DAO 112:89-102 (2014)  -  DOI: https://doi.org/10.3354/dao02796

Ciliate species diversity and host-parasitoid codiversification in Pseudocollinia infecting krill, with description of Pseudocollinia similis sp. nov.

D. H. Lynn1,4,*, J. Gómez-Gutiérrez2, M. C. Strüder-Kypke1,5, C. T. Shaw

1Department of Integrative Biology, University of Guelph, Guelph, ON, N1G 2W1, Canada
2Instituto Politécnico Nacional, Centro Interdisciplinario de Ciencias Marinas, Av. IPN s/n, A.P. 592, C.P. 23096, La Paz, Baja California Sur, Mexico
3Hatfield Marine Science Center, 2030 SE Marine Science Drive, Newport, Oregon 97365, USA
4Present address: Department of Zoology, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada 5Present address: Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, N1G 2W1, Canada
*Corresponding author:

ABSTRACT: All parasitoid apostome ciliates infecting krill in the northeastern Pacific are currently assigned to the genus Pseudocollinia. Each krill specimen is apparently infected by only 1 Pseudocollinia species. We describe Pseudocollinia similis sp. nov., discovered infecting the krill Thysanoessa spinifera off Oregon, USA. Its protomite-tomite stage resembles that of P. beringensis, which infects T. inermis (type host species), T. longipes, and T. raschii females in the Bering Sea. These ciliates have similar numbers of somatic kineties (18-21 vs. 16-20) and typically have 3 oral kineties. Furthermore, these 2 apostomes are sister species on gene trees based on sequences of small subunit rRNA (0.06% difference) and cytochrome c oxidase subunit 1 (cox1; 30% difference). P. brintoni and P. oregonensis are closely related as a separate group from P. similis and P. beringensis. The similar tree topologies based on the cox1 sequences of 21 host krill individuals representing 6 krill species (Euphausia pacifica, Nyctiphanes simplex, T. inermis, T. longipes, T. raschii, and T. spinifera) and the apostomes isolated from these krill suggest host-parasitoid codiversification. However, this hypothesis was statistically rejected by an approximately unbiased test in which the host tree topology was used to model parasitoid evolution (p ≤ 0.05).


KEY WORDS: Euphausiids · Apostomatida · Small subunit rRNA · SSUrRNA · Cytochrome c oxidase subunit 1 · cox1 · Oregon


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Cite this article as: Lynn DH, Gómez-Gutiérrez J, Strüder-Kypke MC, Shaw CT (2014) Ciliate species diversity and host-parasitoid codiversification in Pseudocollinia infecting krill, with description of Pseudocollinia similis sp. nov.. Dis Aquat Org 112:89-102. https://doi.org/10.3354/dao02796

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