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March 2009
I was wondering if I could get radiolarian.org members to help me out with an identification of some Nassellarians. These were captured from 400-200m at Station Papa, 50N 145W, in June of 2008. The length is about 0.2mm. There appear to be two types: ones with 3 legs and others with two. The photos are at different focuses, trying to show some of the details. Any help would be greatly appreciated.

Moira Galbraith
Zooplankton Taxonomist
Institute of Ocean Sciences
9860 West Saanich Road
P.O. Box 6000, Sidney, B.C. V8L 4B2
Institut des sciences de la mer,
Bote postale 6000, Sidney, C.-B.

Moira Galbraith 2009/03/20


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Additional photo (1)


Moira Galbraith (2009/03/20)


Additional photo (2)


Moira Galbraith (2009/03/20)


Of the reasonably well established species of Pterocanium these specimens, because of the two equally developed apical horns, would be classified as P. auritum. The thorax looks a bit different than the type material but the difference is probably not of taxonomic significance.

All specimens probably actually have 3 feet (legs) but sometimes one is broken off or just invisible on the other side of the shell.

This species has a catalog entry at rad.org.

Dave Lazarus (2009/03/20)


The double apical horn may indicate a close relationship to P. aurtium, and the thorax is of similar size and shape as that of P. auritum. Sediment fills the thorax making it difficult to compare the meshwork, but pore size could be similar to P. auritum.

The mystery rad photos differ from the images in Radiolaria.org as follows:

Feet are splayed (curved, convex outward) not straight and divergent from base of thorax.

Abdomen is cylindrical with small irregular pores and is not attached to the feet.

These two features could be variants and/or characterize a subspecies. Are the photos representative of a larger population or of just a rare occurrence of the forms?

Richard N. Benson (2009/03/20)


Pterocorys diplotriaena/Pterocorys bicornis


Dear all

A. Pterocorys diplotriaena Dogiel in Dogiel et Reshetnyak 1952

B. Pterocorys bicornis in Dogiel et Reshetnyak 1952 [a primary junior homonym of Popofsky's 1908]

Other info. in Sugiyama et al. (1992).

Cheers, Nori

Noritoshi Suzuki (2009/03/21)



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