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 :
- TWO NEW SPECIES OF MACROCHELES FROM FRANCE (MESOSTIGMATA: MACROCHELIDAE) by J. NIOGRET , A. NICOT & M. BERTRAND (Accepted October 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.