Arizona/Nevada, April 16-22, 2008REVSYS volunteer Zach Valois (undergraduate, Salt Lake Community College) and friend Kelsey Neeley traveled over 2,200 miles in an attempt to collect five major target species of scorpions for the REVSYS project. We collected 8+ species, representing five genera. A total of 70+ specimens were collected and deposited in the AMNH collection. We worked in several different biotic communities and desert ecosystems. From Western Colorado Plateau highlands, to lower Sonoran desertscrub. Partially funded by the REVSYS NSF grant, this trip was successful and yielded some great finds; including Paruroctonus ammonastes, new localities of members of Vaejovis from the Vorhesi group, and topotypes of Smeringurus mesaensis.

Participants:

Zachary J. Valois SLCCKelsey Neeley

Upper Sonoran desert of Maricopa County ascending into chaparral, elevation around 4500 ft. Habitat of Vaejovis spinigerus, Centruroides sculpturatus, and Aphonopelma cf. chalcodes.

Forest road leading into the high pine and manzanita forests. Notice the difference in vegetation of the north facing (right) and south facing slopes (left). It would be interesting to take a detailed look at the differences in invertebrate species composition and density within two slopes. Presumably, overall invertebrate fauna would be more successful on the north facing slopes. Where as you can see, vegetation is thicker and more speciose than the drier south facing slope.

Adult Aphonopelma cf. chalcodes female.

Almost three hours of off-road driving took us to the ridge of the Mazatzal Mountains. Beautiful pine forest around 7000 ft. The photo on the bottom left is the trail that we were forced to drive up in order to leave the location during the previous trip while collecting in this region. We were very lucky to get out with minimal damage.

A female (left) and male (right) Vaejovis sp., in the vorhiesi group, individuals were found within a couple yards of the opening of a mine.

Gila County

We came across some interesting bats in this mine, picture here is Lasiurus zanthinus. Bottom left: Female Vaejovis sp. found about 80 ft. from the mine entrance. Bottom right: A new dwarf theraphosid species from this region seems to aggregate in these open rocky patches surrounded by Yucca and Manzanita. This burrow placement makes excavation incredibly difficult and may be an adaptation to avoid predation and competition from other fossorial Aranae. The choice of microhabitat may also be an adaptation to avoid spring snow melt runoff, as the rocks and plant roots between the rocks may add structure and stability to the soil.

Horned lizard (Phrynosoma sp.)

Typical Sonoran Desert, descending from the pine forests. These lower areas provide alluvial fans and washes that provide great habitat for Hadrurus arizonensis. Vaejovis confusus, Vaejovis spinigerus, and Centruroides sculpturatus also inhabit this zone.

Maricopa County

The upper chaparral riparian habitat pictured above yielded extremely high numbers of Centruroides sculpturatus-in addition to a lot of hungry mosquitos. The old highway that runs along Sycamore Creek has been shut down and blocked off, so that meant lots of extra hiking to find a spot in which we could climb down the rock walls into the creek. We ended up hiking about five miles up and down the creek. Below pictured is a Centruroides sculpturatus female.

Maricopa County

Vaejovis sp. vorhiesi group.

Vaejovis spinigerus.

The overlook into the creek, about 80 feet down.

Adult female Vaejovis spinigeris.

A Centruroides sculpturatus female that has captured a moth.

On the north end of Mesa, we picked up topotype specimens of Smeringurus mesaensis. Unique lower Sonoran desert and grassland. Sandy ridgelines deposited by the flow of the Salt River provided ideal habitat for S. mesaensis, in addition to Hadrurus arizonensis, Vaejovis spinigerus and Vaejovis confusus. Although with exception to S. mesaensis, these species were found more abundant in harder packed, rockier areas. This could simply be a result of exploitation competition among the scorpion guild. S. mesaensis seems to simply dominate these soft, sandy areas.

Adult female Smeringurus mesaensis.

In areas with creosote, S. mesaensis almost always occupied a burrow at the base of a bush.

S. mesaensis. The burrow of this individual is located directly at the base of the bush.

Sub-adult female S. mesaensis feeding on a weevilAdult female H. arizonensis.

An adult S. mesaensis eating, these were commonly seen being preyed upon.

Mohave County

Heading north-west we begin to enter the Mojave-Sonoran desertscrub transition. Occasional patches of isolated dunes were of particular interest, concerning our target for this region. Only one area along the east bank of the Colorado River did we find the elusive scorpion, Paruroctonus ammonastes. S. mesaensis was extremely abundant in every area that had even remotely soft substratum. The combined activity of ATV and OHV use and urban sprawl seem to only provide better conditions for S. mesaensis. S. mesaensis being an already highly predacious, successful medium sized scorpion thrives in disturbed areas. V. confusus and H. arizonensis are found in the sandy habitat, but are of higher density in rockier areas, such as this wash pictured in the bottom right photo. There is likely some Serradigitus species in these rocky foothills.

S. mesaensis burrows.

Zach sorting and preserving specimens.

Adult male Vaejovis confusus.

Adult female Paruroctonus ammonastes.

Adult female P. ammonastes.Adult female S. mesaensis.

Keying specimens in the field.

Female Vaejovis confusus.

A third instar male Smeringurus mesaensis.

Male Hadrurus arizonensis.

Male Serradigitus wupatkiensis.

With a slight rise in elevation and latitude, the vegetation of these arid footslopes begin to change. Compare the dominating sage and yucca basin in this photo with the that on the open scrub in top left photo.

We give special thanks to Lorenzo Prendini, Jeremy Huff, David Sissom, Warren Savary,Christian Elowsky, Joe Bigelow, Darrin Vernier, the Salt River Pima-Maricopa Indian Community and their Police Department, Kelsey Neeley, and foremost Kari McWest .