Ref ID : 2030
Wilfried Schonborn, Wolfgang Petz, Manfred Wanner, and Wilhelm Foissner; Observations on the Morphology and Ecology of the Soil-inhabiting Testate Amoeba Schoenbornia humicola (Schonborn, 1964) Decloitre, 1964 (Protozoa, Rhizopoda). Arch.Protistenk 134:315-330, 1987
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Six geographically widely separated populations of Schoenbornia humicola were investigated. The shell, analyzed by scanning electron microscopy and silver staining, consists of shell platelets (idiosomes) of euglyphids, angular quartz, and amorphous siliceous elements. The foreign idiosomes are picked up from the soil and incorporated. They are not obtained by predation of other testaceans. A comparative biometric analysis of the shells yielded a statistically significant difference in the length of one population. This may be an indication for geographic races in S. humicola. The protoplasm shows a clear zonation as in euglyphids and Nebela species. The nucleus in spherical and has a central nucleolus. The pseudopodium is a very long endolobopodium, used to crawl (as "crawling-pseudopodium") and to feed (as "furcate-pseudopodium"). Extension of the pseudopodium is very rare. Resting stages are cysts and precysts (Kapselstadien). The more frequent resting stages are precysts. During very dry periods a bubble can form between the pseudostome plug and the retracted cytoplasm. On the basis of these observations the genus Schoenbornia can be classified within the family Hyalospheniidae Schulze, subfamily Nebelinae Cash & Hopkinson. Schoenbornia humicola has certain feeding phases. During optimal periods the cell collects humus particles and stores them just outside the pseudostome as a so-called "food-bundle". Humus particles from the food-bundle are continually taken into the cytoplasm; this can take place also during suboptimal periods. This feeding strategy is interpreted as an adaptation to the often quickly changing environmental conditions in the soil. Schoenbornia humicola mainly inhabits the humus layers of the soil and is essentially confined to acid humus. It is an indicator species for moder and raw humus. Its percentage of the entire testacean community amounted maximally to 39.5%. Schoenbornia humicola is slightly stimulated by fertilizers and depressed by lime, if liming causes an excessive increase of the pH of its habitat.