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Buprestid - Gyascutus planicosta

Buprestid - Gyascutus planicosta
Borrego Springs, along Henderson Canyon Road, San Diego County, California, USA
June 24, 2005
Size: Body length 22 mm
Every year in June these beetles are common on creosote in the boiling heat. They are VERY wary and hard to get close to. They are covered in a yellow powdery material that comes off pretty easily if roughly handled (for desiccation prevention, I believe). Some of them have these lateral ridges on the elytra and others do not. Wondered if that is a gender distinction? Date above was the date of collection.

After examining this specimen and three others sent to me by Robyn, I can confirm it is Gyascutus planicosta. Variation in the development of the elytral costae has been noted for this species in the latest treatment (Nelson 2000).

Aha! Well now I know.
Thanks, Ted.


...most likely G. planicosta, which is the most abundant and widespread member of the genus. The powdery covering is, as you suspect, probably an adaptation for preventing dessication. The ridges on the elytra (I would call them longitudinal) are not really that variable but might appear so based on how much of the powdery covering has been removed (the ridges will be less distinct in rubbed specimens).

Very nice photo.

You're right about lateral vs
You're right about lateral vs longitudinal -- I should know better as an anatomy instructor ; )

I have several specimens (which I just took a closer look at) and there really seem to be two "morphs," one with distinct ridges and the other without. They are similarly worn. Maybe I can try to photograph the different types.


Two "morphs"...
...might actually represent two species. This is a difficult genus, and there are some other species that might also occur in your area. Post a photo and let's take a look - if I can't make a call perhaps you could send me a few of each for confirmation.

I can take some pictures, but
I can take some pictures, but unfortunately I have not gone digital yet, so it takes a while to get the slides processed, scanned. etc...

Or I might include a couple specimens with the others (the longhorns).

That would be great...
...if you included a few with the longhorns - I should be able to give you firm IDs.

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