Bursal Glands, another female riddle

Akephorus marinus from Pt. Reyes, CA.
Akephorus marinus from Pt. Reyes, CA.

There are lots of features of the carabid female reproductive tract that are obvious in dissections but we still don’t know what they do. Even if we have a good idea of the function in general, e.g. spermatheca to store sperm, we know little about how they work**.

Aassorted glands are chief among these mysterious female widgets. Typical glands are tethered out on a duct of varying length and attach to the spermatheca or on the bursa near the spermatheca. It is presumed that these produce substances to maintain the sperm that the male deposited during mating. This seems to be a reasonable hypothesis.

More mysterious are paired glandular pockets or pouches on the bursa that are found in a number of taxa including species of the Neotropical pterostichine genera Abaris, Pseudabarys and Neotalus; some cicindelines; and the topic of this post, species of Akephorus.

Two western North American Pacific coast beach species, A. marinus and A. obesus, have a prominent, ventral pair of bursal glands. In A. marinus, that has very pale cuticle, you can see the glands as a pair of dark regions when you look at the abdomen ventrally without doing any dissection at all.

Akephorus marinus, ventral view of female abdomen showing bursal glands as dark spots

Akephorus marinus, ventral view of female abdomen showing bursal glands as dark spots

When dissected out, the little sacs are filled with a yellowish-green substance. I did a little initial chemistry work on them, but got no conclusive results. I have kept adults in the lab and could never get them to breed. I think that the intertidal beach habitat is hard to simulate in the lab and the beetles were just never in the mood.

The yellowish-green blobs are the bursal glands of this female Akephorus marinus.

The yellowish-green blobs are the bursal glands of this female Akephorus marinus. This is from an very old camera, so not a good image, but hopefully you get the idea.

I can speculate about all sorts of things they are doing with this glandular substance. Coating eggs to protect them from predation or dessication in the saline environment are possibilities. How widespread is this in dyschirines? I don’t know as I haven’t done a wide survey. I have looked at a few species and not all members of the group have glands.

For now this goes into my bin of enigmas where it will stay, waiting for  someone to pursue these details and solve this mystery.

**[Don’t know carabid female tract morphology? Look here: Liebherr & Will 1998]
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About Kip Will

I'm an insect systematist with expertise in carabid beetles, who is always happiest in the bush.
This entry was posted in Carabids, Coleoptera, Entomology. Bookmark the permalink.

One Response to Bursal Glands, another female riddle

  1. Pingback: Don’t mess with soft-winged flower beetles | pterostichini

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