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Species Timema genevievae

walkingstick - Timema genevievae - female walkingstick - Timema genevievae - female walkingstick - Timema genevievae - female T. genevieve on Quercus berberidifolia - Timema genevievae - female T. genevieve on Adenostoma fasciculatum - Timema genevievae - female T. genevieve on Adenostoma fasciculatum - Timema genevievae - female T. genevieve on Quercus berberidifolia - Timema genevievae - female Timema - Timema genevievae
Classification
Kingdom Animalia (Animals)
Phylum Arthropoda (Arthropods)
Subphylum Hexapoda (Hexapods)
Class Insecta (Insects)
Order Phasmida (Walkingsticks)
Family Timematidae
Genus Timema
Species genevievae (Timema genevievae)
Synonyms and other taxonomic changes
Timema genevievae Rentz, 1978
Explanation of Names
From Rentz(1978):
"This species is named in honor of Ms. Genevieve Prlain in recognition of her interest in the bionomics of the species."
Identification
Light to dark gray (sometimes nearly blackish) with a mottled pattern. Terminal (10th) tergite slightly emarginate. Eyes are more "produced" (i.e. bulging outwards) than in most other Timema species. All individuals are female (it's a "parthenogenetic" species).
Range
Currently known populations are patchily distributed in the Inner Coast Ranges of central California. They occur north, east, and south of the San Francisco Bay area (i.e. in eastern Lake County; eastern Alameda; western Stanislaus Counties; and San Benito Co.).
Habitat
Canyons in fairly arid, chamise-dominated, chaparral. Curiously, all known occurrences are in areas with serpentinite substrates. No reason is known for this association. Update 4/16/18: BugGuide contributor and National Park Service biologist Paul Johnson found T. genevievae on rhyolite-derived soils...see here.
Food
At present, chamise (Adenostoma fasciculatum) appears to be the exclusive host plant. Although initially discovered on mountain mahogony (Cercocarpus betuloides) and buckbrush (Ceanothus cuneatus), captive larvae fed only on chamise when all three plants were offered. Timema genevievae has also been observed on oak (Quercus spp.).
Remarks
This was the first parthenogenetic (i.e. entirely female) Timema species discovered. Usually adult Timema are found in pairs, with a male riding atop a female ("mate-guarding"). When this species was first discovered, repeated searches yielded only females. When individuals were captured for lab study they laid eggs. And when the eggs hatched and were reared they all turned out to be self-fertile females which also produced female offspring, with no males present.
Four other parthenogenic species of Timema have since been discovered. Because of this Timema have become very useful model organisms for study of various aspects of asexuality and sexuality in evolutionary biology.
Print References
Rentz, D. C. F. (1978). A new parthenogenetic Timema from California. Pan-Pacific Entomologist, 54 (3): 173-177. (Full Text)
Sandoval, C. & B. J. Crespi (2008). Adaptive evolution of cryptic coloration: the shape of host plants and dorsal stripes in Timema walking-sticks. Biol. J. Linn. Soc., 94, pp 1-5 (PDF)
Schwander T. , H. Lee, B.J. Crespi (2011). Molecular evidence for ancient asexuality in Timema stick insects. Curr. Biol., 21, pp. 1129–1134 (Full Text)
Vickery, V. R. (1993). Revision of Timema Scudder (Phasmatoptera: Timematodea) including three new species. Can. Entomol. 125:657–692.
Internet References
NEWS ITEM! (3/29/18): The Timema Discovery Project is an new initiative aiming to harness as many people as possible to collect much needed data for advancing our understanding of Timema...please visit the web site, spread the word, and participate!