Environmental Controls on Pore Number in Hyalosphenia papilio: Implications for Paleoenvironmental Reconstruction

Testate amoebae are routinely used as paleoenvironmental indicators. However, considerable variability occurs in test morphology, even within commonly identified taxa. Relationships between morphological variability and environmental conditions might be useful in paleohydrological studies of peatlands, assuming good preservation of characteristics. Hyalosphenia papilio is a common taxon, well preserved in Sphagnum peatlands, that displays variability in the number of pores on the broad side of the test. We assessed whether variability in pore number was related to substrate moisture by comparing the abundance of individuals with different numbers of pores to measured water-table depths at 67 sites in North America. Results indicated that the abundance of individuals with higher numbers of pores increased in wetter conditions. Individuals with 2 pores were relatively widespread, although they dominated drier habitats. Transfer functions developed with and without pore-number quantification suggest that when communities contain abundant individuals with greater than 2 pores, water-table depth reconstructions can be improved by including pore-number information. Results have implications for peatland paleohydrological studies and suggest that greater exploitation of morphological variability could improve testate amoeba-based reconstructions of past environmental change.