Identification, Images, & Information
For Insects, Spiders & Their Kin
For the United States & Canada

Species Caecidotea racovitzai

Great Lakes Waterslater - Caecidotea racovitzai - male Great Lakes Waterslater - Caecidotea racovitzai - male Great Lakes Waterslater - Caecidotea racovitzai
Kingdom Animalia (Animals)
Phylum Arthropoda (Arthropods)
Subphylum Crustacea (Crustaceans)
Class Malacostraca (Malacostracans)
Superorder Peracarida (Marsupial Crustaceans)
Order Isopoda (Isopods)
Suborder Asellota (Asellotes)
Superfamily Aselloidea (Waterslaters)
Family Asellidae (Common Waterslaters)
Genus Caecidotea
No Taxon (forbesi group)
Species racovitzai (Caecidotea racovitzai)
Synonyms and other taxonomic changes
Asellus racovitzai Williams, 1970
Explanation of Names
Caecidotea racovitzai (Williams, 1970)
2 subspecies
The two subspecies (likely to be full species) are mostly told apart by range, although there are some morphological differences too. This should be helpful in the west, where it's unclear which subspecies is introduced (although ssp. racovitzai is at least known from Washington).(1) Those features are (from Williams, 1970):
1. The second (longer) antennae are on average longer in australis compared to the body length
2. The shape of the tip of the male first pleopod is more rounded in australis and more truncate in racovitzai
3. The endite of the male second pleopod's exopod is longer compared to the endopod in australis than in racovitzai and is generally wider than long in australis
4. The male second pleopod's endopod is squatter in australis than in racovitzai
5. The tube at the tip of the male second pleopod's endopod (the cannula) is wider in australis than in racovitzai and generally has a thickened outer lateral margin
disjunct: across the northeastern-north central US and adjacent Canada (ssp racovitzai), and in the far southeastern US (ssp australis). Introduced across the west and in Europe
Epigean (surface waters)
This species is likely to be split into 2 different species in the near future(2)
Works Cited
1.A revision of North American epigean species of Asellus (Crustacea: Isopoda)
W. D. Williams. 1970. Smithsonian Contributions to Zoology.
2.Caecidotea burkensis, new species, a unique subterranean isopod from Burke's Garden, with a synopsis of the biogeography and ...
Salisa L. Lewis, Julian J. Lewis and William Orndorff. 2021. Journal of Cave & Karst Studies.