Psammonobiotus communis

Common Name: Testate amoeba

Synonyms and Other Names:

Psammonobiotus communis photo courtesy of Hugh MacIsaacCopyright Info

Identification: Amoebas in the family Psammonobiotidae have bilaterally symmetric tests (shells) of organic material covered in haphazardly arranged quartz shards. Pseudopods protrude through an opening at one end of the test surrounded by a flared flat collar (Golemansky 1974; Nicholls and MacIsaac 2004; Nicholls 2005). This species displays an oval or circular aboral region (Nicholls and MacIsaac 2004). In P. communis, the angle at which the test and collar join is =5° (Nicholls 2005).

Size: In the Great Lakes this species averages 34 µm in length, 19 µm width and 15 µm height, with a collar diameter of 15–20 µm; however, specimens from around the world vary in length from 23–52 µm

Native Range: P. communis is probably native to the Ponto-Caspian region (Black Sea, Caspian Sea, and Aral Sea basins), but it has been found in every ocean basin of the world (Nicholls and MacIsaac 2004).

Map Key
This map only depicts Great Lakes introductions.

Great Lakes Nonindigenous Occurrences: P. communis was recorded in Lake Huron in 2001 and in Lake Superior, Lake Erie and Lake Ontario in 2002 (Nicholls and MacIsaac 2004).

Table 1. Great Lakes region nonindigenous occurrences, the earliest and latest observations in each state/province, and the tally and names of HUCs with observations†. Names and dates are hyperlinked to their relevant specimen records. The list of references for all nonindigenous occurrences of Psammonobiotus communis are found here.

State/ProvinceYear of earliest observationYear of last observationTotal HUCs with observations†HUCs with observations†

Table last updated 5/25/2018

† Populations may not be currently present.

* HUCs are not listed for areas where the observation(s) cannot be approximated to a HUC (e.g. state centroids or Canadian provinces).

Ecology: Psammonobionts generally occur where interstitial water movement and oxygen supply are adequate. They attach to sand grains by way of the flat collar that is part of the test. The pseudopods protrude from the oral opening of the test for locomotion and feeding. Testate amoebas feed on bacteria and particulate organic matter. P. communis occurs in different regions throughout the world at sand depths ranging from 10–105 cm and at distances of 0–35 m from the shoreline (Laminger 1973; Golemansky 1979; Golemanksy 1994). It is primarily a marine-brackish water species, although it tolerates salinities of 0–37‰ (Chardez 1971; Nicholls and MacIsaac 2004).

Means of Introduction: The most probable vector of introduction to the Great Lakes is ship ballast (Nicholls and MacIsaac 2004).

Status: Established where found. It should be noted that Lake Michigan has not yet been surveyed for this organism (Nicholls and MacIsaac 2004).

Great Lakes Impacts:  

Current research on the environmental impact of Psammonobiotus communis in the Great Lakes is inadequate to support proper assessment.
Psammonobiotus communis was first detected in the Great Lakes through surveys of beach sand in 2001  and 2002, in which this amoeba was the most abundant psammobiont (obligate sand-dwelling) testate rhizopod collected (> 100 specimens total) (Nicholls and MacIsaac 2004). However, compared to abundance in marine beaches, the density of P. communis in the Great Lakes has been relatively low (Nicholls and MacIsaac 2004).

While the impacts of P. communis in the Great Lakes have not yet been studied, testate amoebae tend to prey upon and modify microbial populations, accelerate nutrient cycling, and be consumed by other organisms (e.g., Lousier and Parkinson 1984, Schönborn 1992). Furthermore, selective grazing by testate amoebae may influence microbial community taxonomic composition and metabolic activity (Bonkowski 2004, Sherr et al. 1992).

There is little or no evidence to support that Psammonobiotus communis has significant socio-economic impacts in the Great Lakes.

There is little or no evidence to support that Psammonobiotus communis has significant beneficial effects in the Great Lakes.
In studies outside the Great Lakes, testate amoebae have been used as indicators of ecosystem condition and function (e.g., Fournier et al. 2012).


Regulations (pertaining to the Great Lakes)
There are no known regulations for this species.

Note: Check federal, state/provincial, and local regulations for the most up-to-date information.

There are no known biological control methods for this species.

There are no known physical control methods for this species.

There are no known chemical control methods for this species.

Note: Check state/provincial and local regulations for the most up-to-date information regarding permits for control methods. Follow all label instructions.

Remarks: Given the lack of research effort devoted to testate amoebae to date, this species may have been present in the Great Lakes for many decades prior to its discovery. However, Nicholls and MacIsaac (2004) also remark that the Psammanobiotus species, given their current distribution pattern, may be relatively recent arrivals to the Great Lakes.

References: (click for full references)

Bonkowski, M. 2004. Protozoa and plant growth: the microbial loop in soil revisited. New Phytologist 162: 617–631.

Chardez, D. 1971. A study of thecamoebans in interstitial biotopes, littoral psammites, and marginal subterranean fresh water zones. Bulletin des Recherches Agronomiques de Gembloux 6(3-4):257-268.

Fournier, B., E. Malysheva, Y. Mazei, M. Moretti, and E.A.D. Mitchell. 2012. Toward the use of testate amoeba functional traits as indicator of floodplain restoration success. European Journal of Soil Biology 49: 85-91.

Golemansky, V. 1974. Psammonobiotidae, a new family of thecamoebans (Rhizopoda, Testacea) from supralittoral sea sandstones. Acta Protozoologica 13(11):137-142.

Golemansky, V. 1979. Psammobiotic thecamoebas of the Vietnam coast of the China Sea with description of Cryptodifflugia brevicolla new species Rhizopoda (Arcellinida). Acta Protozoologica 18(2):285-292.

Golemansky, V. G. 1994. Testate amoebas (Rhizopoda: Testacea) from the hygropsammon littoral of three tectonic Macedonian Lakes: Ohrid, Prespa and Doiran. Archiv fuer Protistenkunde 144(3):309-313.

Laminger, H. 1973. Notes on some Testacea (Protozoa, Rhizopoda) of the Yugoslavian Coast of the Adria near Rab. Hydrobiologia 42(1):153-154.

Lousier, J.D., and D. Parkinson. 1984. Annual population dynamics and production ecology of Testacea (Protozoa, Rhizopoda) in an aspen woodland soil. Soil Biology and Biochemistry 16: 103–114.

Nicholls, K. H. 2005. Psammonobiotus dziwnowi and Corythionella georgiana, two new freshwater sand-dwelling testate amoebae (Rhizopoda: Filosea). Acta Protozoologica 44:271-278.

Nicholls, K. H. and H. J. MacIsaac. 2004. Euryhaline, sand-dwelling, testate rhizopods in the Great Lakes. Journal of Great Lakes Research 30(1):123-132.

Schönborn, W. 1992. The role of protozoan communities in freshwater and soil ecosystems. Acta Protozoologica 31: 11–18.

Sherr, B.F., E.B. Sherr, and J. MacDaniel. 1992. Effect of protistan grazing on the frequency of dividing cells in bacterioplankton assemblages. Applied and Environmental Microbiology 58: 2381–2385.

Other Resources:
Author: Kipp, R.M., A.K.Bogdanoff, and A. Fusaro.

Contributing Agencies:

Revision Date: 8/21/2012

Citation for this information:
Kipp, R.M., A.K.Bogdanoff, and A. Fusaro., 2018, Psammonobiotus communis: U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, and NOAA Great Lakes Aquatic Nonindigenous Species Information System, Ann Arbor, MI,, Revision Date: 8/21/2012, Access Date: 7/21/2018

This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.