Testacea

[Notice]
We reproduce the descriptions of morphology from following books; and we thank following scientists and The Society of Protozoologists (The Journal of Protozoology) for quoting text descriptions from their papers.

Genus list

[A]

Alepiella, Allelogromia, Amphitrema (= Amphytrema), Amphizonella, Amphorellopsis Ampullataria, Antarcella, Apodera, Apogromia, Apolimia, Arcella, Argynnia, Assulina, Averintzia, Awerintzewia

[B]

Bathysiphon, Bullinularia (Syn. Bullinula), Bullinula (See; Bullinularia)

[C]

Campascus, Capsellina, Centropyxiella, Centropyxis (Syn. Echinopyxis, Homoeochlamys), Chardezia, Chlamydonellopsis, Chlamydophrys, Clypeolina, Cochliopodium, Collaripyxidia, Corythionella, Corythionelloides, Cornuapyxis, Corycia, Corythion, Cryptodifflugia, Cucurbitella, Cyclopyxis, Cyphoderia

[D]

Deharvengia, Diaphoropodon (= Diaphorodon), Difflugia, Difflugiella, Diplochlamys, Diplophrys, Distomatopyxis, Ditrema

[E]

Edaphonobiotus, Elaeorhanis, Ellipsopyxella, Ellipsopyxis, Euglypha (Syn. Pareuglypha), Euglyphella, Euglyphellopsis, Euglyphidion, Euglyphinopsis

[F]

Frenzelina

[G]

Geamphorella, Geoplagiopyxis, Geopyxella, Gocevia, Gromia (Syn. Allogromia, Diplogromia, Rhynchogromia)

[H]

Heleopera, Heterolagynion, Hoogenraadia, Hyalosphenia

[J]

Jungia

[L]

Lagenidiopsis, Lagenidiopyxis, Lagenodifflugia, Lamtopyxis, Lamtoquadrula, Lecythium, Leptochlamys, Leptogromia, Lesquerella, Lesquereusia, Lieberkuhnia

[M]

Maghrebia, Matsakision, Messemvriella, Micramphora, Micramphoraeopsis, Microchlamys, Microcometes, Microcorycia, Microgromia, Micropsammella, Micropsammelloides, Microquadrula

[N]

Nadinella, Nebela, Netzelia

[O]

Ogdeniella (Syn. Amphorellopsis), Oopyxis

[P]

Pamphagus, Paracentropyxis, Paramphitrema, Paraquadrula, Pareuglypha, Parmulina, Paulinella, Penardochlamys, Pentagonia, Phryganella, Physochila, Pileolus, Placocista (= Placocysta), Plagiophrys, Plagiopyxis, Planhoogenraadia, Playfairina, Pomoriella, Pontigulasia, Porosia, Proplagiopyxis, Propsammonobiotus, Protocucurbitella, Protoplagiopyxis, Psammonobiotus, Pseudawerintzewia, Pseudochlamys, Pseudocorythion, Pseudocucurbitella, Pseudocyphoderia, Pseudodifflugia, Pseudolagenidiopsis, Pseudonebela, Pseudopontigulasia, Pseudovolutella, Pseudowailesella, Puytoracia, Pyxidicola, Pyxidicula

[Q]

Quadrula, Quadrulella

[R]

Rhabdogromia, Rhogostoma, Rhumbleriella, Rhynchogromia

[S]

Schaudinnula, Schoenboria, Schwabia, Sexangularia, Sphenodera, Sphenoderia, Sudzukiella, Suiadifflugia

[T]

Tracheleuglypha, Trachelocorythion, Tracheuglypha, Trichosphaerium, Trichotaxis, Trigonopyxis, Trinema

[V]

Valkanovia, Voluta, Volutella

[W]

Wailesella, Wailesia

[Z]

Zivkovicia, Zonomyxa

Review on the Variability of Testate Amoebae [ref. ID; 2852 (Wanner 1999)]

Testate amoebae are particularly suitable for the fundamental question, whether and how an organism responds to changing environments. They respond to modified conditions by altering abundance or dominance structure (Lousier 1974; Foissner 1987, 1997) and by changing their shell morphometry (e.g. Wanner and Meisterfeld 1994; Wanner 1994, 1995). The shell architecture of testate amoebae (e.g. shell type and shape, spikes, spines, diaphragms, the aperture) has been commonly used of differentiate between genera or species. Physical limitations, like diffusion-dependent cells size range, surface tension, or biomechanical preconditions of protists skeletons (see Rhumbler 1898; Vogel and Gutmann 1988; Fenchel 1990) and ecological constraints, like habitat adaptation, will also influence the shape of the amoebae shell, resulting in a great variety of different morphs. For taxonomical and ecological reasons it is important to estimate the range and form ("genetic", "nongenetic", as defined in Mayr 1969) of variability within a given taxon. As stressed in Mayr (1969), "the underestimation of individual variation may have caused more than 50% of all synonyms". Furthermore, he stated that "differences between groups of similar specimens ("phena") may reflect either a speices difference or intraspecific variation. Therefore a complete understanding of intraspecific variation is necessary before we are able to separate between possible species." Is for instance the phenomenon of ecomorphosis, the variation caused by the environment (expressed by changes in shell morphology) not only measurable, but also reproducible or even reversible within a few generations? If so, this would give new and fascinating tools for bioindication with testate amoebae, in the laboratory as well as in the field. On the other hand, a strong influence of environmental factors on shell morphometry would lead to serious taxonomic problems, because classification of closely related testate amoebae is primarily based on these characteristics.

General features of testate amoebae

The shell encloses the cell plasma and has usually a single aperture for the pseudopodia. A poteinaceous organic matrix is the basic shell component, either solely or functioning as cement, fixing particles in position (Moraczewski 1969; Saucin-Meulenberg et al. 1973). There are four main shell types: proteinaceous (species with a flexible or rigit shell), calcareous (only two genera), siliceous (species which secrete their own regular siliceous shell platelets, so-called "idiosomes"), and agglutinate (species which include extraneous mineral particles in their shell structure, so-called "xenosomes"). Details are discussed by Grospietsch (1958), Schonborn (1966), Netzel (1983), Ogden and Hedley (1980), Ogden (1984, 1990, 1991), Anderson (1987), and Foissner (1987). Testate amoebae are a polyphyletic, or at least biphyletic, assemblage. The major characteristics, the shell and the pseudopodia, evolved independently representing only convergent features (Hausmann and Hulsmann 1996). This view is strongly supported by molecular data (Bhattacharya et al. 1995; Cavalier-Smith 1997). At present, naked and testate filose amoebae are grouped within the (revised) phylum Rhizopoda, while naked and testate lobose amoebae are grouped into a separate (revised) sarcodine phylum, the Amoebozoa (Cavalier-Smith 1997). This is supported by community structure and biometric data. Foissner (1987) and Wodarz et al. (1992) pointed out that taxa of different origin (e.g. lobose and filose testates) may have a different autecology with individual importance for bioindication. Based on a biometrical analysis of twenty-four soil testate amoebae, Luftenegger et al. (1988) observed that Testaceafilosa have wider ranges in morphometric variation as compared with Testacealobosea.

Methodological Approaches

The basic methodological tools for collecting, preparation, observation and statistics have been discussed in detail by Bonnet (1964), Schonborn (1966), Laminger (1980), Foissner (1987, 1994), Wanner (1991), Aescht and Foissner (1995), and Dunger and Fiedler (1997). Hence in this chapter some specific methodological problems will be highlighted concerning the analysis and interpretation of variabiliy in testate amoebae.

Environmental influences

Taxonomic implications

There are qualitative shell characters useful for distinguishing taxa, as discussed in Ogden and Meisterfeld (1989). Besides biometrical data, surface composition (in combination of knowledge of the general biology and ecology), shell matrix properties, apertural structure, and cytoplasmic features as size and structure of the nucleus, number and location of the nucleolus, are suitable for species differentiation. As shown above, evironmental factors can especially affect shell size and aperture, which are relevant for an exact definition of closely related taxa e.g. ecologic and geographic races (see Wanner 1994; Bobrov et al. 1955; Foissner and Korganova 1995). Thus, identification and assessment of specific environmental factors responsible for the shell variability of distinct species or races are necessary prerequisites for further taxonomical and ecological work on testate amoebae.

Conclusions

"Conventional" bioindication with testate amoebae - using community structure parameters like abundance, dominance, species spectra, and biomass - is successfully established since a long period. As compared to naked amoebae, flagellates, and ciliates, no costly or time-consuming methodology is necessary, since direct observation of an aequeous suspension is sufficient for qualitative and quantitative analysis. With respect to forest soils or agroecosystems, their relatively small species richness, as compared to other protist groups, faciliates practical work on bioindication. However, field investigations based on shell size alterations may not be practicable at the moment, since even few environmental factors produce complex morphometric alterations. In contrast, laboratory tests using clonal cultures of testate amoebae seem to be more promising. Experimentally changed evironmental conditions resulted in distinct alterations in aperture and shell size, which were shown to be highly reproducible and reversible within a few generations. If reliable qualitative shell characteristics are available, shell size variability may cause no severe taxonomic problems, but regarding closely related taxa, where separation occurs mainly by size characteristics, definition of species and bioindication may be impeded. To sum up, intraclonal variability plays an pivotal role in basic and applied research. On one hand, it implies some current taxonomic and ecologic problems, but on the other hand, it offers new and promising possibilities for the future. Based on the above referred data, the following research objective are proposed:

Identification key

  1. Aperture

  2. Material of test construction and test morphology

  3. Pseudopod


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We cannot still accept permission to quote some description from following articles. Please allow us to reproduce. (June 30, 2018)

ref. ID; 654, 2037, 2091, 2241, 3457, 3761, 5772, 7130, 7582, 7609