{"id":97,"date":"2015-04-04T02:38:27","date_gmt":"2015-04-04T02:38:27","guid":{"rendered":"https:\/\/aphidtrek.org\/?page_id=97"},"modified":"2025-11-17T00:29:11","modified_gmt":"2025-11-17T00:29:11","slug":"pleotrichophorus","status":"publish","type":"page","link":"https:\/\/aphidtrek.org\/?page_id=97","title":{"rendered":"Pleotrichophorus"},"content":{"rendered":"\n

Pleotrichophorus<\/em> B\u00f6rner<\/strong><\/p>\n\n\n\n

This page updated: November 2025.<\/p>\n\n\n\n

This genus is one of my favorites. Many of its species are charismatic in some way, being excellently camouflaged, or being gaudy in color, or being especially fleet-of-foot. They are also terribly frustrating to photograph largely because of the latter trait. It seems like they, as with most aphids living on desert shrubs, are disturbed as soon as their host plant is jostled and especially once their leaf or sprig is clipped off.\u00a0 Once disturbed they stubbornly refuse to hold still for photos.\u00a0 There are many described species of Pleotrichophorus<\/em>, and it seems to me that most of the accepted species are valid and recognizable in the field and on slides. The genus lives mostly on Asteraceae, and mostly on shrubs and perennial herbs in xeric habitats such as sagebrush (Artemisia<\/em>) and rabbitbrush (Ericameria<\/em> and Chrysothamnus<\/em>).<\/p>\n\n\n

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\"Pleotrichophorus<\/a>
Pleotrichophorus<\/em> ex Achillea<\/em> from Hell’s Canyon, Idaho.<\/figcaption><\/figure>\n<\/div>\n\n\n

The revision of North American Pleotrichophorus<\/em> by Corpuz-Raros and Cook (1974) is really excellent in my opinion, especially considering neither author had done very much collecting in the field.  After all my years of collecting this genus, I still find most samples fit fairly well one of the species concepts laid out in their paper.  If I had infinite time and money to publish on aphids, I would love to do a complete revisit of their paper, pointing out all the ways they were right, and the few ways I think their work could be improved.<\/p>\n\n\n\n

One issue with the genus is that some pairs or groups of similar species are recognized from the same host in different geographic areas. Also, sometimes two species are recognized for very similar aphids that vary in one major character such as length of siphunculi or a particular ratio of body part lengths. Based on my extensive collecting, I think close examination will reveal some of these species names to be applied to regional or host-plant variants of more widely distributed and variable species. An example of this issue are the species found on Achillea<\/em> across North America (see P. patonkus<\/em> below).<\/p>\n\n\n\n

During fall of 2020 I made an effort to sort my material of several Pleotrichophous<\/em> species including P. brevinectarius, P. gnaphalodes, P. decampus, P. zoomontanus<\/em>, and P. quadritrichus<\/em>. Sorting was made easier by having accumulated much material from all over the western U.S. What I found was that my identifications were mixed, and some of these ‘species’ were mixtures of 2, 3, or even 4 species that are actually fairly easy to recognize with adequate experience and comparative material (which I now have). These changes in identification were reflected in my 2021 release of the slide collection database.<\/p>\n\n\n\n

In addition to the possibly erroneous splitting of geographically isolated populations of this genus into separate species, I consider another issue equally concerning: that some relatively distinctive ‘species’ that feed on several different plant species may be groups of similar-looking host-specific species. Examples of this phenomenon are what I had been calling P. brevinectarius<\/em> and P. quadritrichus<\/em>. There seem to be small but consistent differences in these ‘species’ based on Artemisia<\/em> species they developed upon.<\/p>\n\n\n\n

For several years I have been gathering samples of Pleotrichophorus<\/em> from a native weedy plant called Iva axillaris<\/em> (poverty weed). I have found this aphid in several western states. Since moving to Colorado I have it more or less in the front yard. When first found I ran it through the Corpuz-Raros and Cook key and it came out at P. parilis<\/em>. At the time I lacked samples of this species from its previously known host, Artemisia dracunculus<\/em>. Having found P. parilis<\/em> on the latter plant in recent years, I decided in January 2024 to examine whether the form from I. axillaris<\/em> can be consistently separated from P. parilis<\/em>. The answer was, to my surprise, an easy “yes.” So, at some point I have at least one new species of Pleotrichophorus<\/em> to describe!<\/p>\n\n\n\n

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According to what I can glean from Aphid Species File,<\/a> there are 60 recognized species of Pleotrichophorus<\/em> worldwide and about 44 of those are of North American origin. Because I have collected and studied this genus so much over the years, I thought I’d annotate everything in my collection much as I did for Illinoia<\/a><\/em> and Macrosiphum<\/a><\/em>. So below I will list and briefly discuss all 33 species I have identified in my collection, then all the recognized North American species I have not yet identified<\/a>, then all my <\/span>putative undescribed species<\/a>.<\/p>\n\n\n\n

Species covered below (click on the name to jump to that species):<\/h2>\n\n\n\n