Richard J. Payne

Most eukaryotic microbial biodiversity is undescribed, and most species might be morphologically indistinguishable. Notable exceptions are so-called flagship species which are highly conspicuous and can therefore be used to address biogeographical questions. Here we describe Hyalosphenia papilio subsp. paynei, an arcellinid testate amoeba (Amoebozoa; Arcellinida; Hyalospheniidae) from wet hollows in two Sphagnum peatlands, one in Wales and one in Ireland. Phylogenetic analysis based on Cytochrome C oxidase subunit I (COI) sequencing places it within the lineage A of the H. papilio complex, but it differs from all 13 known H. papilio genetic lineages by its very distinctive, wider than long, morphology. The fact that such a conspicuous taxon was never reported in hundreds of studies published on Holarctic Sphagnum peatlands since Leidy’s description of H. papilio in 1874 suggests that this subspecies has not dispersed and survived beyond Britain and Ireland. Furthermore its genetic similarity to H. papilio s. str. suggests that it has recently evolved. The discovery of this new taxon calls for a more detailed analysis of the morphological, ecological and molecular diversity of the H. papilio species complex.

Testate amoebae are valued for their functional significance and application as indicators of environmental conditions, particularly in peatland ecosystems. Research on testate amoebae has increased dramatically in recent years but there are still large parts of the world which have seen very little research. Here we consider testate amoeba communities of the West Siberian Lowland, the world’s largest peatland region and therefore one of the largest potential habitats for testate amoebae. Extensive sampling identified 89 taxa and showed that testate amoeba communities are structured by their physical and biological environment. We identified significant relationships between amoeba communities and both moisture content and vegetation composition. Despite the assemblages containing many widely-distributed species, some taxa considered typical of peatlands (e.g. Archerella flavum and Hyalosphenia papilio) were comparatively rare or absent, paralleling findings further south in Asia. We suggest that testate amoebae in this region deserve further study and may have useful applications in palaeoecological reconstruction and as bioindicators of the impacts of oil and gas extraction. 

To introduce the special issue this paper reviews the use of protists as bioindicators. Seven key advantages of protist bioindicators are highlighted, namely: environmental sensitivity, functional importance, distribution, size and numbers, response times, ease of analysis and preservation potential. Protist bioindicators have been used in a wide range of contexts from ecosystem restoration to fire history, and particularly environmental pollution. Most major protist groups have been used as bioindicators with diatoms, foraminifera and testate amoebae particularly widely studied. To increase uptake of protist bioindication techniques in routine environmental monitoring technique development should consider the needs of stakeholders from an early stage. Papers in this special issue reflect the diversity of both protist life and possible bioindicator applications.