Crossidius coralinus caeruleipennis | Owens Valley nr. Bishop, California

Before driving up into the White Mountains to look for Crossidius hirtipes nubilus and see the grotesquely beautiful trees at Ancient Bristlecone Pine Forest, we made a short two-mile drive north of our hotel in Bishop, California to try our hand with a C. coralinus subspecies that I referred tangentially in my previous post—C. c. caeruleipennis. This has to be among the most beautiful subspecies that I’ve seen yet of what must be considered one of North America’s most attractive species of longhorned beetle. In contrast to the other “orange” subspecies, C. c. monoensis, which we had collected the previous day but that I did not even recognize as C. coralinus because of its color and very small size, I knew exactly what I was looking for on this day as we began to scan the gray rabbitbrush (Ericameria nauseosa) plants that stretched out across the Owens Valley sage grassland as far as the eye could see. At first we were worried that we might be a little late, as most of the plants appeared to be somewhat past peak bloom, but it wasn’t long before we found the first individual sitting atop a flower cluster, and then another, and another...

Males are solid, sublimely orange with strikingly contrasting black legs and antennae.

Crossidius c. caeruleipennis is immediately distinguishable from C. c. temprans (and most of the other C. coralinus ssp. that we collected on the trip further north in Nevada and east in Utah and Colorado) by its bright orange rather than dark red coloration. The subspecies is restricted to the Owens Valley of eastern California and greatly resembles another of the orange subspecies that we collected on the trip, C. c. monoensis. That subspecies is found just a short distance north in the Mono Basin, though at much higher elevations, and is easily distinguished from C. c. caeruleipennis by its smaller average size, by having the black markings of the elytra more expanded apically in females and at least present in males, and by the presence of black bands along the apical and basal margins of the pronotum (Linsley & Chemsak 1961).

Females are distinguished by the apical blue-black marking on the elytra and their shorter antennae.

As it turned out, the beetle was as abundant as any we had seen on the trip to that point. Not that it didn’t require some effort to collect them—they were still rather sparsely distributed among the plants and definitely showed preference for plants that were not as far past peak bloom. However, the habitat was extensive—we could have wandered freely for hours on end without looking at the same plant twice (although that did not stop me from re-checking a few plants that were in peak bloom and seemed to be especially favored). The males were simply gorgeous—a bright, creamy orange that sadly takes on a dull quality in preserved specimens and with long black legs and antennae. The females are no dogs either, less strikingly orange due to the blue-black apical markings on the elytra, but certainly more robust than the males in a subspecies that is already one of the larger of the species. Temperatures climbed rapidly at this relatively southern and lower elevation locality compared to most of the others that we visited during the trip, so the beetles became quite active very quickly after we began to see them. I had only a short window of time in which to attempt field photographs, and while I’m not completely satisfied with the ones that I show here, they were the best that I could manage and still get the blue sky background that I desire for “beetles on flowers” photographs.

Gray rabbitbrush dominates the Owens Valley sage grassland where C. coralinus caeruleipennis occurs.

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 2014

“Westerly from Westgard Pass is a view equaled in few parts of America. In the middle distance, a dozen miles away and nearly a mile below, lies the fertile Owens Valley, extending at right angles north and south over a hundred miles, and on the farther side, distant a score of miles, tower the snow-clad Sierras, with serrated crests and symmetric domes and peaks outlined against the sky at an approximate height of two and one-half miles vertical above the level of the ocean, and extending north and south far as the eye can see. The vision is rich reward for a journey of a thousand leagues.”—A. L. Westgard, March 1915

View to Westgard Pass from higher up in the White Mountains near Ancient Bristlecone Pine Forest.

After a morning spent searching for Crossidius coralinus caeruleipennis (perhaps the most sublimely beautiful of the subspecies) in the high desert sage of the wide open Owens Valley floor near Bishop, California, we made the short drive south to Big Pine, turned sharply left, and began the slow, twisting ascent through a narrow gap between the White Mountains to the north and the Inyo Mountains to the south. Eventually reaching an elevation of 7,313 ft,  Westgard Pass serves as access to Earth’s oldest living things! and, in doing so, provides some of the most striking scenery in the entire Basin and Range Province of eastern California.

Chrysothamnus viscidiflorus (small plants with yellow flowers) host Crossidius hirtipes nubilus adults.

Field mate Jeff Huether and I no doubt wanted to see the grotesquely beautiful trees growing in Ancient Bristlecone Pine Forest and were happy to enjoy the magnificent scenery along the way, but our trek to Westgard Pass had also a strictly entomological purpose—to search for Crossidius hirtipes nubilus, among the most uniquely colored and geographically restricted of the C. hirtipes subspecies. Approaching the summit, the narrow, rocky gorge opened up to a broad expanse of pinyon/juniper woodland, and nestled among the ubiquitous sage we found the plant we were looking for—yellow rabbitbrush (Chrysothamnus viscidiflorus) in full bloom.

Crossidius hirtipes nubilus (male) on flowers of Chrysothamnus viscidiflorus (field photo).

It took a while, however, before we found the beetles that we were looking for. Robust gray rabbitbrush (Ericameria nauseosa) plants in full bloom conspicuously dominated the roadsides and demanded our initial attentions, but our only reward was the widespread Crossidius ater. Not even a single Crossidius coralinus specimen could be claimed as consolation. Still, we knew the real quarry was further back from the roadsides, on the much smaller and less conspicuous yellow rabbitbrush that serves as an adult host for Crossidius hirtipes and most of its subspecies. Once we turned our attentions to these smaller plants we found the first adult fairly quickly, but precious few were seen considering the many plants that we examined until we finally zeroed in on one area just south of the summit where the beetles seemed to occur with slightly greater frequency. While not numerous, we eventually found enough beetles for us to declare, “Let’s go see the bristlecone pines!”

In addition to longer antennae, males are distinguished by less extensive clouding (studio photo).

This subspecies is among the most distinctive of all the C. hirtipes subspecies due to the combination of dark reddish-brown coloration and extreme, dark clouded area of the elytra (Linsley & Chemsak 1961). It most closely resembles C. h. rhodopus, which occurs further north in the Mono Basin, but that subspecies is not as dark and lacks the extensive clouding of black on the apical portions of the elytra.

Females have the markings greatly expanded to almost completely cover the elytra (studio photo).

The dark clouding actually represents an expansion of the dark stripe found along the suture of the elytra of many C. hirtipes subspecies, most of which exhibit sexual dimorphism in the degree to which this stripe is developed. In some subspecies the stripe is present in the females but absent in the males, while in others the stripe is present in both but more fully developed in the female. In C. h. nubilus the sutural stripe reaches an extreme state of development, covering much of the apical two-thirds of the elytra in the male and being so greatly expanded in females that almost the entire elytra are covered except for two small subbasal patches revealing the ground color of the elytra.

REFERENCES:

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 2014