Erugomicula, a new genus of Arcellinida (testate lobose amoebae)

Abstract

Testate lobose amoebae of the order Arcellinida are a diverse, cosmopolitan group of shelled protists found in many environments, including freshwater habitats, peatlands, and soils. Their decay-resistant tests make them an important fossil group for reconstructing Quaternary environments. Within the family Difflugidae Stein, 1859 more than 300 species and 200 sub-species have been attributed to the genus Difflugia Leclerc, 1815. Although carried out on only a few taxa, molecular evidence has demonstrated that test morphology is more important than test composition in categorizing distinct taxa within the Arcellinida. The type species of Difflugia, D. proteiformis Lamarck, 1816, is characterized by a terminal aperture and an elongate acuminate test. The morphology of D. proteiformis is vastly different from most species assigned to Difflugia, explaining its polyphyletic status. We reclassify Difflugia bidens Penard, 1902 as type species of Erugomicula, a new genus within the Difflugidae, which is distinguished from other taxa within Difflugia by its broad, ovoid test, and distinct compression. Based on the compressed morphology of the test, which is not a characteristic of the Difflugiidae, we tentatively assign Erugomicula to the family Hyalospheniidae. Nawaf A. Nasser. Ottawa-Carleton Geoscience Centre and Department of Earth Sciences, Carleton University, Ottawa K1S 5B6, Canada. nawaf.nasser@carleton.ca Braden R.B. Gregory. Ottawa-Carleton Geoscience Centre and Department of Earth Sciences, Carleton University, Ottawa K1S 5B6, Canada. GregorBRB@gmail.com David Singer. Department of Zoology, Institute of Biosciences, University of São Paulo, São Paulo, Brazil and Ottawa-Carleton Geoscience Centre and Department of Earth Sciences, Carleton University, Ottawa K1S 5B6, Canada. david.singer.bio@outlook.com R. Timothy Patterson. Ottawa-Carleton Geoscience Centre and Department of Earth Sciences, Carleton University, Ottawa K1S 5B6, Canada. tim.patterson@carleton.ca Helen M. Roe. School of Natural and Built Environments, Queen’s University Belfast, Belfast, United Kingdom, BT7 1NN. h.roe@qub.ac.uk NASSER ET AL.: Erugomicula, A NEW GENUS OF ARCELLINIDA 2