Month: March 2016

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.



A Less Notorious Bee Mite

The mite Varroa destructor has become famous in the wake of colony collapse disorder as a nasty parasite of the domestic honey bee Apis mellifera. But it is not the only bee-associated member of the family Varroidae, nor is A. mellifera the only host of varroids. Last week a former honours student of mine, Dr. Geoff Williams, sent me specimens of Euvarroa from a nest of the dwarf honey bee Apis florea Fabricius from just north of Chiang Mai in Thailand, where they had been collected by a local student, Patcharin Phokasem.

Like Varroa, Euvarroa are very large, heavily sclerotized mites. The ones that Geoff sent were 1 mm long: five Notoedres from a mangy squirrel skin could lie nose-to-tail on the venter of one Euvarroa.

Euvarroa with Notoedres

Euvarroa sinhai is a big mite, shown here with a 200 um long Notoedres for scale.

There are two named species in the genus Euvarroa, E. sinhai Delfinado & Baker and E. wongsirii Lekprayoon & Tangkanasing. Euvarroa sinhai is associated with Apis florea, whereas E. wongsirii is found on A. andreniformis Smith.  The species differ in general body shape (very triangular for E. wongsirii) and length:width ratio for the anal plate (longer than wide in E. sinhai, the opposite for E. wongsirii)*. Based on these host and morphological features, the mites from Geoff are E. sinhai.

I don’t think that much is known of the biology of either Euvarroa species, but they are very spiffy-looking mites. Here are some closer views of parts of their anatomy.

Euvarroa chelicera

The bee-piercing chelicerae of Euvarroa sinhai.

Euvarroa peritreme

Euvarroa sinhai‘s u-shaped peritreme; stigma to the upper left.

Euvarroa ambulacrum

“My, what big ambulacra you have!” “All the better for holding onto bees, my dear.”

*Lekprayoon, C. and P. Tangkanasing. 1991. Euvarroa wongsirii, a new species of bee mite from Thailand. International Journal of Acarology 17: 255–258.