Euglypha Rotunda Research Articles

Adaptive Polymorphism in Soil-Inhabiting Testate Amoebae (Rhizopoda): Its Importance for Delimitation and Evolution of Asexual Species

Summary The varieties of the soil-inhabiting testate species Trinema complanatum Penard, 1890, and Euglypha laevis Perty, 1849 (including Euglypha rotunda Wailes & Penard, 1911) are shown to be adaptive morphs of an extreme polymorphism. The morphs represent adaptations in the (upper) litter and the underlying humus horizon in raw humus soils. The morphs of the litter horizon also occur in Sphagnum where the microhabitat structure is similar to that of litter. In clonal cultures the features of the morphs remain relatively constant. Nevertheless, over the course of several months other morphs occur. The morphs could be transformed into each other by selection. In nature these species have a high ability to manoeuvre ecologically. With the help of known genetic mechanisms this paper proposes a genetic interpretation of the polymorphism of asexual protozoan species, which simultaneously gives understanding of the delimitation and evolution of asexual species.

Weed Communities of Cereal Crops Grown on Differently Revegetated Cut-Over Peatland Sites

In the present study, an in situ control experiment was carried out to explore the response of testate amoebae to exogenous nitrogen addition in peatland of Sanjiang Plain. The results showed that nitrogen addition increased the biomass of testate amoebae at lower levels (6 g N · m(-2)), while decreased it at higher levels (> 12 g N · m(-2)). At genus level, nitrogen addition significantly increased the biomass of Arcella and Phryganella, decreased the biomass of Euglypha. Only lower nitrogen addition significantly increased the biomass of Centropyxis. At species level, nitrogen addition significantly decreased the biomass of Euglypha rotunda, while the biomass of either Centropyxis cassis or Phryganella acropodia was increased by a lower nitrogen addition treatment. This study suggested that the response of peatland testate amoebae to nitrogen addition was species specific, which could potentially be used as an indicator for the environment of peatlands.

THE DISTRIBUTION OF TESTATE AMOEBAE (RHIZOPODA: TESTACEA) IN SOME FENS AND BOGS IN NORTHERN ENGLAND

1. Eleven bog and fen areas (330 samples) in Northumberland, Westmorland and Lancashire were examined for testate Protozoa, providing a series of habitats with a pH range 3·2-7·0. 2. In fen conditions, above pH about 5·0, a group of 25 species occurred regularly and almost exclusively. The commonest species were Quadrula symmetrica, Cyphoderia ampulla, C. trochus var. amphoralis, Lesquereusia spiralis, Nebela collaris sensu stricto, N. lageniformis, N. penardiana, Euglypha rotunda, E. ciliata, Pontigulasia bigibbosa, N. tubulosa, N. galeata and Sphenoderia dentata. 3. In bog areas (pH 3·2-4·6), Amphitrema stenostoma, A. wrightianum, Difflugia bacillifera, D. bacillariarum, D. brevicolla, Nebela carinata and possibly Placocista spinosa were characteristic of pools. 4. In acid hummocks, wet areas were dominated by Amphitrema flavum and Hyalosphenia papilio, with Nebela tincta, Arcella catinus, N. militaris, Assulina muscorum, Heleopera rosea and Euglypha strigosa frequently present. Drier areas were dominated by N. tincta, Assulina muscorum, Arcella catinus, Heleopera sylvatica complex, Euglypha strigosa and N. militaris, with Trigonopyxis arcula and Bullinularia indica. 5. A number of species occurred over a wide range of habitats, but usually showed some ‘preference’ for either bog or fen conditions. 6. Fen areas contained more species (Mean 30·1) than areas with pH less than 5·0 (Mean 18·9). 7. The distribution of Testacea in northern England is similar to that recorded in other parts of Europe, but the types of association proposed by Harnisch (1927) are of only limited application.