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September 2003
Dear Colleagues

During our examination of the slides that Dick used in his thesis (1966), we came over this little creature. Have anyone of you seen this guy before?

It was found in the outer part of the Gulf of California, east of La Paz at 1263 m water depth in Station VSE 71, 1-11 cm. The skeleton consist of only one sphere, diameters 140/100 µm (longest/shortest), the meshes are mostly triangular to polygonal, of unequal size. The bars are thin, but some do appear thicker giving the view of scattered ridges with no special pattern on the surface of the lattice sphere.

Very rare. Any help on this one is appreciated.

Kjell and Dick

Kjell Bjørklund and Dick Benson 2003/09/29

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My humble opinion is that the mistery rad of september is no
mystery. I think that it is very close to Cyrtidosphaera reticulata
Haeckel, 1862. This species, reillustrated and redescribed by
Hollande and Enjumet, 1960, p. 87, pl. 31, figs. 1-5; pl. 33, figs.
1-2 under the genus Cenosphaera, has an irregular globular
shell and irregular, usually polygonal meshes, and the bars of
shell are of variable thickness as in your rad. I think that your
species is a Cyrtidosphaera n. sp. Surely, it is not a
Cenosphaera. In fact we do not know what a Cenosphaera is.

Best regards
Paulian Dumitrica

Paulian Dumitrica (2003/10/05)

Dear Kjell and Dick:

It appears that the Mystery Rad is closely related to Arachnocalpis? ovatiretalis Takahashi 1991 (Pl. 46, figs. 12-14). The size of A. ovatiretalis ranges 175-290 mm for length and 105-205 mm for width. Thus, they are larger than the Mystery Rad. They are from the Panama Basin sediment traps. As I mentioned in my 1991 book, the taxonomic position of this species was tentative and thus it can be placed under other taxonomic category in the future studies. At that time I placed it under Arachnocalpis since it has close morphology to that of Arachnocalpis ellipsoides Haeckel 1887 (Pl. 98, fig. 13); thus it was placed under Nassellaria. Certainly, it is possible that this taxon may have an affinity with Plegmosphaera (as Plegmosphaera lepticali Renz 1976) and thus belong to Spumellaria.

I do not agree with the Paulian Dumitrica’s opinion above in that the taxon in question is closely related to Cyrtidosphaera reticulata Haeckel 1862 (Pl. 11, fig. 2). There are two main differences of C. reticulata from the September 2003 Mystery Rad and A. ovatiretalis Takahashi 1991. First, both C. reticulata and the Mystery Rad have two levels of thickness in interconnecting elements which compose an ellipsoidal skeletal body, while C. reticulata has only one kind of element with the same thickness. Second, very sharp angles (<90 degrees) of the intersections of the thicker (or main) elements and also thinner (or sub) elements are the characteristics of the taxa belonging to A. ovatiretalis and the Mystery Rad. Furthermore, they have an elliptical shape of the skeletal body while C. reticulata is spherical. Although I cannot see a basal opening in the pictures of the Mystery Rad, there is a possibility of having such an aperture since the oval body has different diameters in polar regions. Why don’t you examine the G. Calfornia specimens in this regard, which might clarify the matter. Best wishes, Kozo

Kozo Takahashi
Prof. Paleoenvironmental Science
Department of Earth & Planetary Sciences
Graduate School of Sciences
Kyushu University
Hakozaki 6-10-1, Higashi-ku
Fukuoka 812-8581, JAPAN
E-mail: kozo@geo.kyushu-u.ac.jp
Fax: 81-92-642-2686
Phone: 81-92-642-2656

Kozo Takahashi (2003/12/04)

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