Nov 082015
 

This new mite is obiously a Mesostigmata belonging to the Uropodina Cohort.

I feel a bit uncomfortable with this Polyaspinus, considering that some authors class it in the Polyaspididae family, and others in Trachytidae family. Who owns the truth ? Where is the truth ? M. Kontschan, if you could help us your are welcome !

I read in my favorite book, A Manual of Acarology, that Polyaspinus are denizens of tree holes, forest litter and mostly restricted to the Northern hemisphere. There would be only 7 species for this genus according to the same author. Polyaspinus are phoretic species in deutonymph stage.

 

My species, well, is not fully identified, assuming that I have no key for Europe for this genus… If you happen to have some key for this genus, let us know, and share it ! You can also tell me what is the real species of the specimen I am showing you now. Maybe it is nor Polyaspinus cylindricus (firstly described by Berlese, 1916) neither Polyaspinus nicolae (furtherly described by Hirschmann, 1992).. who knows ? Personnaly I have some doubts when I look at my specimen, and the difficulties is to distinguish when morphological differences are only intra-specific or not !

The vertex ends with a funny shape as visible on the detail of prodorsum, my specimen has two small bulb at the very end of the vertex bearing the setae. But these two setae are not visible on my photo.

Please pay attention to the cerotegument, visible on the cuticle of the body and the legs. This sticking wax agglomerates tiny soil particles and fungus spores. By the way I am personnaly convinced that mites participate in the dispersion of spores !

This Polyaspinus is also a very good example to show what is a called platelet or scutella, a very tiny shields (here in raws in lateral position). If you look carefully you will see two pores and one seta per scutella.

Why I am not convinced for Polyaspinus cylindricus or Polyaspinus nicolae ? Well… for the following reasons :

  • I do not understand exactly the differenciation made by Hirschmann. If we follow the criteria of a central pygidial shield shorter than the lateral ones then it is Polyaspinus nicolae,
  • But in my specimen the scutella, in the two lateral rows and both sides, have the same size but different shapes, this is not the case for the specimen described in my documentation (Annotationes zoologicae et Botanicae N223, Slovenske Narodne Muzeum v Bratislave, Peter Masan, 2001),
  • There are some bulbs at several places on the dorsum of my specimen, I cannot see on drawings of both species (same documentation),
  • The genital shield is also significantly different…

So I submit my case to the world of acarologists, as a bottle in the ocean…

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