[Note: Photos by Tom Chester; commentary by Aaron Schusteff]
The photos in this post are from my botanist friend, Tom Chester, who along with field companions Nancy Accola & Pat Matthews made this sighting during a botanical survey in the Borrego Desert. Details sandwiched by lines below are paraphrased from a portion of the remarks I received from Tom:
At 1:23 p.m. the group noticed termites were swarming. Tom recalled termites often swarm right after a winter rain about midday...though here in the desert the swarm density was only about one tenth of what he'd experienced in the past around his home in coastal chaparral habitat of San Diego County. Then at 3:12 p.m. the group noticed a remarkably large, red, unfamiliar arthropod crawling with purpose on the ground. It was close to the size of a female velvet ant
, perhaps a half-inch long, but looked arachnid-like. No one in the group had ever seen such a thing before.
Once home with reference resources available, members of the group settled on an ID of "giant red velvet mite" (genus Dinothrombium
)...based on the excellent agreement in size, distinctive red velvety appearance, desert habitat, and emergence right after a rain with swarming termites...as described in the following passage from Evans(1)
"Giant red velvet mites appear in desert regions after summer rains. Their surface activity coincides with the nuptial flights of their prey, winged ants and termites. For most of the year they remain dormant in subterranean silk-lined chambers. Size to 3/8 inch (10 mm)"
This is the westernmost post of Dinothrombium
on BugGuide to date. Currently, the only other CA post is from the Algodones Dunes, which are in far southeastern CA...not very distant from the Arizona border. There are only 2 species listed under Dinothrombium
for our area in the catalog by Mąkol(2)
(Newell and Tevis, 1960). Distribution: California
(Banks, 1910). Distribution: Arizona (originally described here
Based on the distribution info above, the best candidate for Toms' find would seem to be Dinothrombium pandorae
. Unfortunately, neither of the papers elaborating on that species are freely accessible on the web (i.e. Newell and Tevis (1960)
and Tevis and Newell(1962)
Another species of possible relevance here was originally described as Trombidium magnificum
by LeConte in 1852; later referred to as Dinothrombium magnificum
by Newell and Tevis in 1960; and listed as Phyllotrombidium magnificum
...but placed there under "Taxa incertae sedis". Mąkol(2)
gives its distribution as "New Mexico, Texas"...but Art Evans used that name for a post from the Patagonia Mountains of Arizona
(south of Tucson) that looks and sounds similar to Tom's Anza-Borrego find.
Some interesting details of the biology of Dinothrombium
can be found on the associated BugGuide info page