This small male Timema was found at mid-day, a bit southwest of the summit of Loma Prieta peak, crawling energetically on the clothing of a friend. We had been walking through an area of chaparral (with manzanita, ceanothus, scrub oaks, toyon, and mountain mahogany), intermixed with patches of forest (with redwoods, douglas fir, and tree-sized oaks). This is of relevance, because all these are among the recorded host plants for various species of Timema.

I had seen Timema years before (at Mitchell Canyon on Mt Diablo, and elsewhere) but, though struck by their novelty, I hadn't delved much deeper. However, recently while researching the genus to ID this individual, I became increasingly fascinated by these remarkable creatures...and I was motivated to substantially overhaul the BugGuide info page to document and share some of what I've learned :-).

Using the range maps and host plant lists from various references (see info page)...and, in particular, the interactive Google Maps based set of collection records by Tanja Schwander...I narrowed down the ID to either:

    T. poppense...whose host plants include redwood (Sequoia sempervirens) and douglas fir (Psuedotsuga menziesii); or
    T. californicum...whose host plants include manzanita (Arctostaphylos spp.), ceanothus (Ceanothus spp.), oak (Quercus spp.), mountain mahogony (Cercocarpus spp.), and toyon (Heteromeles arbutifolia).

Records of both species are indicated in the general vicinity of Loma Prieta on the interactive map. Unfortunately, host plant info here doesn't cinch the ID, because all of these genera grow in the area we had been walking through...though near the end of the walk (when the Timema was noticed on my friend) we had most recently been walking through chaparral...which would favor the hosts listed for C. californicum.

However, using the online adaptation of the key in Vickery (1993), and cross-referencing with the pictorial table of terminalia diagrams for all 21 species on the last page of Vickery & Sandoval (2001), I'm fairly confident this is T. californicum. The fact that this male has no dorsal stripes reinforces that conclusion, as the species like T. poppense that feed on plants with needle-like leaves are typically striped. This is presumably because of strong selective pressure for better crypsis, due principally to predation by visually-oriented birds...see this very nice explanation and Sandoval & Crespi (2008) for details.

It may be of interest to some that T. californicum was the first species of Timema described...in 1895, with type locality in the Santa Cruz Mountains.