After a few months of serious work during which I completed my PhD dissertation defense, I finally have time to blog about spiders again. My friend Andrew Durso recently went to Florida to help collect lizards in a very interesting field study to investigate the evolution of populations on different islands. While Andrew is an accomplished herpetologist, he is interested in natural history in general, and was able to take some spider pictures on a small island in the Matanzas River estuary. This estuary supports a diversity of native habitats and wildlife of national importance.

The spiny-backed orbweaver (Gasteracantha cancriformis) is a pretty spider typically found in woodland edges in the southern United States down into South America. This web-building species, which has six conspicuous abdominal spines, shows interesting geographical variations in color and shape. For instance, the individual photographed by Andrew had a white abdomen and red spines, but individuals that I have seen in Colombia had a yellow abdomen with black spines. It has been suggested that conspicuous colors in spiders may increase their foraging success via the attraction of prey to these colors, but a recent study suggests that this is not the case in Gasteracantha.

White and red Gasteracantha cancriformis, Florida

Yellow and black Gasteracantha cancriformis, Colombia

Andrew also noticed a few Phidippus jumping spiders, which have typical metallic blue-green chelicerae. These individuals appear to be P. regius (the regal jumping spider), which is the largest species of jumping spider in the eastern United States, and relatively common in Florida. Males are black with white markings on the abdomen whereas females can be grey or orange. The male P. regius can be distinguished from the somewhat similar-looking male P. audax by the shape of the posterior abdominal spots, which are oval in P. regius and more linear in P. audax. 

Female P. regius

Male Phidippus, likely P. regius

P. regius is usually found in open habitats such as fields or open woods. Females lay their eggs in thick silken nests under the bark of trees, but cracks and spaces in houses may also provide suitable shelter.

In the evening of Sept. 13th, Ryan and I went for a walk along the Bonneville Shoreline trail, south of Dry Canyon. It had been a nice warm day, and we wanted to spend some time outdoors after being on campus all day.

The Shoreline trail

As I was walking, I noticed a conspicuous silk structure in a sagebrush shrub on the side of the trail. My first thought was that it was a caterpillar tent. Several kinds of caterpillar live in colonies inside silk tents which they use for shelter. However, it seemed a little late in the year for a caterpillar tent, and I hadn’t seen any others in the area. Intrigued, I carefully pulled apart the branches that held the silk structure in place.

The silk structure

I was surprised to find that there were no caterpillars. Instead, a relatively big jumping spider appeared at the bottom of the structure. This spider was a tan color, and its large size made me think it was probably a species in the genus Phidippus. It occurred  to me that this may be Phidippus octopunctatus, a species I had never seen before in the wild, but that had been documented and collected in the area by some of Jim’s previous graduate students. Like this spider, the specimens I had seen in our lab collection lacked any pattern and were tan in color. I later found a publication documenting the use of large silk nests by Phidippus octopunctatus.

Female Phidippus octopunctatus

I soon noticed that this female P. octopunctatus was relatively easy to photograph as she insisted in staying close to her nest. Jumping spiders are usually much more mobile and therefore difficult to photograph. I inspected the silk nest one more time. This time I was able to locate what seemed to be a round egg sac, but I did not look any closer as I did not want to disturb the nest too much.

P. octopunctatus guarding her nest

Further along the trail, I noticed a large orbweb on a fence. It wasn’t too hard to find the owner, a Cat-faced spider (Araneus sp., probably gemmoides) resting on a metal post. The name of this spider originates from the shape of its abdomen, which has two anterior humps that make the spider look like a cat face. Cat-faced spiders are often found near homes, and typically close to a source of light. The idea is that lights attract insects at night, thereby increasing the spider’s food supply.

When we returned to the beginning of the trail, Ryan inspected the large wooden board with the name of the trail. He soon noticed a crab spider hiding between the cracks:

Curious about the identity of this shy crab spider, I gently pushed it out of the crack with a small twig. Thinking I would see a member of the genus Xysticus, I was surprised to notice that this spider appeared to be much flatter and darker in color than the Xysticus spiders I had collected in the area. This spider belonged to a different genus, Bassaniana, also known as the Bark crab spiders. These spiders, which are very flattened, are found almost exclusively on tree bark, wooden fence posts and the like where their color camouflages them. Like other crab spiders, Bassaniana waits to ambush its prey rather than actively hunting it.

Bassaniana out of its hiding spot

Ocha, my Chilean rose tarantula (Grammostola rosea) was given to me last year by my friends Kristal and Josh when they moved out of Logan, as they could not take her with them. Chilean roses are medium-sized tarantulas that originate from desert areas in Chile, such as the Atacama desert, which is the driest desert in the world (parts of this desert have never had rain in recorded history). Females of this species, which can be brown to reddish in color, can live 20 years or more, but I do not know Ocha’s age. She is a pretty brown that blends with the coconut fiber that I use as substrate in her tank. Her movements are relatively slow, and she is an excellent climber who has no trouble climbing up the glass walls of the tank. Since Ocha leaves a trail of silk behind her as she wanders around, the surfaces of the coconut fiber substrate and glass walls in her tank are covered in a thin layer of silk in which the prey I feed her (small arthropods) sometimes get entangled. A very recent study that is worth reading documents that tarantulas produce silk from their feet. I wonder if layers of silk such as the ones I observe in Ocha’s tank occur in the wild, and if they function as a sort of primitive trap that can slow down or even immobilize certain prey items.

Ocha, my Chilean rose tarantula (Grammostola rosea)

Between August 26 and 28, I was in Portal, south-east Arizona, helping my friend Sarah Supp do rodent censuses. Sarah, who is also a graduate student at USU, is interested in long term metacommunity dynamics at this site. The Portal Project is an interesting long-term study that has been active for about 30 years. Our work in the field consisted in placing Sherman traps baited with millet, and collecting and identifying trapped rodents. It was very hot there but being in the desert was a treat in terms of landscape and biology.

Portal field site

Our kitchen and storage area at the site was a small ramada, which also provided a welcome source of shade. I soon noticed against the ramada walls an abundance of tangle webs that contained conspicuous round, cream-colored egg cases made of silk. These cases were being guarded by relatively large, yet very shy female black widows (family Theridiidae, genus Latrodectus), which I assumed belonged to the species hesperus based on geographic location. Females are a shiny black or dark brown with a typical reddish-orange hourglass on the underside, whereas the much smaller males are brown with whitish markings. A female can produce several egg sacs during her life-time (1 to 2 years), and each sac can contain hundreds of eggs.

Female Latrodectus with three egg cases

Female Latrodectus with a large prey item

A common spider at the field site was the orbweaver Neoscona oaxacensis (family Araneidae). The webs were often built between plants and low on the ground so that it was easy to accidentally run into them. This species, also known as the Western Spotted Orbweaver, has a typical leaf-pattern on the back of the abdomen, and the underside consists of a black cross, with four yellow patches in each corner. Notice also the orange spots near the spinnerets. The sternum is yellow, with thick black edges.

Neoscona oaxacensis

The underside of Neoscona oaxacensis

Neoscona oaxacensis with a prey item

It was interesting to notice how Neoscona appeared to be less often in the web during the hottest part of the day. I found a female resting in the shade of a Soaptree Yucca leaf (Yucca elata) to avoid the desert heat and reduce water loss.

Soaptree Yucca in which I found a Neoscona oaxacensis

N. oaxacensis resting in the shade of a Yucca leaf

While I was recording information on trapped rodents, I noticed a spider wandering on my arm. I placed it on my datasheet and took the picture below. I did not know what this spider was at the time as it did not look familiar. I later found out that this spider belongs to the Diguetidae (genus Diguetia), a very exciting find since I had never seen a member of this family before. Diguetids are six-eyed web spiders that live in New World deserts. Diguetia builds a domed sheet web that is topped by a tubular retreat that has incorporated plant material.

Diguetia on my datasheet

At night, Sarah and I searched for scorpions with a UV light (scorpions fluoresce under UV light). Like spiders, scorpions are arachnids and predators. After a few minutes, we detected a glow that indicated the presence of a scorpion. Upon closer inspection, we realized that the scorpion was holding a much younger scorpion in its left claw. We observed the scene for a while but the large scorpion did not move, probably intimidated by our light. Apparently, scorpions do not hesitate to eat their own kind. The  young scorpion was noticeably darker than its predator. It would be interesting to know if it belonged to a different species.

Scorpion cannibalism (UV light)

Scorpion cannibalism (regular flashlight)

On Saturday, after collecting rodents, we took a break and drove to the Southwestern Research Station (SWRS), a year-round field station located 5 miles from Portal, at an elevation of 5400 feet. The SWRS is under the direction of the American Museum of Natural History and gives scientists the opportunity to do research projects in the Chiricahua Mountains. It was a very nice place, with cabins and even a swimming pool and a volley ball court. I was excited to search for spiders here, as the biota here is composed of a unique mix of desert and mountain organisms, including endemic species.

The Southwestern Research Station

Our first spider was a Wolf Spider with a mottled pattern of white and black spots on a rufous-colored abdomen. This spider was wandering about the leaves and fallen pieces of bark on the ground:

On a nearby fallen branch was a different species of Wolf Spider, belonging to the genus Rabidosa (from the latin rabidus, to rave, and the greek osa, full of). There are only five North American species of Rabidosa, each with typical morphological traits. The carapace of Rabid Wolf Spiders has a pair of dark brown/black longitudinal stripes on a pale background color. The dorsum of the abdomen typically consists of a dark brown median stripe flanked by a lighter color. According to Nearctic species of the genus Rabidosa (Araneae:Lycosidae), the species I photographed corresponds to descriptions of Rabidosa santrita, a species with white chevrons on the posterior half of the abdomen. R. santrita is known from desert riparian habitats of Arizona.

Rabidosa santrita climbing up a branch

The rolled-up tip of a plant revealed a dictynid spider in a messy-looking tangle-web, complete with the usual suspended left-overs from previous meals. What a difference compared to the nicely kept webs of araneid spiders!

Dictynid in her web

Further up the trail I found a plump jumping spider in a wooded area not far from the trail edge. She appeared to be a uniform pale yellowish-orange, with perhaps a few darker areas on the abdomen.

An unidentified jumping spider on a piece of bark

As we walked back to the cabins, we found some Linyphiid spiders not far from a stream. These spiders, which are also known as Sheet Weavers, typically hang upside-down in their webs, which look like a suspended sheet, as seen in the pictures below. I do not know what species this is, but it reminds me of the Bowl and Doily spider (Frontinella communis), which it might be closely related to. The webs I found consisted in a sheet under a tangle-web. The tangle-web portion is not very visible in my pictures.

Linyphiid spider waiting under its sheet web

Mom has taken some great spider pictures in the backyard in August. She found a Tegenaria duellica, also known as the Giant House Spider (family Agelenidae) resting on a wall of our house. These spiders like to build funnel-shaped webs and can be quite common around houses, especially in the garage and in the yard. Their webs appear to be much bigger in size when they are built inside the house, probably because those built outside are more exposed to disturbance. At the end of the summer, males wander around in search of females to mate with. This is the time of year when these spiders are often seen walking around the house or found trapped in the bathtub. The closely related Hobo Spider (Tegenaria agrestis) also becomes more visible in houses at the end of summer, for the same reasons.

A male Tegenaria duellica resting on a wall

Mom also found a Pisaurid spider (also called Fishing Spider or Nursery Spider) in a shrub. The species was Pisaura mirabilis. While this spider does not rely on webs to catch prey, mothers build a nursery web in which they guard their offspring. Mom noticed what appeared to be eggs in the web (the web is visible on the upper left corner in the picture). During mating, males of this species offer females a carefully wrapped insect as a nuptial gift.

Female Pisaura mirabilis next to her nursery web

This dark jumping spider (family Salticidae) with a median white stripe on the carapace was photographed on a rock. I have yet to find out what genus it belongs to:

Jumping spider on a rock

Also on a rock was this pretty Wolf Spider (Family Lycosidae) in the genus Pardosa, which had a mottled pattern on the abdomen. There are about 40 species in this genus in Europe. The pattern on the abdomen of Pardosa Wolf Spiders often consists in a series of chevrons with paired black dots, and the legs appear thinner compared to those of other Wolf Spiders.

Pardosa Wolf Spider

The following picture is that of an egg case that mom found under a rock in the backyard.  The egg case, which was inside a shelter made of silk, consisted in a ball of delicate silk threads suspended to the substrate by a thin line at the top. We do not know yet who built this egg case, as the spider could not be photographed.

On August 19th, Ryan and I went for a hike in Dry Canyon, located south of Logan Canyon. We did not walk too far because it was a very hot day and we wanted to take the time to search for interesting subjects to photograph.

Dry Canyon

I searched the many sunflowers along the trail hoping I would find a crab spider sitting on a flower. Crab spiders (family Thomisidae) are ambushers that do not rely on a web to catch prey. Rather, they wait for their prey in strategic places such as flowers or branches. Thomisids that choose to hunt in flowers typically catch flying insects, including bees. These spiders look like crabs because they have a relatively flat body, and two pairs of relatively long front legs. In addition, they are able to move forwards, backwards and sideways! I was able to find a tiny young crab spider sitting on a sunflower. In the picture, the two front pairs of legs are noticeably longer than the other legs.

Young crab spider waiting for prey on a sunflower

Further up the trail, a tree leaf revealed a dictynid spider in her tangle web. I have noticed that dictynid webs usually look very messy, often containing the leftovers of previous meals. It appears that for some reason, these spiders do not care about removing the remains of their prey. Perhaps these left overs are left there because they attract other potential prey items such as flies.

Dictyna in her tangle web

I was happily surprised to find a jumping spider under a nearby leaf. This salticid, probably in the genus Pelegrina, had a dark iridescent abdomen and many white scales on the carapace. This spider had recently caught an ant, which it held in its chelicerae. When my camera got a little too close, the salticid hopped onto a small branch, still holding the ant.

Jumping spider holding a recently captured ant

On the way back down, I noticed a wolf spider (family Lycosidae) resting in a sunny spot on a boulder. This small spider with striped legs was so pale that it was difficult to notice on the background rock. Wolf spiders have four posterior large eyes arranged in two rows and a row of four small anterior eyes. Wolf spiders can be found at night by using a flashlight, because their eyes reflect the light to produce eyeshine, much like a cat’s eyes.

Last week I went to Seattle with Ryan for a family reunion. We spent Thursday afternoon exploring the Washington Park Arboretum, a very pretty park containing all sorts of exotic-looking plants, including magnolias, asiatic maple, rhododendrons and camellias. It didn’t take long to notice that the vegetation supported many spider webs, and that the abundance of spiders was noticeably higher than in Logan.

Washington Park Arboretum

The first spider I found was an araneid of the genus Zygiella, an exciting find since I had never photographed this genus before. Zygiella spiders have a relatively flat, oval abdomen, and eyes that are closely spaced. The back of the abdomen has a leaf-shaped pattern (folium) that is generally white in the front and dark in the back. The orbweb built by adults is interesting because it typically has a missing sector on the upper half, in the direction of the spider’s retreat. The missing sector is where the safety line is located, and this thread leads from the hub of the web to the retreat, as seen in the pictures below.

Zygiella close to her retreat

Zygiella leaving her retreat to go on the safety line

Not far from the Zygiella web, I noticed a silk tent under which a small spider was guarding her eggs, which she kept in a round sac. I only got one picture and did not try too hard to identify her as I didn’t want to disturb her .

A female web spider guarding her eggs

A tangle-web under a leaf revealed a theridiid (probably in the genus Theridion) with a branching pink median stripe on the back of its spherical abdomen. This spider reminds me of Theridion pictum, a species that is found in Europe, North America and Africa.

The most conspicuous spider in the park was the Cross Orbweaver, Araneus diadematus. The webs of this spider were everywhere, even outside the park, in people’s yards. This is the same species than the one mom found in our yard in France (see previous post).

Araneus diadematus

Metellina segmentata

The underside of Metellina, sitting on the empty hub of her web

Mom sent me a picture of a spider that we get every year in our backyard in Brittany, France. This spider, which she photographed in the shrubs by one of the yard fences, is an orb-weaver of the genus Araneus. The species appears to be diadematus (a.k.a. Cross Orbweaver, or Garden Spider), as suggested by the elongated white spots in the front of the abdomen that are arranged in the shape of a cross. A. diadematus is common in Europe, but it can also be found in parts of North America.  Females usually sit face down in the web, or hide in a retreat near the web. The retreat is connected to the web by a special silk line so that the spider can quickly move between the two locations. The abdomen of A. diadematus has two “shoulder humps” in the front, as seen in the picture below. The back of the abdomen has a leaf-shaped pattern (folium) with scalloped margins. This species varies in color and in markings (the “cross” in some individuals is sometimes indistinct).

This morning, Lori Spears, Ben Kuethe and I went to a field located not far from Thatcher, a small town west of Tremonton. Someone had told Lori that there had been large amounts of Argiopes last year in this field in the late summer. Although this genus in the family Araneidae can be quite common in the right type of habitat, I had not seen it yet in the U.S. We followed the instructions to get there, eager to find some big Argiopes.

The field consisted mostly of grasses, thistles, and a few small shrubs:

In 2008 I went to Colombia to visit my family in Bogota and to spend some time in a couple of reserves that belong to the Fundacion ProAves, an NGO dedicated to the conservation of birds and their habitats. I had such an amazing time there that lately I have been longing to go back. While I wait for my next colombian adventure, I decided to post some spider pictures from that trip. The amount and diversity of spiders in these reserves was staggering, making these places a dreamland for arachnologists. There were spiders and spider webs everywhere!

El Paujil is a  reserve dominated by rainforest, located in the departments of Santander and Boyaca. I spent a few days there, dedicating all my time to observing all the plants and animals I could find. I found it exciting to think that there are probably many undescribed species in this part of the world. We spent nights in a nice wooden cabin in the reserve. One of the first spiders I found was the one below, behind the cabin: