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July 2009
I'm writing because I have morphotypes which I don't recognize. Kjell Bjorklund suggested me to put it on as Mystery Rads so the whole radiolarian community can respond. These radiolarians are from recent samples of piston coretop (60) that corresponding to Caribbean Sea Offshore in the Colombian Guajira. The samples are distributed along the bathimetric gradient from shelf (16m) to slope (2500m) with varying (increasing) silica preservation with depth.

Help with species names is very much appreciated.

Regards,
Katherine Andrea León Palma

Katherine Andrea León Palma 2009/08/10

A: Spongurus cf. S. ellipticus (Ehrenberg, 1872)

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Additional photos


B: ???

Katherine Andrea León Palma (2009/07/15)


Additional photos II


C: Siphonosphaera tuburosa ???

Katherine Andrea León Palma (2009/08/10)


There are many 'prunoid' like spumellarians, and when incomplete or broken, as this specimen probably is, it is difficult or impossible to determine the species. Further, many of the Neogene/Recent species have not yet been clearly defined. This specimen most closely resembles either L. weddelium Lazarus et al. 2005 J. Micropal. or the form often labeled Spongurus cf. ellipticus in the literature, based on Nigrini and Moore's catalog (tho it is probably not the same as Ehrenberg's original ellipticus - see Suzuki et al in press for a re-illustration of this latter form).

Dave Lazarus (2009/08/10)


These specimens (clearly not the same as the 'Spongurus cf. ellipticus' above) appear to be ellipsoidal bundles of radially arranged rods. I do not know of rads built this way. Definitely Not a collosphaerid in any case.

Dave Lazarus (2009/08/10)


My Foraminifera colleague Richard Boettcher says he is 80% sure these are statoliths, which turn up commonly in foram preparations The foram people attribute the ones they see in marine samples to sponges, although an online search indicates that objects termed statoliths occur in a wide variety of animals and plants. They are structures involved in gravity-sensing organs, analogous to the balance-sensing otoliths in vertebrate ears.

Stanley Kling (2009/08/11)


Comments to pictures B and C: sponge elements (selenasters or sphaerasters)

Fig. 4. Placospongia melobesioides Gray, SEM images of spicules, holotype BMNH 52.4.1.14. A, tylostyle and developing stages of selenasters (scale 50micrometer). B–C, selenasters (scales: B, 50micrometer; C, 10micrometer). D, spheraster (scale 10micrometer). E, spheres (scale 5micrometer). http://si-pddr.si.edu/dspace/bitstream/10088/7840/1/iz_Ruetzler_2002d.pdf

Please look up the article by Klaus Rützler (see http address in Figure legend at bottom). Klaus Rützler is discussing the Family Placospongiidae Gray, 1867.

Most sponges have different types of spicules, so this is just an example.
However, I am as, Stan Kling, confident that what is depicted as B and C are sponge elements. In the north Atlantic and the Barents Sea the genus Geodia is quite abundant, a genus that have numerous sphaerical or oval skeletal elements, that erroneously have been reported as radiolarians in some publications. Their size are often about 60-80 micrometers.

Kjell R. Bjřrklund (2009/08/28)



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