Timematodea
| Timema | |
|---|---|
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| Timema genevieve on the leaves of chamise (Adenostoma fasciculatum). | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Insecta |
| Order: | Phasmatodea |
| Suborder: | Timematodea |
| Family: | Timematidae |
| Genus: |
Timema Scudder, 1895 |
| Species | |
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21, and see text |
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| Geographical distribution of Timema species in North America (Law & Crespi, 2002). T. morongensis is found west of T. chumash but the extent of its full range is unknown. | |
21, and see text
Timema is a genus of relatively short-bodied, stout stick insects native to the far western United States. The genus was first described in 1895 by Samuel Hubbard Scudder, based on observations of the species Timema californicum.
Compared to other stick insects (order Phasmatodea), the genus Timema is considered basal; that is, the earliest "branch" to diverge from the phylogenetic tree that includes all Phasmatodea. To emphasize this outgroup status, all stick insects not included in Timema are sometimes described as "Euphasmatodea."
Five of the twenty-one species of Timema are parthenogenetic, including two species that have not engaged in sexual reproduction for one million years, the longest known asexual period for any insect.
Timema spp. differ from other Phasmatodea in that their tarsi have three segments rather than five. For stick insects, they have relatively small, stout bodies, so that they look somewhat like earwigs (order Dermaptera).
Timema walking sticks are night-feeders who spend daytime resting on the leaves or bark of the plants they feed on. Timema colors (primarily green, gray, or brown) and patterns (which may be stripes, scales, or dots) match their typical background, a form of crypsis.
In 2008, researchers studying the presence or absence of a dorsal stripe suggested that it has independently evolved several times in Timema species and is an adaptation for crypsis on needle-like leaves. All of the eight Timema species with a dorsal stripe have at least one host plant with needle-like foliage. Of the thirteen unstriped species, seven feed only on broadleaf plants. Four (T. ritensis, T. podura, T. genevieve, and T. coffmani) rest during the day on the host plant's trunk rather than its leaves and have bodies that are brown, gray, or tan. Only two species (T. nakipa and T. boharti) have green unstriped morphs that feed on needle-like foliage; both are generalist feeders that also feed on broadleaf hosts.
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Wikipedia