Thermacarus nevadensis Marshall, 1928

Nevada water mite



Taxonomy & Nomenclature



Conservation Status

Rediscovered? Flagged as GH (Possibly Extinct) by NatureServe

Last record: after 12 July 1972 (Collins et al. 1976:1223)


This species still exists (Heron & Sheffield, 2016), but whether it was actually rediscovered or was mistakenly thought to be extinct but was never really threatened with extinction is unclear at this stage. It was apparently still alive in mid-July 1972 (Collins et al. 1976:1223), and so its hypothetical disappearance prior to hypothetical rediscovery must have taken place quite recently. 



Canada & Nevada (& Utah?), USA


Biology & Ecology










Original scientific description:

Marshall, Ruth. (1928). A New Species of Water Mite from Thermal Springs. Psyche 35: 92-97.


Other references:

Baker, G. T. (1985). External morphology of Thermacarus nevadensis Marshall (Hydracarina: Hydraphantoidea: Thermacaridae). Zoologischer Anzeiger 215(5-6): 391-398.

Brues, Charles T. (1932). Further Studies on the Fauna of North American Hot Springs. Proceedings of the American Academy of Arts and Sciences 67(7): 185-303.

Collins, N. C., Mitchell, R. and Wiegert, R. G. (1976). Functional analysis of a thermal spring ecosystem, with an evaluation of the role of consumers. Ecology 57(6): 1221-1232.

Heron, Jennifer and Sheffield, Cory. (2016). First Canadian record of the water mite Thermacarus nevadensis Marshall, 1928 (Arachnida: Acariformes: Hydrachnidiae: Thermacaridae) from hot springs in British Columbia. Biodiversity Data Journal 4: e9550. doi: 10.3897/BDJ.4.e9550

Nicholas C. Collins, Rodger Mitchell and Richard G. Wiegert. (1976). Functional Analysis of a Thermal Spring Ecosystem, with an Evaluation of the Role of Consumers. Ecology 57(6): 1221-1232. [Abstract]

Mitchell, R. (1962). The growth of Thermacarus nevadensis Marshall (Acari, Hydrachnellae). Zoologischer Anzeiger 168(7-10): 269-275.

Nyquist, D. (1965). An extension of the range of Thermacarus nevadensis Marshall. Proceedings of the Utah Academy of Sciences, Arts, and Letters 42(2): 177. [published in 1966?]

Smith, I. M. and Cook, D. R. (1991). Water mites, pp. 523-592. In: Thorp, J. H. and Covich, A. P. (eds.). Ecology and Classification of North American Freshwater Invertebrates. Academic Press San Diego.

Young, W. C. (1969). Ecological distribution of Hydracarina in north central Colorado. The American Midland Naturalist 82(2): 367-401.


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