GBCT Beetle #1: Crossidius hirtipes immaculatus

In my recent Great Basin Collecting Trip (GBCT) overview, I provided some general comments about the longhorned beetles in the genus Crossidius that were the focus of the trip and, in many cases, photographs of the habitats in which the beetles were found. I didn’t show many photos of the beetles themselves, however, and such will be the focus of a series of posts intended to provide a little more detail about the individual taxa that we encountered. I was fortunate to obtain photographs of every species and subspecies that we found and, thus, will include these in the posts as well. Many of the images are bona fide, in situ field photographs—i.e., the beetles were photographed in their native habitat on the host plants on which they were encountered (although in most cases the plant part on which the beetle was resting was detached from the plant and hand-held to control the background). Some beetles were too active to photograph at the time they were encountered, in which case they were confined with their host and photographed that evening after they had settled down—either with a natural background or in front of blue-colored fabric intended to simulate a sky background. I believe in full disclosure when it comes to nature photography and will indicate if photos are anything other than in situ field photographs.

Crossidius hirtipes immaculatus (male) | Davis Creek Park, Washoe Co., Nevada

Crossidius hirtipes immaculatus (male) | Davis Creek Park, Washoe Co., Nevada

No need, however, for such disclosures in this first post of the series, as these images are true field photographs of Crossidius hirtipes immaculatus—the first longhorned beetle that we encountered on the trip. One of 16 currently recognized subspecies of C. hirtipes, populations assignable to this taxon are rather widely distributed from eastern Oregon to east-central California across northern Nevada (Linsley & Chemsak 1961). We found good numbers of these beetles in west-central Nevada at Davis Creek Regional Park (Washoe Co.) on flower heads of what I believe to be Chrysothamnus viscidiflorus. According to Linsley & Chemsak (1961), this subspecies differs from the nominotypical subspecies (the latter occurring further north in Oregon and Washington) by its paler coloration and (as the subspecies epithet indicates) reduced maculations of the elytra. In males the elytra are often completely immaculate (above), while in females the maculae are reduced to a narrow sutural stripe (below). A similar subspecies, C. h. setosus, occurs at the western edge of the distribution of C. h. immaculatus in east-central California (Nevada Co.) but is distinguished by the presence of short, dark, bristle-like hairs interspersed with longer hairs on the antennal scape—these are lacking in C. h. immaculatus.

Crossidius hirtipes immaculatus (female) | Davis Creek Park, Washoe Co., Nevada

Crossidius h. immaculatus (female) | Davis Creek Park, Washoe Co., Nevada

In addition to C. viscidiflorus were healthy stands of Ericameria nauseosa, but as was the case with nearly all subsequent C. hirtipes encounters adults were found almost exclusively on flower heads of the former. This contrasts somewhat with published information that suggests the species breeds as larvae in the roots only of C. viscidiflorus but readily feeds as adults on flowers of E. nauseosa. We saw several dozen individuals at this site, but only a small handful were found on E. nauseosa. We also noted the early exit of the adults, which started disappearing after ~5 pm local time. We suspect they crawl down to the base of the plant to spend the night hiding among debris, although we were unable to find any adults on the lower stems or around the base of the plants despite careful searches.

REFERENCE:

Linsley, E. G. & J. A. Chemsak. 1961. A distributional and taxonomic study of the genus Crossidius (Coleoptera, Cerambycidae). Miscellaneous Publications of the Entomological Society of America 3(2):25–64 + 3 color plates.

Copyright © Ted C. MacRae 2013

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About Ted C. MacRae

Ted C. MacRae is a research entomologist by vocation and beetle taxonomist by avocation. Areas of expertise in the latter include worldwide jewel beetles (Buprestidae) and North American longhorned beetles (Cerambycidae). More recent work has focused on North American tiger beetles (Cicindelidae) and their distribution, ecology, and conservation.
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6 Responses to GBCT Beetle #1: Crossidius hirtipes immaculatus

  1. Moe says:

    Soldier beetles are great-looking bugs. Great photos!

  2. D. Christopher Rogers says:

    Hiyer, Ted!

    Just back from collecting tiger beetles in the Nebraska Sandhills. I enjoyed this and the previous post. You visited many of my old stomping grounds. I miss that country. Like you, I have never found C.punctatus to be abundant. The biggest numbers I found were between Lake Siskiyou and the highway, in Siskiyou, County, California. I also found a few around Honey Lake in Lassen County California.

    When you were in Washoe County, did you find any Stenostrophia tribalteata sierrae Linsley & Chemsak, 1976? I found them in reasonable numbers in spring and fall along the southeast side of Washoe Lake.

    Cheers,
    Christopher

    • Hi Christopher – shoot, no I didn’t get any Stenostrophia tribalteata sierrae. But now I know a good spot for it the next time I’m out there :)

      Jeff and I have already been talking about a Crossidius² trip to sample the Central Valley and Cascade populations we missed on this last one. Fall is a great time for trips like this, and it’s kinda nice to be able to focus on specific taxa rather than looking for anything and everything.

      I have some great memories from the Nebraska Sandhills!

      • D. Christopher Rogers says:

        Very nice! The Central valley ones are much more difficult to get . . . lots of private property and vigilant locals. Let me know if you need some good localities or contacts. You can collect on the Carrizo Plain, but you must get a permit. It would be nice if there were signs or something to the effect that a permit was required on that piece of BLM land, but you just have to know. The permit is free, but if you do not have it they come down on you like the hammer of God. They had even threatened to confiscate my vehicle, let alone my collecting equipment. I made up for it my providing tons of free data to them. What I went through for shrimp and tiger beetles!

  3. Pingback: Copulating robber flies, with snack - Colin Purrington

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