schröder-Adams CJ (1998) Thecamoebians in Lake Winnipeg: a tool for Holocene paleolim-
nology. J Paleolimnol 19:309–328
Buttler A, Warner BG, Grosvernier P, Matthey Y (1996) Vertical patterns of testate amoebae (Protozoa: Rhi-
zopoda) and peat forming vegetation on cutover bogs in the Jura, Switzerland. New Phytologist
134:371–382
Caseldine C, Gearey B (2005) A multiproxy approach to reconstructing surface wetness changes and prehis-
toric bog bursts in a raised mire system at Derryville Bog, Co. Tipperary, Ireland. The Holocene 15:585
Cash J, Wailes H (1915) The British Freshwater Rhizopoda and Heliozoa Ray Society, London
Cavalier-Smith T, Chao EE (1997) Sarcomonad ribosomal RNA sequences, rhizopod phylogeny, and the ori-
gin of euglyphid amoebae. Arch Protistenkd 147:227–236
Chacharonis P (1954) Observ ations on the ecology of protozoa associated wi th Sphagnum. Dissertation, Ohio
State University
Chacharonis P (1956) Observations on the ecology of protozoa associated with Sphagnum. J Protozool 3:11
Chardez D (1969) Le genre Phryganella Penard (Protozoa, Rhizopoda, Testacea). Bulletin de la Station de
Recherche Agronomique de Gembloux 4:315–322
Chardez D (1989) On the multiplication of Centropyxis discoides and the medium inXuence on the morphol-
ogy of the test (Rhizopoda Testacea). Acta Protozool 28:31–34
Chardez D (1991) The Genus Cyphoderia Schlumberger, 1845 (Protozoa, Rhizopoda, Testacea). Acta Proto-
zool 30:49–53
Charman DJ (1997) Modelling hydrological relationships of testate amoebae (Protozoa: Rhizopoda) on New
Zealand peatlands. J Royal Soc NZ 27:465–483
Charman DJ (2001) Biostratigraphic and palaeoenvironmental applications of testate amoebae. Quatern Sci
Rev 20:1753–1764
17
Charman DJ, Brown AD, Hendon D, Karofeld E (2004) Testing the relationship between Holocene peatland
palaeoclimate reconstruc tions and instrumental data at two European site s. Quatern Sci Rev 23 :137–143
Charman DJ, Caseldine C, Baker A, Gearey B, Hatton J, Proctor C (2001) Paleohydrological records from
peat proWles and speleothems in Sutherland, northwest Scotland. Quatern Res 55:223–234
Charman DJ, Hendon D (2000) Long-term changes in soil water tables over the past 4500 years: relationships
with climate and North Atlantic atmospheric circulation and sea surface temperature. Clim Change
47:45–59
Charman DJ, Hendon D, Packman S (1999) Multiproxy surface wetness records from replicate cores on an
ombrotrophic mire: implications for Holocene palaeoclimate records. J Quatern Sci 14:451–463
Charman DJ, Hendon D, Woodland WA (2000) The identiWcation of testate amoebae (Protozoa: Rhizopoda)
in peats Quaternary Research Association, London
Charman DJ, Roe HM, Gehrels WR (1998) The use of testate amoebae in studies of sea-level change: a case
study from the Taf Estuary, south Wales, UK. The Holocene 8:209–218
Charman DJ, Roe HM, Gehrels WR (2002) Modern distribution of saltmarsh testate amoebae: regional vari-
ability of zonation and response to environmental variables. J Quatern Sci 17:387–409
Charman DJ, Warner BG (1992) Relationship between testate amoebae (Protozoa, Rhizopoda) and microen-
vironmental parameters on a forested peatland in Northeastern Ontario. Can J Zool-Revue Canadienne
De Zoologie 70:2474–2482
Charman DJ, Warner BG (1997) The ecology of testate amoebae (Protozoa: Rhizopoda) in oceanic peatlands
in Newfoundland, Canada: modelling hydrological relationships for palaeoenvironmental reconstruc-
tion. Ecoscience 4:555–562
Chiverrell RC (2001) A proxy record of late Holocene climate change from May Moss, northeast England. J
Quatern Sci 16:9–29
Clarholm M (1981) Protozoan grazing of bacteria in soil - Impact and importance. Microb Ecol 7:343–350
Clarholm M (1985) Interactions of bacteria, protozoa and plants leading to mineralization of soil nitrogen.
Soil Biol Biochem 17:181–187
Clarholm M (2002) Bacteria and protozoa as integral components of the forest ecosystem - their role in cre-
ating a naturally varied fertility. Antonie van Leeuwenhoek J Microbiol 81:309–318
Clarhom M, Rosswall T (1980) Biomass and turnover of bacteria in a peat forest soil and a peat. Soil Biol
Biochem 12:49–57
Corbet SA (1973) An illustrated introduction to the testate rhizopods in Sphagnum, with special reference to
the area around Malham Tarn, Yorkshire. Field Studies 3:801–838
Coûteaux M-M, Pussard M (198 3) Nature du régime alimentaire des protozoaires du so l. In: LeBrun P, André
HM, De Medts A, G régoire-Wibo C, Wauthy G (eds) new trend s in soil biology, proceedings of the VII I.
International colloquium of soil biology, Louvain-la-Neuve (Belgium). pp 179–195
Dalby AP, Kumar A, Moore JM, Patterson RT (2000) Preliminary survey of arcellaceans (thecamoebians) as
limnological indicators in tropical Lake Sentani, Irian Jaya, Indonesia. J Foraminiferal Res 30:135–142
Darling KF, Kucera M, Pudsey CJ, Wade CM (2004) Molecular evidence links cryptic diversiWcation in polar
planktonic protists to Quaternary climate dynamics. Proc Nat Acad Sci USA 101:7657–7662
Darling KF, Wade CM, Stewart IA, Kroon D, Dingle R, Brown AJL (2000) Molecular evidence for genetic
mixing of Arctic and Antarctic subpolar populations of planktonic foraminfers. Nature 405:43–47
Davis SR, Wilkinson DM (2004) The conservation management value of testate amoebae as ‘restoration’
indicators: speculations based on two damaged raised mires in northwest England. The Holocene
14:135–143
DeXandre G (1928) Le genre Arcella Ehrenberg. Morphologie-Biologie. Essai ph ylogénétique et systématiqe.
Arch Protistenkd 64:152–287
DeXandre G (1929) Le genre Centropyxis Stein. Arch Protistenkd 67:322–375
DeXandre G (1936) Etude monographique sur le genre Nebela Leidy. Ann Protistol 5:201–286
Dwyer RB, Mitchell FJG (1997) Investigation of the environmental impact of remote volcanic activity on
North Mayo, Ireland, during the mid-Holocene. The Holocene 7:113–118
Earle LR (2000) The development of an unusual peat-accumulating bofedal ecosystem in the Chilean Alti-
plano. M.Sc. thesis, University of Waterloo
Ellison RL (1995) Paleolimnological analysis of ullswater using testate amebas. J Paleolimnol 13:51–63
Finlay BJ (2002) Global dispersal of free-living microbial eukaryote species. Science 296:1061–1063
Finlay BJ, Clarke KJ (1999) Ubiquitous dispersal of microbial species. Nature 400:828
Finlay BJ, Esteban GF, Clarke KJ, Olmo JL (2001) Biodiversity of terrestrial protozoa appears homogeneous
across local and global spatial scales. Protist 152:355–366
Finlay BJ, Esteban GF, Olmo JL, Tyler PA (1999) Global distribution of free-living microbial species. Eco-
graphy 22:138–144
18
Finlay BJ, Fenchel T (1999) Global Diversity and body size. Answer to Siemann, Tilmann and Haarstad
1999. Nature 383:132–133
Foissner W (1997a) Global soil ciliate (Protozoa, Ciliophora) diversity: A probability-based approach using
large sample collections from Africa, Australia and Antartica. Biodivers Conserv 6:1627–1638
Foissner W (1997b) Protozoa as bioindicators in agroecosystems, with emphasis on farming practices, bio-
cides, and biodiversity. Agric Ecosyst Environ 62:93–103
Foissner W (1998) An updated compilation of world soil ciliates (Protozoa, Ciliophora), with ecological
notes, new records, and descriptions of new species. Eur J Protistol 34:195–235
Foissner W (1999) Protist diversity: estimates of the near-imponderable. Protist 150:363–368
Foissner W, Korganova GA (1995) Redescription of 3 testate amebas (Protozoa, Rhizopoda) from a cauca-
sian soil–centropyxis plagiostoma Bonnet and Thomas, cyclopyxis kahli (DeXandre) and cyclopyxis in-
termedia kuVerath. Arch Protistenkd 146:13–28
Foissner W, Korga nova GA (2000) The Centropyxis aerophila complex (Protozoa: Testacea). Acta Protozool
39:257–273
Foissner W, Schiller W (2001) Stable for 15 million years: scanning electron microscope investigation of
Miocene euglyphid thecamoebians from Germany, with description of the new genus Scutiglypha. Eur
J Protistol 37:167–180
Gehrels WR, Roe HM, Charman DJ (2001) Foraminifera, testate amoebae and diatoms as sea-level indicators
in UK saltmarshes: a quantitative multiproxy approach. J Quatern Sci 16:201–220
Gilbert D, Amblard C, Bourdier G, Francez A-J (1998a) The microbial loop at the surface of a peatland: struc-
ture, function, and impact of nutrient input. Microb Ecol 35:83–93
Gilbert D, Amblard C, Bourdier G, Francez A-J, Mitchell EAD (2000) Le régime alimentaire des thécamoeb-
iens. Annee Biol 39:57–68
Gilbert D, Amblard C, Bourdier G, Francez AJ (1998b) Short-term eVect of nitrogen enrichment on the
microbial communities of a peatland. Hydrobiologia 374:111–119
Grospietsch T (1958) Wechseltierchen (Rhizopoden) Kosmos Verlag, Stuttgart
Grospietsch T (1964) Monographische Studie der Gattung Hyalosphenia Stein. Hydrobiologia 26:211–241
Harnisch O (1925) Studien zur Ökologie und Tiergeographie der Moore. Zoologisch Jahrbuch (Abteilung
Systematik) 51:1–166
Harnisch O (1927) Einige Daten zur recenten und fossilen testaceen Rhizopodenfauna der Sphagnen. Arch
Hydrobiol 18:345–360
Harnisch O (1958) II. Klasse: Wurzelfüssler, Rhizopoda. In: Brohmer P, Ehrmann P, Ulmer G (eds) Die Tierwelt
Mitteleuropas, Band 1: Urtiere-Hohltiere-Würmer, Lieferung 1b. Quelle & Meier, Leipzig, pp 1–75
Hausmann K, Hülsmann N, Radek R (2003) Protistology, 3rd completely revised edition edn. E. Schweizer-
bart’sche Verlagsbuuchhandlung, Berlin, Stuttgart
Hayward BW, Holzmann M, Grenfell HR, Pawlowski J, Triggs CM (2004) Morphological distinction of
molecular types in Ammonia–towards a taxonomic revision of the world’s most commonly misidenti-
Wed foraminifera. Mar Micropaleontol 50:237–271
Heal OW (1961) The distribution of testate amoebae (Rhizopoda: Testacea) in some fens and mires in north-
ern England. Zool J Linn Soc 44:369–382
Heal OW (1962) The abundance and microdistribution of testate amoebae (Protozoa: Rhizopoda) in Sphag-
num. Oikos 13:35–47
Heal OW (1964) Observations on the seasonal and spatial distribution of testaceans (Protozoa: Rhizopoda)
in Sphagnum. J Anim Ecol 33:395–412
Hendon D, Charman DJ (2004) High-resolution peatland water-table changes for the past 200 years: the inXu-
ence of climate and implications for management. The Holocene 14:125–134
Hendon D, Charman DJ, Kent M (2001) Palaeohydrological records derived from testate amoebae analysis
from peatlands in northern England: within-site variability, between-site comparability and palaeocli-
matic implications. The Holocene 11:127–148
Jauhiainen S (2002) Testacean amoebae in diVerent types of mire following drainage and subsequent resto-
ration. Eur J Protistol 38:59–72
Jung W (1936) Thekamöben ursprünglischer lebender deutscher Hochmoore. Abhandlung Landesmuseum
der Provinz Westfalen 7:1–87
Kandeler E, Luftenegger G, Schwarz S (1992) Soil microbial processes and testacea (Protozoa) as indicators
of heavy-metal pollution. Zeitschrift Fur PXanzenernahrung Und Bodenkunde 155:319–322
Kumar A, Patterson RT (2000) Arcellaceans (thecamoebians): new tools for monitoring long- and short-term
changes in lake bottom acidity. Environ Geol 39:689–697
Laggoun-Défarge F, Mitchell EAD, Gilbert D, Warner BG, Comont L, Disnar J-R, Buttler A (2004)
Biochemical characteristics of peat organic matter and distribution of testate amoebae in two naturally
19
regenerating cutover Sphagnum peatlands of the Jura mountains. In: Proceedings of the 12th Interna-
tional Peat Congress, Vol. 1, pp 383–384, Tampere, Finland
Lambert J, Chardez D (1978) Intérêt criminalistique de la microfaune terrestre. Revue Internationale de
Police criminelle 319:158–170
Lamentowicz M, Mitchell EAD (2005) The ecology of testate amoebae (Protists) in Sphagnum in north-west
Poland in relation to peatland ecology. Microb Ecol 39:290–300
Langdon PG, Barber KE, Hughes PDM (2003) A 7500-year peat-based palaeoclimatic reconstruction and
evidence for an 1100-year cyclicity in bog surface wetness from Temple Hill Moss, Pentland Hills,
southeast Scotland. Quatern Sci Rev 22:259–274
Lavoie M, Richard PJH (2000) The role of climate on the developmental histo ry of Frontenac Peatland, south-
ern Quebec. Can J Bot-Revue Canadienne de Botanique 78:668–684
Lee JJ, Leedale GF, Bradbury P (eds) (2000) An illustrated gu ide to the Protozoa, 2nd edn. Lawrence, Kansas,
pp 1432
Lloyd J (2000) Combined foraminiferal and thecamoebian environmental reconstruction from an isolation
basin in NW Scotland: Implications for sea-level studies. J Foraminiferal Res 30:294–305
Loeblich AR, Tappan H (1964) Sarcodina. ChieXy “thecamoebians” and foraminiferida. In: Moore RC (ed)
Treatise on invertebrate paleontology C(2), vol. 1. Geological Society of America and University of
Kansas Press, Lawrence, Kansas, pp C2–C54
Loranger G, Bandyopadhyaya I, Razaka B, Ponge JF (2001) Does soil acidity explain altitudinal sequences
in collembolan communities? Soil Biol Biochem 33:381–393
Lussenhop J, Treonis A, Curtis PS, Teeri JA, Vogel CS (1998) Response of soil biota to elevated atmospheric
CO2 in poplar model systems. Oecologia 113:247–251
Lüftenegger G, Petz W, Berger H, Foissner W, Adam H (1988) Morphologic and biometric characterization
of 24 soil Testate Amebas (Protozoa, Rhizopoda). Arch Protistenkd 136:153–189
Mauquoy D, Barber K (1999) Evidence for climatic deteriorations associated with the decline of Sphagnum
imbricatum Hornsch ex Russ. in six ombrotrophic mires from northern England and the Scottish
Borders. The Holocene 9:423–437
Mauquoy D, Barber K (2002) Testing the sensitivity of the palaeoclimatic signal from ombrotrophic peat
bogs in northern England and the Scottish Borders. Rev Palaeobot Palynol 119:219–240
McCarthy FMG, Collins ES, McAndrews JH, Kerr HA, Scott DB, Medioli FS (1995) A comparison of post-
glacial Arcellacean (Thecamoebian) and pollen succession in Atlantic Canada, illustrating the potential
of Arcellaceans for paleoclimatic reconstruction. J Paleontol 69:980–993
McGlone MS, Wilmshurst JM (1999) A Holocene record of climate, vegetation change and peat bog devel-
opment, east Otago, South Island, New Zealand. J Quatern Sci 14:239–254
McMullen JA, Barber KE, Johnson B (2004) A paleoecological perspective of vegetation succession on
raised bog microforms. Ecol Monograp 74:45–77
Medioli FS, Scott DB, Collins ES, McCarthy FMG (1990) Fossil thecamoebians: present status and prospects
for the future. In: Hemleben C, Kaminski MA, Kuhnt W, Scott DB (eds) Proceedings of the NATO
advanced study institute on paleoecology, biostratigraphy, paleoceanography and taxonomy of aggluti-
nated foraminifera, vol. 327, D. Reidel Publishing Company, Dordrecht-Boston, International, pp 813–839
Meisterfeld R (1977) Die horizontale und vertikale Verteilung der Testaceen (Rhizopoda: Testacea) in
Sphagnum. Arch Hydrobiolo 79:319–356
Meisterfeld R (1978) Die Struktur von Testaceenzönosen (Rhizopoda, Testacea) in Sphagnum unter beson-
derer Berücksichtigung ihrer Diversität. Verhandlungen der Gesellschaft für Ökologie 7:441–450
Meisterfeld R (1979) Cluster-Analysis of Associations of Testate Ameba (Rhizopoda, Testacea) in Sphag-
num. Arch Protistenkd 121:270–307
Meisterfeld R (2002a) Order Arcellinida Kent, 1880. In: Lee JJ, Leedale GF, Bradbury P (eds) The illustrated
guide to the protozoa, vol. 2, Society of protozoologists, Lawrence, Kansas, USA, pp 827–860
Meisterfeld R (2002b) Testate amoebae with Wlopodia. In: Lee JJ, Leedale GF, Bradbury P (eds) The illus-
trated guide to the protozoa, vol. 2. Society of protozoologists, Lawrence, Kansas, USA, pp 1054–1084
Mignot JP, Raikov IB (1992) Evidence for meiosis in the Testate Ameba Arcella. J Protozool 39:287–289
Mitchell EAD (2004) Response of testate amoebae (Protozoa) to N and P fertilization in an Arctic wet sedge
tundra. Arct Antarct Alp Res 36:77–82
Mitchell EAD, Borcard D, Buttler AJ, Grosvernier P, Gilbert D, Gobat JM (2000a) Horizontal distribution
patterns of testate amoebae (Protozoa) in a Sphagnum magellanicum carpet. Microb Ecol 39:290–300
Mitchell EAD, Bragazza L, Gerdol R (2004) Testate Amoebae (Protista) Communities In Hylocomium splen-
dens (Hedw.) B.S.G. (Bryophyta): relationships with altitude, and moss elemental chemistry. Protist
155:423–436
20
Mitchell EAD, Buttler A, Grosvernier P, Rydin H, Albinsson C, Greenup AL, Heijmans MMPD, Hoosbeek
MR, Saarinen T (2000b) Relationships among testate amoebae (Protozoa), vegetation and water chem-
istry in Wve Sphagnum-dominated peatlands in Europe. New Phytologist 145:95–106
Mitchell EAD, Buttler AJ, Warner BG, Gobat JM (1999) Ecology of testate amoebae (Protozoa: Rhizopoda)
in Sphagnum peatlands in the Jura mountains, Switzerland and France. Ecoscience 6:565–576
Mitchell EAD, Gilbert D (2004) Vertical micro-distribution and response to nitrogen deposition of Testate
amoebae in Sphagnum. J Eukaryot Microbiol 51:485–495
Mitchell EAD, Gilbert D, Buttler A, Grosvernier P, Amblard C, Gobat J-M (2003) Structure of microbial
communities in Sphagnum peatlands and eVect of atmospheric carbon dioxide enrichment. Microb Ecol
46:187–199
Mitchell EAD, Meisterfeld R (2005) Taxonomic confusion blurs the debate on cosmopolitanism versus local
endemism of free-living protists. Protist 156:263–267
Mitchell EAD, van der Knaap WO, van Leeuwen JFN, Buttler A, Warner BG, Gobat JM (2001) The palaeo-
ecological history of the Praz-Rodet bog (Swiss Jura) based on pollen, plant macrofossils and testate
amoebae (Protozoa). The Holocene 11:65–80
Moraczewski J (1962) DiVerenciation ecologique de la faune des Testacés du littoral peu profond du lac
Mamry. Pol Arch Hydrobiol 10:334–353
Nguyen-Viet H, Bernard N, Mitchell EAD, Cortet J, Badot P-M, Gilbert D (2007) Relationship between
testate amoebae and atmospheric heavy metals (Pb, Cd, Zn, Ni, Cu, Mn and Fe) accumulated in the moss
Barbula indica Hanoi, Vietnam. Microb Ecol 53:53–65
Nguyen-Viet H, Gilbert D, Bernard N, Mitchell EAD, Badot P-M (2004) Relationship between atmospheric
pollution characterized by NO2 concentrations and testate amoebae abundance and diversity. Acta Protozool
43:233–239
Nikolaev SI, Mitchell EAD, Petrov NB, Berney C, Fahrni J, Pawlowski J (2005) The testate lobose amoebae
(order Arcellinida Kent, 1880) Wnally Wnd their home within Amoebozoa. Protist 156:191–202
Odum EP (1971) Fundamentals of ecology, 3rd edn. W. B. Saunders Co., Philadelphia
Ogden CG (1983) Observations on the systematics of the genus DiZugia in Britain (Rhizopoda, Protozoa).
Bull Nat Hist Mus Zool 44:1–73
Ogden CG, Hedley RH (1980) An atlas to freshwater testate amoebae. Oxford University Press, Oxford
Patterson DJ (1996) Free-living freshwater Protozoa: a colour guide. Manson Publishing Ltd., London
Patterson RT, Dalby A, Kumar A, Henderson LA, Boudreau REA (2002) Arcellaceans (thecamoebians) as
indicators of land-use change: Settlement history of the Swan Lake area, Ontario as a case study. J
Paleolimnol 28:297–316
Patterson RT, Kumar A (2002) A review of current testate rhizopod (thecamoebian) research in Canada.
Palaeogeograp Palaeoclimatol Palaeoecol 180:225–251
Penard E (1902) Les Rhizopodes du bassin du Léman Kündig, Genève
Porter SM, Knoll AH (2000) Testate amoebae in the Neoproterozoic Era: Evidence from vase- shaped micro-
fossils in the Chuar Group, Grand Canyon. Paleobiology 26:360–385
Primeau S (2004) Coastal freshwater wetland development in Mexico: A 4,500 -year record of succession
from Laguna La Mancha, Vera Cruz. M.Sc. Thesis, University of Waterloo
Quinn NP (2003) Testate amoebae (Protozoa) assemblages as environmental indicators of water tables and
soil moisture in a kettle hole peatland in southern Ontario. M.Sc. Thesis, University of Waterloo
Reinhardt EG, Dalby A, Kumar A, Patterson RT (2001) Utility of arcellacean morphotypic variants as pollu-
tion indicators in mine tailing contaminated lakes near Cobalt, Ontario, Canada. Micropaleontology
47:95–95
Roe HM, Charman DJ, Gehrels WR (2002) Fossil testate amoebae in coastal deposits in the UK: implications
for studies of sea-level change. J Quatern Sci 17:411–429
Ruzicka E (1982) Die subfossile Testaceen des Krottensees (Salzburg, Oesterreich). Limnologica (Berlin)
1:49–88
Schmidt AR, von Eynatten H, Wagreich M (2001) The Mesozoic amber of Schliersee (southern Germany) is
Cretaceous in age. Cretaceous Res 22:423–428
Schreve DC, Thomas GN (2001) Critical issues in European quaternary biostratigraphy. Quatern Sci Rev
20:1577–1582
Schönborn W (1962) Z ur Ökologie der sphagnicolen, bryokol en un terrikolen Testaceen. Limnologi ca 1:231–
254
Schönborn W (1963) Die Stratigraphie lebender Testaceen im Sphagnetum der Hochmoore. Limnologica
1:315–321
Schönborn W (1965a) Die Sedimentbewohnenden Testaceen einiger Masurischer Seen. Acta Protozool
3:297–309
Schönborn W (1965b) Studien über die Gattung DiVlugiella (Rhizopoda, Testacea). Limnologica 3:315–328
21
Schönborn W (1966) Testaceen als Bioindikatoren im System der Seetypen Untersuchungen in Masurischen
Seen und im Suwaki-Gebiet (Polen). Limnologica 4:1–11
Schönborn W (1973) Paleolimnological studies of Testacea from Lake-Latnjajaure (Abisko-Region-Swed-
ish-Lapland). Hydrobiologia 42:63–75
Schönborn W (1992a) Adaptive polymorphism in soil-inhabiting testate amoebae (Rhizopoda): its impor-
tance for delimitation and evolution of asexual species. Arch Protistenkd 142:139–155
Schönborn W (1992b) The role of protozoan communities in freshwater and soil ecosystems. Acta Protozool
31:11–18
Schönborn W, Dorfelt H, Foissner W, Krienitz L, Schafer U (1999) A fossilized microcenosis in Triassic
amber. J Eukary Microb 46:571–584
Schönborn W, Flossner D, Proft G (1965) Die Limnologische Characterisirung des Profundals einiger Seen
mit Hilfe von Testaceen-Geimenschaften. Limnologica 3:371–380
Schönborn W, Foissner W, Meisterfeld R (1983) Light and SEM studies of the shell morphology and forma-
tion of races in soil-living Testacea–Proposals of a biometrical characterization of Testacea shells. Pro-
tistologica 19:553–566
Scott DB, Medioli FS (1983) Agglutinated rhizopods in Lake Erie: modern distribution and stratigraphic
implications. J Paleontol 57:809–820
Scott DB, Medioli FS, Schafer CT (2001) Monitoring in coastial environments using foraminifera and theco-
amoebian indicators. Cambridge Unversity Press, Cambridge
Smith HG (1992) Distribution and ecology of the testate rhizopod fauna of the continental Antarctic zone.
Polar Biol 12:629–634
Smith HG (1996) Diversity of Antarctic terrestrial protozoa. Biodivers Conserv 5:1379–1394
Todorov M (1998) Observation on the soil and moss testate amoebae (Protozoa: Rhizopoda) from Pirin
Mountain (Bulgaria). Acta Zool Bulgarica 50:19–29
Tolonen K (1986) Rhizopod analysis. In: Berglund BE (ed) Handbook of holocene palaeoecology and
palaeohydrology. John Wiley and Sons, Chichester, pp 645–666
Tolonen K, Warner BG, Vasander H (1992) Ecology of testaceans (Protozoa, Rhizopoda) in mires in Southern
Finland.1. Autecology. Arch Protistenkd 142:119–138
Tolonen K, Warner BG, Vasander H (1994) Ecology of Testaceans (Protozoa, Rhizopoda) in Mires in Southern
Finland.2. Multivariate-Analysis.Arch Protistenkd 144:97–112
Treonis AM, Lussenhop JF (1997) Rapid response of soil protozoa to elevated CO2. Biol Fertil Soils 25:60–62
Van Oye P (1944) Au sujet de la distribution géographique des Rhizopodes. Biologisch Jaarboek 11:83–91
Vickery E, Charman DJ (2004) Biomonitoring of peatland restoration using testate amoebae. In: Verhoeven
JTA, Dorland E, Coemans M (eds) 7th INTECOL international wetlands conference, vol. Book of
abstracts, Utrecht, NL, 25–30 July 2004, pp 342
Wanner M (1999) A review on the variability of testate amoebae: Methodological approaches, environmental
inXuences and taxonomical implications. Acta Protozool 38:15–29
Wanner M, Dunger W (2001) Biological activity of soils from reclaimed open-cast coal mining areas in
Upper Lusatia using testate amoebae (protists) as indicators. Ecol Eng 17:323–330
Wanner M, Dunger W (2002) Primary immigration and succession of soil organisms on reclaimed opencast
coal mining areas in eastern Germany. Eur J Soil Biol 38:137–143
Wanner M, Esser S, Meisterfeld R (1994) EVects of light, temperature, fertilizers and pesticides on growth of
the common freshwater and soil species Cyclopyxis Kahli (Rhizopoda, Testacealobosia), interactions
and adaptations. Limnologica 24:239–250
Wanner M, Meisterfeld R (1994) EVects of some environmental factors on the shell morphology of testate
amoebae (Rhizopoda, Protozoa). Eur J Protistol 30:191–195
Warner BG (1987) Abundance and diversity of testate amoebae (Rhizopoda, Testacea) in Sphagnum peat-
lands in Southwestern Ontario, Canada. Arch Protistenkd 133:173–189
Warner BG (1990) Testate Amoebae (Protozoa). In: Warner BG (ed) methods in Quaternary ecology, vol.
Reprint Series 5. Geoscience Canada, St. John’s, Newfoundland, pp 65–74
Warner BG, Asada T, Quinn NP (2007) Seasonal inXuences on the ecology of testate amoebae (Protozoa) in
a small Sphagnum peatlands in southern Ontario, Canada. Microb Ecol 54:91–100
Warner BG, Charman DJ (1994) Holocene changes on a Peatland in Northwestern Ontario interpreted from
Testate Amebas (Protozoa) analysis. Boreas 23:270–279
Warner BG, Chmielewski JG (1992) Testate amoebae (Protozoa) as indicators of drainage in a forested mire,
northern Ontario, Canada. Arch Protistenkd 141:179–183
Wilkinson DM (1994) A review of the biogeography of the protozoan genus Nebela in the southern temperate
and Antarctic zones. Area 26:150–157
Wilkinson DM (2001) What is the upper size limit for cosmopolitan distribution in free-living microorgan-
isms? J Biogeograp 28:285–291
22
Wilmshurst JM, McGlone MS, Charman DJ (2002) Holoc ene vegetation and climate change in southern New
Zealand: linkages betw een forest composition and quantitative surface moisture reconstructions from an
ombrogenous bog. J Quatern Sci 17:653–666
Woodland WA, Charman DJ, Sims PC (1998) Quantitative estimates of water tables and soil moisture in
Holocene peatlands from testate amoebae. The Holocene 8:261–273
Wylezich C, Meisterfeld R, Meisterfeld S, Schlegel M (2002) Phylogenetic analyses of small subunit ribo-
somal RNA coding regions reveal a monophyletic lineage of euglyphid testate amoebae (order Euglyph-
ida). J Eukary Microbiol 49:108–118
23
