Monday, November 25, 2019

Case of the Week 570

This week's case was generously donated by Dave Neitzel at the Minnesota Department of Health. A mutant headless tick! Wouldn't it be great if they were all this way?

Can anyone identify the genus of this tick?

11 comments:

Marc Couturier said...

That inverted anal groove is screaming Ixodes to me.

Blaine A. Mathison said...

Headless? Must be Ichabod scapularis!

Sam said...

In both images the left and right ticks are male and female (respectively) of the genus Ixodes. They are of likely relevance to this blog as they are vectors of Babesia species. They are also vectors of Borrelia burgdorferi (the aetiological agent of Lyme disease).

dirus said...

I agree, Ixodes scapularis. This will be covered in my next lecture for our D.V.M. students.

Anonymous said...

There is no doubt that the tick is a female tick of the genus Ixodes. Its anal groove being anterior to the anal pore is definite evidence to the identification. The previous answers are not only educational and scientific, they are also very comical. I particularly love the Ichabod crane answer.
From Saigon with love,
Florida Fan

Anonymous said...

I love your answer! I live by Sleepy Hollow, NY, and by Mathissen Park, NY.

Makrone said...

Both are female Ixodes scapularis ticks. Not only the capitulum, but also the genital pore appear to be absent in the right one. The first pair of legs seems to be prolonged or it is deceptive because of missing mouthparts. There is also a sclerotic structure between the first pair of legs. Interesting abnormality
Is it from the field collection or lab colony?

Old One said...

Was this "Headless Horseman" ambulatory ? Many times Ixodes will be submitted with mouthparts torn off due to deeply deposited cementum. This tick looks like it molted that way. If that is the case, it had mouthparts in both the larval and nymphal stages which allowed it to feed and develop into a mature female. It only became "headless" due to an anomalous final ecdysis. Could this be the definition of Hell. Having sensory organs (on the forelegs) but no mouthparts to feed.

The structure commonly called the head of the tick is really mouthparts consisting of Hypostome, Chelicera, and Palps mounted on a Capitulum. In ticks and mites the body segments are blended. This is why the eyes of ticks (if they have them) are found halfway down the body. Do ticks really have a head? I don't know. Thats a question for the Morphologist.

Here in Minnesota we also have Ixodes cookei which is easily differentiated from I. scapularis. I. cookei has a diamond shaped scutum with unique ridges, and shorter palps.

Jose Q said...

This is a hard tick of the genus Ixodes. These pictures are neat.

William Sears said...

ixodes

Old One said...

For those of you interested in Ixodes and love a good conspiracy May I suggest "Bitten" by Kris Newby.

My wife who would rather make me breakfast in bed than read a book, gives this work 2 thumbs up.