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Atlanta californiensis Seapy & Richter, 1993

Atlanta californiensis is one of only two atlantid species that have a temperate water distribution. This species is known from the Eastern North Pacific Ocean (Seapy and Richter, 1993) and Southern Mexican Pacific Ocean (Moreno-Alcantara et al. 2014) and is the most abundant atlantid species found in the California Current system.

  • Shell is moderately small with a maximum of 4⅔ whorls and maximum a diameter of 3.5 mm.

  • The whorl sutures are shallow and the shell surface is smooth (no ornamentation). Sutures can be violet or clear.

  • The shell spire has 3–3¼ whorls and is low and globular in shape. The spire colour varies, it can be light yellow, light brown, violet, dark and mottled yellow-brown or dark brown.

  • The 4th whorl expands rapidly and the last whorl is encircled by a high keel that is truncated along the anterior margin. The keel inserts between the last and penultimate whorls in shells over ~2 mm.

  • The keel base may be red-brown or orange-brown.

  • Umbilicus is wide but narrows rapidly at the penultimate whorl.

  • Eyes type b, operculum type c, radula type I.


Similar species:




Further reading:


Moreno-Alcántara, M., Aceves-Medina, G., Angulocampillo, O. & Murad-Serrano, J.P. 2014. Holoplanktonic molluscs (Gastropoda : Pterotracheoidea, Thecosomata and Gymnosomata) from the southern Mexican Pacific. Journal of Molluscan Studies, 80: 131–138.


Seapy, R.R. 2011. Atlantidae. In: Tree of life web project. Available at accessed 1 April 2017.


Seapy, R.R., Richter, G., 1993. Atlanta californiensis, a new species of atlantid heteropod (Mollusca: Gastropoda) from the California Current. The Veliger 36, 389–398.


Wall-Palmer, D., Burridge, A.K., Goetze, E., Stokvis, F., Janssen, A.W., Mekkes, L., Moreno-Alcántara, M., Bednaršek, N., Schiøtte, T., Vinther Sørensen, M., Smart, C.W., Peijnenburg, K.T.C.A. Biogeography and genetic diversity of the atlantid heteropods. Progress in Oceanography, 160:1–25. doi: 10.1016/j.pocean.2017.11.004

Wall-Palmer, D., Metcalfe, B., Leng, M.J., Sloane, H.J., Ganssen, G., Vinayachandran, P.N., Smart, C.W. Vertical distribution and diurnal migration of atlantid heteropods. Marine Ecology Progress Series, 587: 1–15. doi: 10.3354/meps12464.

Wall-Palmer, D., Smart, C.W., Kirby, R., Hart, M.B., Peijnenburg, K.T.C.A., Janssen, A. 2016. A review of the ecology, palaeontology and distribution of atlantid heteropods (Caenogastropoda: Pterotracheoidea: Atlantidae). Journal of Molluscan Studies, 1-14.

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