Jan 212016

Our today parasite has, as indicated by the species name, a quite circular appearance. Unfortunatly, I cannot show you a global view of this species. I am really sorry but it was to big for my lowest magnification objective !

Zonurobia circularis Lawrence 1935 belongs to the family of Pterygosomatidae and has been found on Platysaurus guttatus, the dwarf flat lizard. It can be found in Nord Transvaal in South Africa.

This is probable that the author of the prepared slide is Frank J. Radowsky (1929-2010), but I am not sure. Anyway this specimen and slide is now part of the French collection MNHN, Paris.

This prepared slide is really good and we can observe many details. I particularly appreciate the scale-like setae, which reminds me the scales of a butterfly. Have you ever observed butterfly scales in a microscope ?

Gnathosoma reminds me a tick, with hypostome and chelicerae, but it is far from an Ixodida !


I draw your attention on peritremal tubes araising on each side of the gnathosoma. I made specially two photographies of the gnathosoma, with two different focusses.

By the way, I recommend you the following publication which shows some very good drawings of this species :


If you observe carefully the description and drawings which are made of Zonurobia circularis, you may notice that my photos are showing exactly the same configuration of articles and setae…

This publication, here above in reference, mentions that Lawrence has described 5 different types of Zonurobia circularis, and this species would probably require some deaper analysis linked with the type of hosts… Zonurobia is considered by Jack (1964) as near to Pterygosoma genera. One may wonder if some described species of Pterygosoma could not be in reality Zonurobia !

I propose you to compare both genera with the following post showing Pterygosoma transvaalense.

We are at you disposal to make such analysis if you can provide us some specimens of these nice parasites !

Oct 212015

Hello again with another mount from the collection of MNHN in Paris. The shown slide has the following references :

  • Name of species : Axonopsis romijni (no longer valid at present)
  • Locality : lake “du grand Laoucien” in France
  • Date of collection : 1927
  • Reference of slide : 19C4
  • Collection : C.M. (Understand C. Motas)
  • Sex : male

It is a real pitty that the medium used for the mount is nearly never indicated. In this case it is pretty well preserved for a mount done in 1927.

According to A Checklist of the water mites of France(Acari: Hydrachnidia) of Harry SMIT and Reinhard GERECKE, this species is present in France in Ardèche, in Pyrénées-Orientales and in Var. It is a member of Aturidae family ad Aturinae subfamily.

I wonder what is the origin of Axonopsis name ? This could be due to the fact that Axonopsis has a dark spot (like an eye “ops”) in the axis (“axo”) of the animal ? Your opinion is welcome.


The exact naming of the species was recently Axonopsis (Hexaxonopsis) romijni Viets, 1923 (same reference as here under published in 2010), but according to this recent publication (2015) :

Revision of the status of some genus-level water mite taxa in the families Pionidae Thor, 1900, Aturidae Thor, 1900, and Nudomideopsidae Smith, 1990 (Acari: Hydrachnidiae) – IAN M. SMITH, DAVID R. COOK & REINHARD GERECKE

We are proposing here that a number of taxa in the families Pionidae, Aturidae (subfamilies Axonopsinae and Aturinae), and Nudomideopsidae that have been treated as subgenera in the recent literature should be elevated to full generic rank to reflect the diversity, morphological distinctness, relationships, and apparent ages of the species groups they comprise.

… the name of the species has been moved to Paraxonopsis romijni. Paraxonopsis is elevated in
rank from subgenera to full genera, and the former sub-genera seems to have changed by the way…

More information on the site of collection here. C. Motas studied the fauna of this lake and published the following book : Contribution à la connaissance des hydracariens français particulièrement du Sud-Est de la France, C. Motas, Travaux du Laboratoire d’Hydrobiologie et de Pisciculture de l’Université de Grenoble, 1928″.

In the title of this article, I mention probable parasite of chironomids, because it seems to be an accepted hypothesis unless there is no real proof of evidence of that. Parasitism on chironomids is probable, as many related genera include chironomid-parasitic species. In all known cases, it is the larva that parasitizes the insect host. This subject is still to be studied !

Here is a link of one of my colleagues with a live image of an Aturidae.

For this post, my thanks goes to Professor Gerecke and MNHN, Paris.

Sep 082015

I am back with another mount from the collection of National Museum of Natural History in Paris. The shown slide has the following references :

  • Name of species : Pterygosoma rubi (not valid)
  • Name of host : Agama atricolis (quoted with one “l” for atricollis on the slide)
  • Locality : Bukavu (Democratic Republic of Congo)
  • Reference of slide : 8F7
  • From the medical laboratory of Kivu

First of all, Agama atricollis is now a synonym of Acanthocercus atricollis. It is an Agamid lizard living in South East of Africa (South Africa, Namibia, Zimbabwe, Malawi…).

Secondly, Pterygosoma rubi is not currently a valid species. After interrogation of Michel Bertrand, a French acarologist who studies Pterygosomatidae, it seems that the illustrated species is rather Pterygosoma transvaalense described by Lawrence in 1935. This is the only known parasiting mite of Acanthocercus atricollis. New species of Pterygosomatidae are still being discovered on reptiles.

I propose you another example of Pterygosomatidae with Zonurobia circularis.

If you happen to collect such parasites on lizards, Agamidae, or other reptiles, we would be happy to receive some samples for identification and photography.

Thanks again to the NMNH in Paris !


Jul 282015
Arrenurus sp - parasite on Irish damselfly Coenagrion lunulatum

Hello world ! I am the first surprised to publish photos of an Hydrachnidia. A colleague, on a French forum on insects, sent me some samples of water mite larvae collected on the Irish damselfly (Coenagrion lunulatum in the family of Coenagrionidae), in the French vulcan park in the very center of France. We made […]