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January 2001
The mystery Radiolaria of the month is a Phaeodaria, which can not be unequivocally assigned to Euphysetta or Challengeron. Its shell is egg shaped with regular pores of equal pore size. It has a pronounced aboral spine, which is not articulated and two oral spines of equal length, which are articulated. The aboral spine is about the length of the shell or even longer. Beside these spines there are two minor spines, one at each side of the shell. The scale bar indicates 50 µm.

The species was found in the plankton from the Sea of Okhotsk. It
occurred most commonly in a station above the Kuril Basin at 48°41.9'N and 151°29.0'E between 50 and 130 m depth.

Anja-Pia Nimmergut 2001/01/31

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Challengeron or Euphysetta will be the genera you have to consider as far as I am concerned. Even if your specimen show similarities with f. ex. Challengeron diodon, the similarity is only related to the aboral part of the skeleton, beyond that your specimen show no sign of being a Challengeron species, as the characteristic peristome is missing!!! We are then left with Euphysetta, and it does not fit that genus definition either. However, which other genus to place it in? Euphysetta is defined with four oral teeth, one big and three smaller. Your specimen show TWO large articulated feet. How is it, do you not see two smaller feet as f.ex. in Euphysetta elegans or E. nathorsti? I would be surprised if you do not have 4 oral spines or feet!!! You must present us with an additional picture showing the other side of the brim on the oral pore/opening, just to demonstrate the absence or presence of two additional smaller feet, that, if present, should not be articulated. If these 4 spines can be demonstrated you have an Euphysetta species, but it does not fit the original definition of the genus. An emmendation will then be the only solution to your problem, Euphysetta with one or two articulated main feet and two or three smaller, not articulated terminal feet around the oral pore/opening. If you after an reexamination still have only TWO MAIN ARTICULATED FEET, then I do not know what to do but to erect a new genus. Can you present more data the spine ornamentation around the oralbrim?

Kjell R. Bjørklund (2001/01/06)

The specimen looks similar to Challengeron neptuni, except that it (the mystery rad) has two articulated oral spines.

Jane K. Dolven (2001/01/18)

Anja, Jane do point at a species that you are familiar with. On your photos that you discussed with me at InterRad, and photos that you have sent me, show very clearly that the two main spines are articulated. This is why I have trouble when you use the Challengeron genus, where no, according to the definition, articulated spines are present.

One possibility might be: Borgert (1892) did not notice the articulated feet, and therefore placed it among the challengerids. Your species is identical to Borgert’s C. neptuni except for the articulated feet. Could we suggest Euphysetta neptuni?? Could that solve the problem?!?!
You have confirmed that the feet/spines are articulated!!! You have also confirmed that you have not observed any additional spines, so we are still in conflict with the original definition of Euphysetta: one large articulated spine and three smaller, not articulated, spines. May be that you have to adjust the definition of Euphysetta to get room for your species? I still cannot see where it will fit in the present phaeodarian system!

If Kozo Takahashi and Stan Kling do browse these pages, could you guys share with us your impression on this matter???

Kjell R. Bjørklund (2001/01/18)

January 2001 mystery

Challengeron neptuni Borgert 1892

I don't have much to add to the above, but here is what there is. I believe the mystery phaeodarian is a medusettid. It looks very similar to other species that have been placed in Euphysetta, although of course it doesn't have the right number of feet for that genus as currently defined. I agree with Kjell and Jane that it may well be conspecific with Borgert's Challengeron neptuni, and that Borgert may have overlooked the articulated feet. Borgert's line drawing illustration of C. neptuni has all the key elements - the 2 feet (oral spines) with branches, the aboral spine, and the lateral spines. However, he also shows 2 accessory oral spines that do not seem to show on Anja's photo. And there could be some question as to the placement of the feet, which appear to be symmetrically opposed in Anja's specimen and perhaps paired on one side in Borget's illustration. Also, the main branches on the feet (Borgert shows also some tiny thorns on the feet) extend in the same circular direction in Anja's, whereas Borgert's seem to be aimed at one another. Finally, Borgert shows more that 2 lateral (Anja's "minor") spines. It would be helpful to know what the variability of Anja's specimens is in regard to these subtle features. So to sum up, I agree with Kjell that the mystery species probably is Borgert's C. neptuni and that it should go either in an emended Euphysetta or a new genus. I suppose I would favor the conservative choice of putting it in the existing genus Euphysetta. To save others from wondering what C. neptuni looks like, I am posting an illustration from Borgert (1928, not the original 1892 publication) that Kjell kindly e-mailed me.

Stanley A. Kling (2001/01/26)

I made an error, which I communicated to Stan Kling!

In 1929 Schröder published his article: Die nordischen Spumellarien: Teil I: Unterlegion Sphaerocollida. In Nordisches Plankton, Zoologischer Teil, Siebenter Band: Protozoa. Pp. 91-120.

In this 1929 volume there is an index of earlier radiolarian contributions in this series. By a mistake the title page of the 1929 (but I wrote 1928) volume was acting as a cover on my Borgert (1901) reprint.

Therefore when Stan say Borgert (1928, not the original 1892) it should read:
Borgert (1901, not the original 1892).

1) Borgert (1928 does not exist)!
2) Borgert (1928) should be Borgert (1901). SORRY!!

Kjell R. Bjørklund (2001/01/29)

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