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Genus Timema

Timema cristinae - female Timema sp. - Timema - male - female unknown - Timema poppense Terminalia  of a 'Striped' and 'Gray' Timema pair on Eriogonum - Timema boharti - male - female Timema - Timema poppense - male - female Second of three distinct sightings of T. californicum on Bay Laurel - Timema californicum - male Timema monikense - Timema chumash - female Female nymph of Timema poppense - Timema poppense - female
Classification
Kingdom Animalia (Animals)
Phylum Arthropoda (Arthropods)
Subphylum Hexapoda (Hexapods)
Class Insecta (Insects)
Order Phasmida (Walkingsticks)
Family Timematidae
Genus Timema
Explanation of Names
Timema Scudder 1895
Numbers
21 spp., of which 20 are in our area(1) (There are at least two more undescribed taxa, one on Pinus flexilis and one on Hesperocyparis sargentii)
Size
♂ 11‒20 mm; ♀ 14‒28 mm
Identification
revised in (2) (more taxa described subsequently)
dependable species ID requires study of the terminalia, especially of the male • helpful views of terminalia: dorsal for males; dorsal, ventral, and lateral for females

Males have asymmetric terminalia with two variously lobed cerci ("claspers"), and a more-or-less ribbon-like projection between them (positioned next to the right cercus and called the "intradextral process"). Figures appear here. Keys refer to left and right cerci using the latin terms "sinistral" and "dextral", respectively.

Female terminalia are symmetric • terminalia of all described species shown at
In bisexual species, adults (as opposed to immature instars or "nymphs") are usually seen paired rather than alone...due to the prevalence of "mate guarding" behavior, in which adult males ride on the backs of adult (or near adult) females for long periods (from hours up to several days). Males are noticeably smaller than females in body size. A rule of thumb given in Sandoval & Vickery (1996) is that a field observation of 5 or more adult females with no males present is a likely indicator of an asexual species.
To each asexual species there corresponds a sexual species whose females are visually indistinguishable:
T. genevievae and T. podura;
T. tahoe and T. bartmani;
T. douglasi and T. poppense;
T. shepardi and T. californicum;
T. monikense and T. cristinae (or T. chumash?)
Range
sw.US and Baja • the map below provides approximate ranges, e.g. of the following species:
T. californicum has records north of San Francisco Bay in Marin Co.;
T. douglasi and T. poppense are recorded from south of San Francisco Bay in the Santa Cruz Mnts;
T. genevievae has records from areas of eastern Lake and Napa counties; and also from San Benito County.
T. chumash is known from the western San Gabriel Mnts, substantially to the northwest of the area mapped for it.

Map from Wikipedia
Habitat
On foliage, twigs, branches or near base of host plants. Sometimes under stones. Host plants mostly associated with chaparral; some with woodlands or forest (e.g. douglas fir, redwood). Green morphs tend to rest on leaves; brown/gray morphs on branches or ground. Unstriped morphs are usually associated with broadleaves (e.g. oaks, ceanothus, manzanita, etc.); striped ones, with plants having needle-like leaves (e.g. chamise, douglas fir, redwood, etc.)
Food
known hosts:
T. bartmani: white fir (Abies concolor)
T. boharti: manzanita (Arctostaphylos spp.), ceanothus (Ceanothus spp.), chamise (Adenostoma fasciculatum), oak (Quercus spp.)
T. californicum: manzanita (Arctostaphylos spp.), ceanothus (Ceanothus spp.), oak (Quercus spp.), mountain mahogony (Cercocarpus spp.), toyon (Heteromeles arbutifolia)
T. chumash: ceanothus (Ceanothus spp.), oak (Quercus spp.), mountain mahogony (Cercocarpus spp.)
T. coffmani: juniper (Juniperus spp.)
T. cristinae: ceanothus (Ceanothus spp.), chamise (Adenostoma fasciculatum), toyon (Heteromeles arbutifolia)
T. dorotheae: ceanothus (Ceanothus spp.)
T. douglasi: douglas fir (Pseudotsuga menziesii)
T. genevievae: chamise (Adenostoma fasciculatum)
T. knulli: coast redwood (Sequoia sempervirens), ceanothus (Ceanothus spp.)
T. landelsense: manzanita (Arctostaphylos spp.)
T. monikense: ceanothus (Ceanothus spp.), mountain mahogony (Cercocarpus spp.)
T. morongense: wild buckwheat (Eriogonum spp.)
T. nakipa: manzanita (Arctostaphylos spp.), ceanothus (Ceanothus spp.), chamise (Adenostoma fasciculatum)
T. nevadense: pinyon pine (Pinus monophylla); juniper (Juniperus spp.)
T. petita: ceanothus (Ceanothus spp.)
T. podura: chamise (Adenostoma fasciculatum), ceanothus (Ceanothus spp.), oak (Quercus spp.), mountain mahogony (Cercocarpus spp.)
T. poppense: douglas fir (Pseudotsuga menziesii), coast redwood (Sequoia sempervirens)
T. ritense: juniper (Juniperus spp.)
T. shepardi: manzanita (Arctostaphylos spp.)
T. tahoe: white fir (Abies concolor)
Life Cycle
In most species, eggs are dropped from branches of host plants. T. douglasi, T. genevievae, T. monikense, T. shepardi, and T. tahoe are parthenogenetic (anomalous males occur in T. monikenesis and T. shepardi). Most of these have a more northerly distribution than their corresponding sexual species; some (e.g. T. genevievae) have been asexually reproducing for over a million years.
during egg-laying, females defecate previously ingested soil, then use their cerci to cover/pack the eggs with soil (this may prevent desiccation, reduce parasitism, and protect from fires common in chaparral habitats); soil is found in the gut of newly hatched larvae and Sandoval has observed that laboratory-hatched eggs of all species survived only when provided with soil from their native locality in the first few days after hatching. It is thought that the soil provides offspring access to microbial symbionts for digestion of host plant foliage. Tachinid flies parasitize larvae of several spp.
Remarks
Timema is the only member of suborder Timematodea, basal to the rest of Phasmida (cladogram)
T. genevievae was the first Timema recognized as parthenogenetic. Rentz noted that while other species known at the time emitted an acrid odor, T. genevievae did not. Weissman suggested that the odor may be associated with mating-related pheromones lost in asexual species.(2)
Print References
D. Arbuthnott, M. G. Elliot, M. A. McPeek, & B. J. Crespi (2010). Divergent patterns of diversification in courtship and genitalic characters of Timema walking-sticks. J. Evolution Biol. 23(7) 1399:1411 (PDF)
Bartman, G. & Brock, P. D. (1995). Observations of the appearance and behavior of species of the stick-insect genus Timema Scudder (Phasmida: Timematodea). Bulletin of the Amateur Entomologist's Society, 54:197-203 (Full Text & photos)
Burrows, Malcolm (2008). Jumping in a wingless stick insect, Timema chumash (Phasmatodea, Timematodea, Timematidae). Jour. Experimental Biol. 211: 1021-1028 (Full Text)
Hebard, M. (1920) The genus Timema Scudder, with the description of a new species, (Orthoptera, Phasmidae, Timeminae). Entomological News, 31 126-132 (Read at BHL)
Hebard, M. (1937) Studies in Orthoptera [...]:Notes and a new species of Timema [...]. T. Amer. Entomol. Soc, 63 (3), pp. 347-350. (Read online)
Law, J. H. & B. J. Crespi (2002). The evolution of geographic parthenogenesis in Timema walking-sticks. Molecular Ecology 11: 1471–1489 (PDF)
Maderspacher, Florian (2011). Asexuality: The Insects that Stick With It. Current Biology, 21 (13) pp. 495-497 (Read online here)
Rentz, D. C. F. (1978). A new parthenogenetic Timema from California. Pan-Pacific Entomologist, 54 (3): 173-177. (Full Text)
Sandoval, C.P. (1994). Differential visual predation on morphs of Timema cristinae (Phasmatodea, Timemidae) and its consequences for host range. Biol. J. Linn. Soc., 52, pp 341-356.
Sandoval, C. P. and Nosil, P. (2005). Counteracting selective regimes and host preference evolution in ecotypes of two species of walking-sticks. Evolution 59:2405-2413 (Full Text)
Sandoval, C.P. and Vickery, V.R. (1996). Timema douglasi (Phasmatoptera:Timematodea), a new parthenogenetic species from southwestern Oregon and northern California, with notes on other species. Can. Entomol. 128:79-84.
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., Crespi B.J. (2009). Multiple direct transitions from sexual reproduction to apomictic parthenogenesis in Timema stick insects. Evolution 63, 84-103. (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)
Schwander T., D. Arbuthnott, R. Gries, G. Gries, P. Nosil, & B. Crespi (2013). Hydrocarbon divergence and reproductive isolation in Timema stick insects. Evolutionary Biology 13:151 (Full Text)
Strohecker, H. F. (1966). New Timema from Nevada and Arizona. Pan-Pacific Entomologist, 42 (1) pp. 25-26. (Full Text)
Tinkham, E. R. (1942). A new californian species of Timema (Phasmodea: Timemidae) with zoogeographical notes. Bull. S. Calif. Acad. Sci. 41(2):72-79. pl. 14 (Read at BHL)
Vickery, V. R. & Sandoval, C. P. (1997). Timema bartmani (Phasmatoptera: Timematodea: Timematidae), a new species from southern California. The Canadian Entomologist 129:933-936
Vickery, V. R. & Sandoval, C. P. (1998). Timema monikensis, Species Nov. (Phasmatoptera: Timemmatidea: Timematidae), a new parthenogenetic species in California. Lyman Ent. Mus. & Res. Lab. Note 22.
Vickery V. R. & C. P. Sandoval (1999a). Two new species of Timema, One Parthenogenetic in California. J. Orthoptera Res. 8 (1) 45:47 (JSTOR)
Vickery V. R. & C. P. Sandoval (1999b). Timema coffmani (Phasmatoptera: Timematodea) a New Species from Arizona and Description of the Female of Timema ritensis. J. Orthoptera Res. 8 (1) 49:52 (JSTOR)
Internet References
iNat pageimages from (3)Image of T. dorothea (ToL) ▪ Images of T. poppense males: [a] · [b]