Dec 042015

This mite was found hitchhiking on a Necrophorus beetle, in French Brittany in 2010.

Well, I am not fully satisfied with these photos but the specialists will anyway probably recognise the Macrocheles glaber group… from the family of Macrochelidae. The problem is that the prepared slide is very slim, it is good to have a global clear view of the mite, but both faces are overlapped, even with higher magnification. When you have no micrometric button, it is difficult to understand, on such photos, if the seta you see is on the dorsum or the ventrum.

Anyway I checked for you the differenciation between the mites of the glaber group (I speak about females here under) :

  • Macrocheles nataliae : setae J5, Z5 and S5 are with distal pilosity, J5 rather fully pilose or serrated
  • Macrocheles glaber : setae J5 are with distal pilosity (or serrated) but Z5 and S5 are smooth
  • Macrocheles perglaber has significant differences in ventral shields but only differential drawings could highlight the differences


When the story becomes complicated, it is with a new description coming from France in 2006 :


It describes a new species called Macrocheles paucipectinatus, but the description is in nearly all points similar to a glaber like Macrocheles and it is stated that :

By several characters, Macrocheles paucipectinatus n. sp. is closed to the glaber group: the well defined procurved line, the pattern on sternal shield, the simple and pilose dorsal setae (S5, Z5 pilose and serrated J5). However simple z4 and r4 get M. paucipectinatus n. sp. different from the standard definition (Walter & Krantz 1992).

This slight difference is not convincing for me, as one can easily observe slight differences in pectinations of setae from one individual to the other pertaining presumably to the same species. But this is only my point of view. I am also slightly dissapointed by the quality of the drawings of the here under referred paper, no description unfortunetly of the chelicera.

One difference I can observe from Macrocheles paucipectinatus with my subject is :

Arched line is short, central part of sternal shield with reticular pattern. Angular line divided in 2 branches posteriorly. Oblique posterior lines glaber-like.

Anyway, to my humble opinion, our subject here is definitly a female of Macrocheles nataliae. One of my references is Fauna Europea, and I do not see any M. paucipectinatus in their list for Macrochelidae. By the way I should jump into TGV to go to Paris check the deposit of types for M. paucipectinatus…

If you read me and are concerned about Macrocheles glaber group (oh my God!), let me know your opinion.

Thanks for your patience reading me.

Nov 252015

I am proud to present you today a case of phoresy on Dorcus parallelipipedus (stag beetle also found as parallelopipedus), family of Lucanidae… Obviously the mite presented here below is a deutonymph and not an adult stage ! It was found on the French territory.

Metagynella carpathica was firstly described by Balogh in 1943. The genera was firstly described by Belese in 1919. To finish with the classification, the family of Metagynuridae was erected by Baker & Wharton in 1952.

The only information I can find on the web concerning this species is the list of 14 species which should be currently identified for this genera… Nothing really more.

This species is probably a paneuropean species, this is my best guess… A nice hypothesis would be to say it follows its host, but I have no specific information to be sure of that. Dorcus Parallelipipedus is actually present in most of the French departments.

One caracteristic of this deutonymph is the “sort of” additionnal genital shield inserted between the anal and the sternal shield as you can see on the last photo. I noticed this intermediate shield only on this Uropodina species for the moment, but maybe some others Uropodina mites, in deutonymph stage, have such one ? This is to be checked…

According to Peter Masan, Dorcus Parallelipipedus is the primary host for the phoresy of Metagynella carpathica. The deutonymph can also use the famous Lucanus servus, as Boeing 747… Indeed, one may raise the question why a so tiny mite needs to use such a big mean of transportation… Obviously this is not a question of weight or size but rather a question of micro biotope this Boeing brings to… You have the answer to that question ? Larvae of Dorcus live in soft decaying wood of broad-leaved trees, is-it then probable to find some Metagynella in this biotope as well ?

One tip to seperate Metagynella carpathica from Metagynella paradoxa Berlese, 1919 : ventral shield setae (around anal opening) are three times longer than the sternal shield setae on Metagynella carpathica, approximatly same size for Metagynella paradoxa, detail which is not obvious on my last photo unfortunately (because of a problem of depth of field). There are obviously some more differences… I hope I will be in position to show you one day a deutonymph of Metagynella paradoxa !

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…

May 102015
Uroobovella pulchella (Berlese, 1904) - deutonymph

Hello world ! This mite is definitely not a parasite but is worth some photos because it has very interesting ornamentations on the whole body. Thanks to the help of Peter Masan, this deutonymph has been identified as Uroobovella pulchella (Berlese, 1904), belonging to the family of Trematuridae. One important thing : they were found […]