flipping rocks at 4000 feet

A spot that I’d not visited in several months was Molino Canyon Vista, so I took a trip there yesterday. It was partly sunny and breezy, with temperatures around 70°F. What’s not to love about that? The seasonal stream was really moving, culminating in a series of pretty little waterfalls that cascade down the canyon. I’m not entirely sure what the bedrock in this area is, but it’s metamorphic, and is likely gneiss. It’s lightweight and seems to cleave in relatively flat pieces, making extremely good hiding places for invertebrates.

After crossing the stream, I headed upland. The first rock I turned sheltered a lovely female Phidippus carneus. This was the only jumping spider I found in this outing.

As far as spiders go, I did find a couple different species. I saw quite a few crab spiders of the same or similar species, both males and females. Unlike the jumping spider, which had created a web to overwinter in, the crab spiders simply cling to the underside of their rock shelter.

The crab spider pictured above, Xysticus sp., is a male, as indicated by the shape of the pedipalps, and was not impressed with my camera lens. His posture in the first photo is a defensive stance. The cryptic coloration on this spider is really quite wonderful, and matches the rock perfectly.

This female crab spider might be the same species as the male pictured prior.

The other two spiders I found were a thin-legged wolf spider (Pardosa sp.) and what appears to be a type of cellar spider (Pholcidae) from the genus Psilochorus. The wolf spider was found under a rock very close to the seasonal stream — which is no surprise, as this genus of wolf spiders is often found near water.

The arachnid I found the most of was a species of Opiliones, or harvestman. I’m not sure of its identification, perhaps from the genus Leiobunum. Turns out, identifying harvestmen is really tricky! These might have been juvenile instars, which makes identification even more challenging. This was a smaller, squatter species with legs shorter than the daddy long-legs I would see in Michigan.

Edit 1/22/2020: all of these harvestmen belong to the genus Protolophus, a rather small group of Opiliones. Thank you for the ID!

While turning rocks near the stream, I accidentally disturbed a harvestman that was in the middle of molting. Not wanting to injure it when I replaced the rock, I let it continue the process in my hand before placing it in a sheltered spot to finish hardening its fresh exoskeleton.

Mites are a fun find, especially if they’re big! I found two large mites beneath neighboring rocks, both very similar in size, just differing colors. They might be the same species.

Edit 1/22/2020: both of these mites are in the family Erythraeidae, and both might be in the genus Callidosoma. Thank you for the ID!

What else did I find? Three scorpions! Two of them were small, perhaps three-quarters of an inch in length (not including the tail), and the third one was absolutely tiny, maybe a fourth of an inch.

Edit 1/22/2020: both of these scorpions are the Superstition Mountains scorpion, Superstitionia donensis. Thank you for the ID!

I did find one pseudoscorpion on this outing. It appeared to be a different species than the ones I found in our neighborhood last week.

Edit 1/22/2020: this pseudoscorpion is in the superfamily Neobisioidea. Thank you for the ID!

All these wonderful arachnids aside, I uncovered some insects, as well! There were a couple of surprises.

One of four small Tenebrionid beetles found under a rock. They seem to overwinter gregariously.
I definitely did not expect to find a colorful caterpillar overwintering under a rock. It appears to be the larva of a butterfly from the family Nymphalidae. Any help with identification is welcome!
Another, much duller, mystery caterpillar. I found several of this species.

Near the seasonal stream, I found both bristletails and what appeared to be some sort of small winter stonefly (family Capniidae). It’s worth mentioning that in the water — which was quite cold, due to it being snowmelt! — I saw some small diving beetles and a tiny species of water strider.

As I headed back toward my car, carefully navigating my way past thorny acacia bushes, I noticed a honeybee — and then another — and then another. “That’s a lot of bees,” I said to myself — and then I realized, about a foot and a half away, there was a basketball-sized mass of swarming feral honeybees. Needless to say, I quickly retreated! They didn’t seem to care about my presence, so I did crawl closer to take some photographs. Arizona has a problem with aggressive feral honeybees (“Africanized” bees), so I was careful to move along and leave them be. But what an interesting phenomenon!

All in all, it was a great couple hours spent looking for cryptic arthropods. As always, I was careful when replacing rocks, making sure to angle them in such a way that no critters were squished. It’s really incredible just how much is out there, hiding beneath the ground we walk over. Next time you’re outside, flip a few stones and see what you find — just make sure to replace them when you’re done.

2 Comments

  1. Hi Jorie, Enjoyed taking a walk with you. Nice pictures of the critters and the swarm of bees. Uncle Bob

    Sent from Mail for Windows 10

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