Yuri Mazei1 and Alan Warren2
1 Department of Zoology and Ecology, Penza State University, Penza, Russia
2 Department of Life Sciences, Natural History Museum, London, UK
Summary
We review the species of Difflugia with a shell that is pyriform or elongate, based
primarily on examinations of two collections in the Natural History Museum, London, UK: (i)
Penard’s collection of balsam-mounted microscope slides, and (ii) Ogden’s scanning electron
micrographs and shell measurements. We discuss taxa grouped into seven species complexes, namely
Difflugia oblonga Ehrenberg,
1838, Difflugia pyriformis Perty, 1849, Difflugia bryophila (Penard, 1902) Jung,
1942, Difflugia linearis (Penard, 1890) Gautier-Lièvre et Thomas, 1958, Difflugia gigantea
(Chardez, 1967) Ogden et Fairman, 1979, Difflugia petricola Cash, 1909, and Difflugia lanceolata
Penard, 1890.
Within the D. oblonga-complex we: (i) distinguish as a separate taxon the typical form of D.
oblonga Ehrenberg, 1838; (ii) synonymise D. parva (Thomas, 1954) Ogden, 1983, D. lacustris (Penard,
1899) Ogden, 1983, D. bacillifera Penard,
1890, D. oblonga var. incondita Gauthier-Lièvre et Thomas, 1958, and D. oblonga
f. cyphodera Jung, 1942 with D. oblonga. Within the D. pyriformis-complex we: (i) distinguish as
separate taxa the typical form of D. pyriformis Perty, 1849, as well as D. capreolata Penard, 1902,
and (ii) synonymise D. cylindrus (Thomas, 1953) Ogden, 1983 with D. pyriformis Perty, 1849. Within
the D. bryophila-complex we: (i) distinguish as a separate taxon D. bryophila (Penard, 1902) Jung,
1942, and (ii) synonymise D. gassowskii (Gassowsky, 1936) Ogden, 1983 with D. bryophila. Within the
D. linearis-complex we: (i) distinguish as a separate taxon D. linearis (Penard,
1890) Gautier-Lièvre et Thomas, 1958, and (ii) synonymise D. paulii Ogden, 1983
and D. nebeloďdes Gauthier-Lièvre and Thomas, 1958 with D. linearis. Within the D. gigantea-complex
we: (i) distinguish as a separate taxon the typical form of D. gigantea (Chardez, 1967) Ogden et
Fairman, 1979, and (ii) discuss the validity of D. oblonga var. angusticollis Štĕpánek, 1952, and
D. oblonga var. stepaneki (Štĕpánek,
1952) Decloitre. Within the D. petricola-complex we accept D. petricola Cash, 1909 as a valid
species and suggest its possible relationships with other Difflugia species.
Within the D. lanceolata-complex we accept D. lanceolata Penard, 1890 as a valid
species and illustrate its variability based on C.G. Ogden’s SEM micrographs.
As in the first part of this series of papers in which we taxonomically revise the genus
Difflugia we conclude that, based on current knowledge, it is unclear whether these
species complexes represent single, highly polymorphic species, or groups of sibling
species. Further studies based on a combination of morphometric, ultrastructural
(SEM), molecular, and environmental data are needed in order to characterize these
species complexes in more detail and thus resolve their systematics.
Key words: Difflugia, morphospecies, species complex, taxonomic revision, testate amoebae
Address for correspondence: Yuri Mazei. Department of Zoology and Ecology, Penza State University,
Krasnaya str. 40, 440026 Penza, Russia;
e-mail: yurimazei@mail.ru
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