PRLIMINARY LIST OF SPIDERS AND ASSOCIATED ARTHROPODS OF CALIFORNIA STATE UNIVERSITY, CHICO NATURAL AREAS

BY
HANK GUARISCO
ADJUNCT CURATOR OF ARACHNIDS
STERNBERG MUSEUM OF NATURAL HISTORY
FORT HAYS STATE UNIVERSITY
HAYS, KANSAS 67601

21 September 2005

INTRODUCTION

This is the first report of the identification of spiders and other arthropods collected on California State University, Chico campus and natural areas, Big Chico Creek Ecological Reserve (BCCER) and Eagle Lake Field Station (ELFS), from 4-11 September 2005. A more complete report is planned after all the specimens have been examined.

METHODS

Specimens were collected by myself and Cameron Liggett, educator at the Sternberg Museum of Natural History, by a variety of methods including: hand collecting, using a sweep net and beating net to sample vegetation, and the eyeshine method. The last method involves detecting the eyeshine of hunting spiders that is reflected when a flashlight is shined upon them. Although this is a traditional method for detecting wolf spiders (family Lycosidae) at night, we were able to find other hunting spiders, such as crab spiders (family Thomisidae) by this method as well. Due to the extremely dry weather conditions, only a small number of specimens were observed. After capturing a spider in a small vial, we examined it with a hand lens (10x) to determine if it was an adult or an older juvenile. Since only adults can be reliably identified to species, we released all younger animals. Older juveniles will be raised to maturity before preservation in 80% ethanol.

CHECKLIST OF SPIDERS AND OTHER ARTHROPODS

1) Theatops californiensis Chamberlin 1902: Five specimens of this rather large, eyeless species
of centipede were found under the bark of dead, standing pine trees on BCCER. This situation
was damp and probably provided necessary moisture during the dry conditions. The species
ranges throughout central California and southwest Oregon, and has been collected in leaf
litter (Shelley 2002).

2) Holocnemus pluchei (Scopoli 1763): Numerous examples of this introduced, synanthropic
species were found on campus and on the outside walls of the house on BCCER. This
aggressive invader builds shallow, inverted dome-shaped webs on buildings, railings and
occasionally in shrubs and trees. On campus, these spiders were found in all of these
locations, however at BCCER they appear to be restricted to buildings. None were found in
natural habitats despite extensive searching. A female with an eggsac containing 47 eggs was
collected on a wooden railing on campus on 4 September. The eggs of this species and other
members of the family Pholcidae are carried in the chelicerae. Originating from the
Mediterranean region, this species is widespread in California and is spreading eastward. We
collected some on a building near the Great Salt Lake in Utah during our return trip.

3) Neoscona oaxacensis (Keyserling 1863): This large, dark-gray orbweaver (family Araneidae)
occurs on trees in Lower Bidwell Park and on campus. A female collected on 5 September,
produced a white, fluffy eggsac containing 201 orange eggs two days later. This is wide-
ranging species found throughout the western US, Mexico and Central America, with one or
two records from the eastern US . In California, it has been taken in citris groves (Levi, 1971).

4) Thiodina hespera Richman and Vetter 2004: This pale jumping spider (family Salticidae) was
recognized as a distinct species approximately twenty years ago, but was described and named
just last year (Richman and Vetter 2004). An adult female was collected on an iron fence near
trees on campus. The species is found throughout California, with records in New Mexico,
Arizona and Utah. It is common in the canopy of citrus groves where it consumes a wide
variety of flies and moths. It exhibits the nocturnal resting behavior of hanging suspended
by a silk thread. This keeps the spider out of the way of hunting spiders and ants. Members of
the genus possess a unique set of four bulbous spines on the ventral side of the first tibiae.
These are presumed sensory receptors which have not yet been investigated (Richman and
Vetter 2004).

5) Pardosa californica Keyserling 1887: This small wolf spider (family Lycosidae) was found
near Big Chico Creek on campus. On 4 September, a female carrying an eggsac attached to
spinnerets was collected. The eggsac was lenticular in shape, 3.7 mm in diameter and
contained 24 young and 3 infertile eggs when it was preserved on 16 September. This species
occurs in Oregon, Idaho, California, Utah, Nevada and Mexico (Vogel 2004).

6) Trachelas pacificus Chamberlin and Ivie 1935: An adult female of this species of hunting
spider (family Corinnidae) was collected by beating vegetation on the BCCER on 9
September. It occurs throughout most of California and northern Baja California with a
record in southern Nevada (Platnick and Shadab 1974).

7) Xysticus iviei Schick 1965: An adult male of this California endemic crab spider (family
Thomisidae) was collected on BCCER on 7 September. Two subspecies have been described:
iviei from the Los Angeles area and sierrensis from several localities in the Sierra Mountain
Range. The specimen we collected presumably belongs to the latter subspecies. More
specimens are needed to discern the small differences between the subspecies. They both
occur in montane regions and may be isolated from each other by the Central Valley. This
species is closely related to Xysticus montanensis (Keyserling 1887) which ranges throughout
the western US, Canada and Alaska (Schick 1965).

8) Arctosa littoralis (Hentz 1844): This wide-ranging species of wolf spider (Lycosidae) occurs
throughout southern Canada, the US, Mexico and Central America. The usual habitat of this
nocturnal hunter is sandy beaches (Dondale and Redner 1983). Seven adults of both sexes
were found at night by the eyeshine method along the beach at ELFS on 10 September.

9) Alopecosa kochi (Keyserling 1877): An adult male of this species of wolf spider (Lycosidae)
was found at night in open woods by the eyeshine method at ELFS on 10 September. This
species ranges from southern Canada southward into Baja California and Texas (Dondale and
Redner 1990). Extensive laboratory and field studies of A. kochi were done in California by
Hagstrum (1970a, 1970b, 1971).

10)Sergiolus montanus (Emerton 1890): Remains of an adult male of this hunting spider species
(family Gnaphosidae) was found in the web of a funnelweb spider (Hololena sp.)(family
Agelenidae) in the window casing of the cafeteria building at ELFS on 10 September. It had
presumably wandered into the web and was killed and eaten by its occupant. It ranges
throughout most of the US and Canada, with many records from the western US. Habitat notes
include: “under rocks, reeds, bark…driftwood on beaches, and dry cow feces, in bogs, climax
chaparral, …associated with jack pine, ponderosa pine, scrub oak, aspen, and sage, in and
around buildings, and in stabilized talus at elevations up to 10,200 ft” (Platnick and Shadab
1981).

11)Herpyllus propinquus (Keyserling 1887): An adult female of this species, commonly known
as the western parson spider, was collected from under the bark of a rotten pine stump at
ELFS on 10 September. It is a hunting spider (family Gnaphosidae) and occurs throughout the
western US and Mexico. It has been found in houses, pack rat nests, and associated with oak,
pinyon pine, juniper, yucca, ephedra, nolina, allthorn and mesquite (Platnick and Shadab
1977).

12)Araneus gemmoides (Chamberlin and Ivie 1935): This large, impressive orbweaver (family
Araneidae) occurs throughout most of the northern and western US and southern Canada
(Levi 1971). An adult male and female were found at night on the eaves of buildings at ELFS
on 10 September. The following day, a female was discovered on the underside of a rock
overhang near the beach at Eagle Lake. It is one of three closely related species which have
shoulder humps – point-like projections of the anterio-lateral surface of the abdomen. The
habitat includes: under eaves of houses, on barns, in lodgepole (Pinus contorta) woods, in
cave entrances and rocky ledges and in Manzanita chaparral (1100 meters), San Gabriel and
Los Angeles Counties (Levi 1971).

13)Euryopis formosa Banks 1908: This interesting cobweb spider (family Theridiidae), like other
members of the genus, specializes in ant predation. An adult female was found at BCCER on
9 September. It ranges from central California northward to British Columbia and eastward to
Wyoming (Levi 1954).

DISCUSSION & CONCLUSION

Although this is just a very preliminary list, a number of interesting species have been documented as occurring on California State University, Chico campus and the two natural areas. There are a number of other specimens that I have not yet identified and others are juveniles that are being reared to adulthood. A male pirate spider, Mimetus sp. (family Mimetidae), was found on the eaves of a building at ELFS at night on 10 September. Members of this genus prey on other spiders. Several juvenile crab spiders (Tmarus sp.) were found on shrubs at BCCER at night by the eyeshine method. Their eyes shown bright white instead of blue-green like the wolf spiders’ eyes.

Many of these species occur widely, but a few are local endemics. The eyeless centipede has a relatively localized distribution in central California and SW Oregon, and the crab spider (Xysticus iviei) is also restricted in range. Developing a list of species and recording natural history observations of spiders at ELFS and BCCER will undoubtedly contribute to the knowledge of the biodiversity of these areas, as well as add new information on the biology of these species. Although something of the life habits of the common, wide-ranging species has been published, most species have not been studied. Therefore, there is great potential for student projects which would most likely be published.

LITERATURE CITED

Berman, J.D. and H.W. Levi. 1971. The orb weaver genus Neoscona in North America
(Araneae: Araneidae). Bulletin of the Museum of Comparative Zoology 141(8):465-500.

Dondale, C.D. and J. H. Redner. 1983. Revision of the wolf spiders of the genus Arctosa
C. L. Koch in North and Central America (Araneae: Lycosidae). Journal of Arachnology
11(1):1-30.

Dondale, C.D. and J. H. Redner. 1990. The wolf spiders, nurseryweb spiders, and lynx spiders of
Canada and Alaska (Araneae: Lycosidae, Pisauridae, and Oxyopidae). The insects and
arachnids of Canada, Part 17. Agriculture Canada Publication 1856, 383 pp.

Levi, H.W. 1954. Spiders of the genus Euryopis from North and Central America (Araneae,
Theridiidae). American Museum Novitates 1666:1-48.

Platnick, N.I. and M.U. Shadab. 1974. A revision of the tranquillus and speciosus groups of the
spider genus Trachelas (Araneae, Clubionidae) in North and Central America. American
Museum Novitates 2553:1-34.

Platnick, N.I. and M.U. Shadab. 1977. A revision of the spider genera Herpyllus and
Scotophaeus (Araneae, Gnaphosidae) in North America. Bulletin of the American
Museum of Natural History 159(1):1-44.

Platnick, N.I. and M.U. Shadab. A revision of the spider genus Sergiolus (Araneae,
Gnaphosidae). American Museum Novitates 2717:1-41.

Schick, R.X. 1965. The crab spiders of California (Araneida, Thomisidae). Bulletin of the
American Msueum of Natural History 129(1):1-180.

Shelley, R.M. 2002. A synopsis of the North American centipedes of the Order
Scolopendromorpha (Chilopoda). Virginia Museum of Natural History Memoir 5,
108 pp.