Who likes shrews? These mites do!

My friend Allan Lindoe, fossil preparator extraordinaire, lives on an acreage near Athabasca and makes the journey south to Edmonton about once a week to carefully remove rocky matrix from around the skeletons of long-dead fishes, mosasaurs, and dinosaurs. Two cats share his home and frequently bring him presents of wild game. A few weeks ago I washed a mixed bag (literally) of a dozen shrews he had accumulated over the summer and fall of 2015. Chewed-on shrews are not easy to identify unless you know a lot about insectivore teeth, but based on tail length and known distributions of shrew species in Alberta, they were one or more of the masked shrew (Sorex cinereus), Arctic shrew (S. arcticus), pygmy shrew (S. hoyi) and/or dusky shrew (S. monticolus)*. Some of the shrews were rather decomposed, so I wasn’t expecting much from the washings, but I was pleasantly surprised: 6 species of mites! Members of both major lineages were present. From the Acariformes were Prostigmata (Myobiidae, Pygmephoridae and Trombiculidae) and Sarcoptiformes (Glycyphagidae). From the Parasitiformes there were larval hard ticks (Ixodida: Ixodidae) and what look like Melicharidae (Mesostigmata).  Myobiids, trombiculids, and ixodids are parasitic, and the others are all likely just phoretic. Who knew the zoo on shrews? Now you do.

Protomyobia female ex shrew

Protomyobia nr. claparedei female (note egg).

 

Protomyobia ex shrew

Protomyobia nr. claparedei male (note well-sclerotized aedeagus).

 

Protomyobia lv I think A

Larval Protomyobia nr. claparedei (note styletiform chelicerae).

 

pygmephorid ex shrew

Ventral view of one of the many pygmephorids from the shrew washings.

 

pygmephorid ex shrew legs I

Pygmephorid showing modified legs I.

 

chigger ex shrew A

Dorsal view of a shrew chigger (Trombiculidae).

 

chigger ex shrew B

Prodorsal shield of a shrew chigger, showing the posterior pair of trichobothria and single anterior median seta (just the base can be seen here) indicative of the family Trombiculidae, as opposed to members of the Leeuwenhoekiidae, which have two anterior median setae.

 

prob Oryctoxenus A

An Oryctoxenus sp. deutonymph (Glycyphagidae). Anterior is pointing up, and yes, it doesn’t have mouthparts.

 

prob Oryctoxenus B

Posterior hair-clasping structures of an Oryctoxenus deutonymph.

 

ixodid larva ex shrew A

A larval hard tick (Ixodidae).

 

ixodid larva ex shrew B

Retrorse spines on the tick’s hypostome help keep it attached to the host.

 

maybe Proctolaeleps A

Maybe a female Proctolaelaps sp.(Melicharidae). Not in great shape.

 

maybe Proctolaeleps B

The ‘procto’ part of Proctolaelaps refers to the large anal opening, or so the etymological legend goes.

*Smith, H.C. 1993. Alberta Mammals: an Atlas and Guide. The Provincial Museum of Alberta, Edmonton, Alberta.

 

 

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9 comments

    1. The Oryctoxenus individuals on the shrews were in the phoretic deutonymphal stage. They don’t feed but rather use the shrews for transport. Adult (and presumably also the larval, proto- and tritonymphal stages) live in the shrews’ nests and feed on something in there. Most likely fungi or detritus.

  1. The close-up image of the larval tick is good enough, using the recently published Handbook to the Ticks of Canada, to confirm it is the shrew tick, Ixodes soricis Gregson, I’m not sure, but this may be the first record of it from Alberta, other Canadian records being from various areas in British Columbia..

    Confirmed also is your image of a female Proctolaelaps, perhaps P. hypudaei (Oudemans), but more detailed images and observations would be needed to confirm that.

    1. Wow, cool, thanks Evert! I should check with Janet Sperling whether she has any specimens of I. soricis from Alberta in her collection.

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