{"id":21,"date":"2015-04-02T22:19:47","date_gmt":"2015-04-02T22:19:47","guid":{"rendered":"https:\/\/aphidtrek.org\/?page_id=21"},"modified":"2025-02-15T19:36:50","modified_gmt":"2025-02-15T19:36:50","slug":"macrosiphum","status":"publish","type":"page","link":"https:\/\/aphidtrek.org\/?page_id=21","title":{"rendered":"Macrosiphum"},"content":{"rendered":"\n

Macrosiphum<\/em> Passerini<\/strong><\/h2>\n\n\n\n

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

Macrosiphum<\/em> is my favorite aphid group, getting my start on its diversity and field biology way back in undergraduate years with exploration of the first host alternation of a fern-feeding species. In those days Sitobion<\/em> was still used for some of the species now considered Macrosiphum<\/em>; this brings up the point that the name Macrosiphum<\/em> is now used for what is likely a polyphyletic assemblage of species.  Some day it might turn out to be better thought of as 2, 3, or more genera.<\/p>\n\n\n

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\"Macrosiphum<\/a>
Macrosiphum rhamni oviparous female.<\/figcaption><\/figure>\n<\/div>\n\n\n

Jensen, A.S.<\/strong>, J.D. Lattin and G.L. Reed. 1993. Host plant alternation in two fern-feeding Sitobion<\/em> Mordvilko. in: Critical Issues in Aphid Biology: Proceedings of the 4th International Symposium on Aphids<\/em>. P. Kindlmann and A.F.G. Dixon, eds. 142 pp.<\/p>\n\n\n\n

Since then I finished a Ph.D. studying this group, and published 20 new species (so far, more to come).  My impression of this group is that there has been recent and rapid diversification, especially so in western North America.  There are many tightly host-specific species that are morphologically similar.  But you should be able to see from the coverage of species here on AphidTrek that Macrosiphum<\/em> species come in many beautiful colors and live in some fabulous ecosystems.<\/p>\n\n\n\n

Jensen, A.S.<\/strong> 2022. A new species of Macrosiphum<\/em> (Hemiptera: Aphididae) living on Silene<\/em> (Caryophyllaceae). Zootaxa<\/em>, 5183 (1): 75\u201389.<\/p>\n\n\n\n

Jensen, A.S.<\/strong> and J. Rorabaugh. 2020. New Macrosiphum<\/em> Passerini (Hemiptera: Aphididae) Information from Western North America Including One New Species and One New Synonymy. Proceedings of the Entomological Society of Washington<\/em> 122: 81-103.<\/p>\n\n\n\n

Jensen, A.S.<\/strong>, R. Pe\u00f1a-Martinez, A.L. Mu\u00f1oz-Viveros, and J. Rorabaugh. 2019. A New Species of Macrosiphum<\/em> Passerini (Hemiptera: Aphididae) from Mexico on the Introduced Plant Pittosporum undulatum<\/em>. Proceedings of the Entomological Society of Washington<\/em> 121: 39-53.<\/p>\n\n\n\n

Jensen, A.S.<\/strong> 2017. Two New Species of Macrosiphum<\/em> Passerini (Hemiptera: Aphididae) from Dry Forests of Western United States. Proceedings of the Entomological Society of Washington<\/em> 119: 580-600.<\/p>\n\n\n\n

Jensen, A.S.<\/strong> 2015. Two New Species of Macrosiphum<\/em> Passerini (Hemiptera: Aphididae) From Western North America. Proceedings of the Entomological Society of Washington<\/em> 117: 481-494.<\/p>\n\n\n\n

Jensen, A.S.<\/strong> 2012. Macrosiphum<\/em> (Hemiptera: Aphididae) Update: One New Species, One Synonymy, and Life Cycle Notes. Proceedings of the Entomological Society of Washington<\/em> 114: 205-216.<\/p>\n\n\n\n

Jensen, A.S. <\/strong>and C.K. Chan. 2009. Macrosiphum<\/em> living on Fumariaceae in northwestern North America, including one new species (Hemiptera: Aphididae). Proceedings of the Entomological Society of Washington<\/em> 111: 617\u2011626.<\/p>\n\n\n\n

Jensen, A.S.<\/strong> and J. Holman. 2000. Macrosiphum<\/em> on ferns: taxonomy, biology and evolution, including the description of three new species (Hemiptera: Aphididae). Systematic Entomology<\/em> 25: 339-372.<\/p>\n\n\n\n

Jensen, A.S.<\/strong> 2000. Eight new species of Macrosiphum<\/em> Passerini from western North America, with notes on four other poorly known species (Hemiptera: Aphididae). Proceedings of the Entomological Society of Washington<\/em> 102: 427-472.<\/p>\n\n\n\n

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

In January of 2025 I was considering what additions and amendments to do next on aphidtrek.org. At the time I had already covered 39 species in the page below and I thought it would be interesting to add all the other species in my collection, whether I have photos or not, to add some taxonomic comments here and there, and to think about what else might be useful or interesting to extract from my brain and put “on paper.” According Aphid Species File<\/a> there are 162 valid, recognized species of Macrosiphum<\/em>. Let’s see how many of those I have in my little personal collection (click on the name to jump to that species)!<\/p>\n\n\n\n

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  1. Macrosiphum adianti (Oestlund)<\/a><\/em><\/li>\n\n\n\n
  2. Macrosiphum aetheocornum<\/em> Smith & Knowlton<\/a><\/li>\n\n\n\n
  3. Macrosiphum agrimoniellum<\/em> (Cockerell)<\/a><\/li>\n\n\n\n
  4. Macrosiphum albifrons<\/em> Essig<\/a><\/li>\n\n\n\n
  5. Macrosiphum badium<\/em> Jensen<\/a><\/li>\n\n\n\n
  6. Macrosiphum californicum<\/em> (Clarke)<\/a><\/li>\n\n\n\n
  7. Macrosiphum cholodkovskyi<\/em> (Mordvilko)<\/a><\/li>\n\n\n\n
  8. Macrosiphum claytoniae<\/em> Jensen<\/a><\/li>\n\n\n\n
  9. Macrosiphum clum<\/em> Jensen<\/a><\/li>\n\n\n\n
  10. Macrosiphum clydesmithi<\/em> Robinson<\/a><\/li>\n\n\n\n
  11. Macrosiphum corydalis<\/em> (Oestlund)<\/a><\/li>\n\n\n\n
  12. Macrosiphum creelii<\/em> (Davis)<\/a><\/li>\n\n\n\n
  13. Macrosiphum cyatheae<\/em> (Holman)<\/a><\/li>\n\n\n\n
  14. Macrosiphum daphnidis<\/em> B\u00f6rner<\/a><\/li>\n\n\n\n
  15. Macrosiphum dewsler<\/em> Jensen<\/a><\/li>\n\n\n\n
  16. Macrosiphum dicentrae<\/em> Jensen & Chan<\/a><\/li>\n\n\n\n
  17. Macrosiphum diervillae<\/em> Patch<\/a><\/li>\n\n\n\n
  18. Macrosiphum dryopteridis<\/em> (Holman)<\/a><\/li>\n\n\n\n
  19. Macrosiphum equiseti<\/em> (Holman)<\/a><\/li>\n\n\n\n
  20. Macrosiphum euphorbiae<\/em> (Thomas)<\/a><\/li>\n\n\n\n
  21. Macrosiphum euphorbiellum<\/em> Theobald<\/a><\/li>\n\n\n\n
  22. Macrosiphum funestum<\/em> (Macchiati)<\/a><\/li>\n\n\n\n
  23. Macrosiphum garyreed<\/em> Jensen<\/a><\/li>\n\n\n\n
  24. Macrosiphum gaurae<\/em> (Williams)<\/a><\/li>\n\n\n\n
  25. Macrosiphum gei<\/em> (Koch)<\/a><\/li>\n\n\n\n
  26. Macrosiphum ginajo<\/em> Jensen<\/a><\/li>\n\n\n\n
  27. Macrosiphum glawatz<\/em> Jensen<\/a><\/li>\n\n\n\n
  28. Macrosiphum hartigi<\/em> Hille Ris Lambers<\/a><\/li>\n\n\n\n
  29. Macrosiphum hellebori<\/em> Theobald and Walton<\/a><\/li>\n\n\n\n
  30. Macrosiphum holodisci<\/em> Jensen<\/a><\/li>\n\n\n\n
  31. Macrosiphum impatientis<\/em> (Williams)<\/a><\/li>\n\n\n\n
  32. Macrosiphum knautiae<\/em> Holman<\/a><\/li>\n\n\n\n
  33. Macrosiphum lambi<\/em> Robinson<\/a><\/li>\n\n\n\n
  34. Macrosiphum longirostratum<\/em> Jensen & Holman<\/a><\/li>\n\n\n\n
  35. Macrosiphum manitobense<\/em> Robinson<\/a><\/li>\n\n\n\n
  36. Macrosiphum melampyri<\/em> Mordvilko<\/a><\/li>\n\n\n\n
  37. Macrosiphum mentzeliae<\/em> Wilson<\/a><\/li>\n\n\n\n
  38. Macrosiphum mertensiae<\/em> Gillette & Palmer<\/a><\/li>\n\n\n\n
  39. Macrosiphum miho<\/em> Jensen & Holman<\/a><\/li>\n\n\n\n
  40. Macrosiphum niwanistum<\/em> (Hottes)<\/a><\/li>\n\n\n\n
  41. Macrosiphum occidentale<\/em> (Essig)<\/a><\/li>\n\n\n\n
  42. Macrosiphum olmsteadi<\/em> Robinson<\/a><\/li>\n\n\n\n
  43. Macrosiphum opportunisticum<\/em> Jensen<\/a><\/li>\n\n\n\n
  44. Macrosiphum oredonense <\/em>Remaudi\u00e8re<\/a><\/li>\n\n\n\n
  45. Macrosiphum oregonense<\/em> Jensen<\/a><\/li>\n\n\n\n
  46. Macrosiphum osmaroniae<\/em> (Wilson)<\/a><\/li>\n\n\n\n
  47. Macrosiphum pallens<\/em> Hottes & Frison<\/a><\/li>\n\n\n\n
  48. Macrosiphum pallidum<\/em> Patch<\/a><\/li>\n\n\n\n
  49. Macrosiphum parvifolii<\/em> Richards<\/a><\/li>\n\n\n\n
  50. Macrosiphum potentillae<\/em> (Oestlund)<\/a><\/li>\n\n\n\n
  51. Macrosiphum prenanthidis <\/em>B\u00f6rner<\/a><\/li>\n\n\n\n
  52. Macrosiphum (Neocorylobium) pseudocoryli<\/em> Patch<\/a><\/li>\n\n\n\n
  53. Macrosiphum ptericolens<\/em> Patch<\/a><\/li>\n\n\n\n
  54. Macrosiphum pteridis<\/em> (Wilson)<\/a><\/li>\n\n\n\n
  55. Macrosiphum rebecae<\/em> Jensen & Holman<\/a><\/li>\n\n\n\n
  56. Macrosiphum rhamni <\/em>(Clarke)<\/a><\/li>\n\n\n\n
  57. Macrosiphum rosae<\/em> (L.)<\/a><\/li>\n\n\n\n
  58. Macrosiphum rudbeckiarum<\/em> (Cockerell)<\/a><\/li>\n\n\n\n
  59. Macrosiphum salviae <\/em>Bartholomew<\/a><\/li>\n\n\n\n
  60. Macrosiphum schimmelum<\/em> Jensen<\/a><\/li>\n\n\n\n
  61. Macrosiphum stanleyi<\/em> (Wilson)<\/a><\/li>\n\n\n\n
  62. Macrosiphum stellariae<\/em> Theobald<\/a><\/li>\n\n\n\n
  63. Macrosiphum tenuicauda<\/em> Bartholomew<\/a><\/li>\n\n\n\n
  64. Macrosiphum thermopsaphis<\/em> Knowlton<\/a><\/li>\n\n\n\n
  65. Macrosiphum tolmiea<\/em> (Essig)<\/a><\/li>\n\n\n\n
  66. Macrosiphum tonantzin<\/em> Pe\u00f1a-Martinez, Mu\u00f1oz-Viveros, & Jensen<\/a><\/li>\n\n\n\n
  67. Macrosiphum tuberculaceps<\/em> (Essig)<\/a><\/li>\n\n\n\n
  68. Macrosiphum valerianae<\/em> (Clarke)<\/a><\/li>\n\n\n\n
  69. Macrosiphum vancouveriae<\/em> Jensen<\/a><\/li>\n\n\n\n
  70. Macrosiphum venaefuscae <\/em>Davis<\/a><\/li>\n\n\n\n
  71. Macrosiphum violae<\/em> Jensen<\/a><\/li>\n\n\n\n
  72. Macrosiphum walkeri <\/em>Robinson<\/a><\/li>\n\n\n\n
  73. Macrosiphum willamettense<\/em> Jensen<\/a><\/li>\n\n\n\n
  74. Macrosiphum wilsoni<\/em> Jensen<\/a><\/li>\n\n\n\n
  75. Macrosiphum woodsiae<\/em> Robinson<\/a><\/li>\n\n\n\n
  76. Macrosiphum zionense<\/em> Knowlton<\/a><\/li>\n<\/ol>\n\n\n\n

    Well, that was fun! Seventy six of 162 species isn’t bad for a self-funded hobbyist’s collection. I thought I’d continue this listing process with a few comments on the North American ‘species’ I have not yet found. At the very bottom of this page I cover the forms I know of that are probably undescribed species. Click here to jump to that list<\/a>.<\/p>\n\n\n\n

    Macrosiphum amelanchiericolens <\/em><\/strong>Patch
    This name was created by Patch in 1919 for a form she found on Amelanchier spicata<\/em> in Maine. Her description was based on one, possibly more, alate vivipara. About the only distinctive features she mentions in the very brief description is that the cauda is “comparatively short and rugged” and that the ANT III has “about 40 sensoria.” These facts suggest to me that she was indeed looking at something other than M. euphorbiae<\/em>, but it is hard to guess what it might be. MacGillivray (1968) reported that Patch had discarded many of her slides that she thought worthless, including the type of this species. Therefore, we are left without an ability to recognize this species and nothing like it has apparently been collected on Amelanchier<\/em> since 1914.<\/p>\n\n\n\n

    Macrosiphum audeni <\/em><\/strong>Macdougall
    This form was described in 1926 based on material on the aquatic plant Nuphar polysepala<\/em> (a.k.a., lily pad) from two sites in British Columbia, Canada. The description is wholly inadequate to recognize the species. I have searched Nuphar<\/em> every chance I’ve had for decades without finding any aphids other than Rhopalosiphum nymphaeae<\/em>. It may be a northern species, and it may require a canoe or a swimming suit to find. I made the following note to myself several years ago: “Extensive interaction with the CNC and Cho-Kai Chan (retired, of UBC, Vancouver) about the whereabouts of MacDougall types throughout 2008 and 2009 indicates that perhaps all her Macrosiphum<\/em> types are lost.” This is a shame, if true.<\/p>\n\n\n\n

    Macrosiphum bisensoriatum <\/em><\/strong>Macdougall
    Another poorly described species from 1926, this species is also not recognizable based on the description, and with the likely loss of MacDougall’s types, we may never know what this species is. I have collected avidly on all Ribes<\/em> species for decades without finding any Macrosiphum<\/em> specimens.<\/p>\n\n\n\n

    Macrosiphum (Neocorylobium) carpinicolens<\/em><\/strong> Patch
    Here is a species, unlike the previous three, that is fairly well-known and moderately easy to find on its host Carpinus<\/em> (hornbeam) in eastern North America. I was lucky enough to collect it several times while a postdoc at the U.S. national insect collection in Maryland. Alas, I did not grab any for my personal collection before leaving Maryland in 1999.<\/p>\n\n\n\n

    Macrosiphum constrictum <\/em><\/strong>Patch
    This is a species I pondered quite a lot when in graduate school. It was collected on St Paul Island in the Bering Sea in 1913, using a species of Pedicularis<\/em> as host. It has reduced reticulation on the siphunculi compared to many Macrosiphum<\/em>, and is probably a good species. Alas, many years of collecting on Pedicularis <\/em>everywhere I go has not turned up this aphid, and I have unfortunately never gotten the chance to go collecting in the Bering Sea.<\/p>\n\n\n\n

    Macrosiphum corallorhizae <\/em><\/strong>Cockerell
    This is a name coined by Cockerell in 1903 for Macrosiphum<\/em> aphids found feeding on the myco-heterotrophic orchid Corallorhiza maculata<\/em> in New Mexico. As typical in those days, the description is inadequate for species recognition. I have seen two samples of Macrosiphum<\/em> aphids on Corallorhiza<\/em> over the years, and to me they look like large M. euphorbiae<\/em>. Further, I think it highly unlikely that there would be a host-specific aphid on an ephemeral myco-heterotrophic plant. Finding thriving populations of M. euphorbiae<\/em> on such a plant, however, would not surprise me at all.<\/p>\n\n\n\n

    Macrosiphum (Neocorylobium) coryli<\/em><\/strong> Davis
    This species is known to feed on Corylus<\/em> across much of northern North America. Despite collecting on Corylus<\/em> anywhere I find it, I have never found this species. Like a few other species, I think I might have more luck finding it if I spent a good chunk of collecting time in Canada or across the U.S. near the Canadian border; I’ve noticed over the years that aphids and plants seem to recognize the international boundary, becoming noticeably different almost immediately after crossing the border.<\/p>\n\n\n\n

    Macrosiphum echinocysti <\/em><\/strong>Bartholomew
    This form was described in 1932 based on a single very large sample collected on Echinocystis lobata<\/em> (a.k.a., wild cucumber) in San Francisco, California. The description and figures are inadequate to recognize this form, and it has apparently not been collected since the description. When I visited the bay area in the 2000s I saw this plant growing in yards and along streets in the Berkeley area, and could not find any aphids. Bartholomew similarly noted that after that first collection he was unable to find this aphid in subsequent years. I suspect his form was an unusual host and appearance of     M. euphorbiae<\/a><\/em>.<\/p>\n\n\n\n

    Macrosiphum floridae <\/em><\/strong>(Ashmead)
    This name was coined in 1882 for some aphids found in Florida feeding on Rosa<\/em>. Apparently the types are either lost or were never designated, and the description is very poor by modern standards. Despite the intense insect monitoring characteristic of the Florida state government, no unusual rose-feeding Macrosiphum<\/em> species has ever since been collected there. I suspect this aphid may have been a     Wahlgreniella<\/a><\/em> or perhaps a Rhodobium<\/em>. Resolving the status of this name will probably require consultation of the dreaded International Code of Zoological Nomenclature to figure what can be done with what is probably a name without a species.<\/p>\n\n\n\n

    Macrosiphum fuscicornis <\/em><\/strong>Macdougall
    From her description I am leaning toward this species being valid. The apparent loss of all Macdougall Macrosiphum<\/em> types (see above) is of course not helpful. The fact it was recorded as a dark green color with relatively dark appendages would seem to rule out two common species,     M. valerianae<\/em><\/a> and M. euphorbiae<\/em><\/a>. Macdougall mentions that alatae are uncommon, appearing in June and August, which is consistent with a heteroecious species. So, might there be a heteroecious species up in Canada that fits what Macdougall saw 100 years ago?<\/p>\n\n\n\n

    Macrosiphum geranii <\/em><\/strong>(Oestlund)
    Despite many years of study and collecting I am still not sure what this name applies to. I see quite a diversity of Macrosiphum<\/em> living on Geranium<\/em> in North America. In my own collection I have samples sorted into 4 groups: those easily identified as     M. aetheocornum<\/em><\/a>, a group of specimens that look like M. euphorbiae<\/a><\/em> that are trying to look just a little wrong, some that look like M. aetheocornum<\/em> with relatively sparse setae, and a fourth with long thin siphunculi, a fat cauda, and abundant spinules ventrally on the head. I suspect that Oestlund’s species is not among these, but I am not sure I can recognize what he had if I see it. Many years ago when studying at the U.S. national aphid collection (USNM) I wrote, “The material in the USNM is obviously composed of two species. There are 25 slides of a species from Manitoba and Wisconsin that has a smooth venter of the head, but a very spinulose cornicle. This species also tends to have more setae on the URS. The other species is material from PA, MD, IL, and it has more normal looking cornicles, but densely spinulose ventral surface of head. This one also has URS with 6 accessory setae. One specimen from Manitoba appears to be M. euphorbiae<\/em>, while the specimen from Sask. is a nymph.” So it seems likely that there are 2 to 4 species currently being confused under this name. The identity of this species might best be resolved by collecting on wild Geranium<\/em> in and near Minneapolis, which is where Oestlund was working and collecting in the 1880s.<\/p>\n\n\n\n

    Macrosiphum hamiltoni <\/em><\/strong>Robinson
    A.G. Robinson described this species from Humulus<\/em> (cultivated hops) in 1968 (I was fortunate enough to learn much from Grant during our correspondence via paper letter and email during the 1990s). It is surprising to find a new Macrosiphum<\/em> species living on a cultivated non-native crop plant. When studying material in the USNM I wrote, “I think Eastop is wrong in calling this species the same as the one on Cornus<\/em>. This is closer to Illinoia<\/em> than that Macrosiphum<\/em> species, based on several paratypes and other material. No alates in the collection. The head is pale, the antennae with banded joints. Is this one related to M. olmsteadi<\/em>?” So anyhow, I think this is a good species with a very mysterious biology deserving further study in the Winnipeg area (Manitoba, Canada).<\/p>\n\n\n\n

    Macrosiphum jasmini <\/em><\/strong>(Clarke)
    The aphids Clarke based his description on were collected in Berkeley, California around 1902 living on Jasminum<\/em>, a non-native ornamental plant. His description is very brief and inadequate. While visiting the University of California insect collection in Berkeley some years ago i wrote, “Types are probably lost. The slide at Berkeley labeled as type is obviously a mis-labeled sample from another collection in Clarke (1903); the specimens were Hyperomyzus<\/em>. Hence, types must actually be lost.” During this trip I spent an afternoon walking all over Berkeley and the university campus looking for this and a few other species originally collected there. Although I did find some Jasminum<\/em>, I found no aphids feeding on it. I suspect the aphids Clarke studied were     M. euphorbiae<\/em><\/a>.<\/p>\n\n\n\n

    Macrosiphum<\/em> lilii<\/em> <\/strong>(Monell)
    This species has been collected in several states of eastern U.S. I had the chance to look at this material when studying at the USNM. I wrote about it, “This species has dark tips of femora, bases and apices of tibiae, and antennae usually dark, with middle part of III normally lighter. Based on many specimens from the eastern U.S. This is possibly an Asian species, and relationship to Japanese and Chinese species should be explored. May also be native to eastern North America?” While living in Maryland for 3 years I avidly searched for this species without success.<\/p>\n\n\n\n

    Macrosiphum orthocarpus <\/em><\/strong>Davidson
    This form was found living on Castilleja exserta<\/em> (recorded as Orthocarpus<\/em>, owl clover) near Stanford University in California during the few years before 1909. This plant is a hemiparastic annual, so I strenuously doubt that an aphid would be monoecious on it. Davidson’s description is very brief. Considering these facts plus the commonness of M. euphorbiae<\/em> on Castelleja<\/em>, and my examination of the type material in the USNM (2 alate viviparae) I suspect that what Davidson had was M. euphorbiae<\/em>.<\/p>\n\n\n\n

    Macrosiphum pechumani <\/em><\/strong>MacGillivray
    This distinctive species lives on large lily-like plants such as Maianthemum racemosum<\/em> in eastern North America. I was not able to find it in my handful of collecting trips in the region, but I have studied specimens in the USNM and it is clearly distinct and interesting.<\/p>\n\n\n\n

    Macrosiphum pyrifoliae<\/em><\/strong> Macdougall
    Another of Macdougall’s species the types of which are apparently lost, this one was described from Sorbus sitchensis<\/em> (then recorded as Pyrus occidentalis<\/em>). Other specimens have apparently been collected near the type locality, and were said to be very similar to M. euphorbiae<\/em>. Whether this is a good species cannot be known for sure at present. Further study in the field in British Columbia would probably help (despite decades of looking for aphids on Sorbus<\/em>, I have never found a Macrosiphum<\/em>).<\/p>\n\n\n\n

    Macrosiphum raysmithi <\/em><\/strong>Hille Ris Lambers
    This species has, like several others in this list, received a lot of collecting effort over the past 3 decades, so far without luck. Originally collected on Lonicera involucrata var. ledebourii<\/em> in Berkeley, California, it is distinctive among, but clearly part of, the group of Macrosiphum<\/em> species that live on Caprifoliaceae around the Northern Hemisphere. During my trip to Berkeley in 2014 I explored every nook and cranny of the university campus looking for Lonicera<\/em> shrubs that might host this species. I think I ended up finding a plant or two, but not this aphid.<\/p>\n\n\n\n

    Macrosiphum tiliae<\/em><\/strong> (Monell)
    This is another story of a failed collecting expedition. I have been intrigued by this distinctive tree-feeding aphid for decades, and in 2017 we planned a trip to the Midwest (especially Wisconsin and Minnesota) in May to visit family and collect aphids. The key collecting targets of this trip were a few Macrosiphum<\/em> species including M. tiliae<\/em>. Alas, that particular year featured a late spring, so we were 2 or 3 weeks early to see spring generations of tree-feeding aphids and I was not able to find M. tiliae<\/em>.<\/p>\n\n\n\n

    Macrosiphum timpanogos <\/em><\/strong>Knowlton
    This name was coined by George Knowlton in 1942 based on a single sample of an unreported number of apterous viviparae collected on Mt. Timpanogos in Utah on 23 July 1940. The host plant was not known, but Knowlton wrote, “Host? (probably from a lupine of some kind).” He may have deduced this because the aphid is very similar to the common lupine-feeding aphid     Macrosiphum albifrons<\/em><\/a>. I saw the type slide in the USNM and wrote about it, “This appears to be another synonym of M. albifrons<\/em>, or at least closely related. The type slide is two specimens that are badly over-cleared.” As noted far below, I have concluded that the species Macrosiphum thermopsaphis<\/a><\/em> may be valid despite decades of it being treated as a synonym of Macrosiphum zionense<\/a><\/em>, and in the same way it is possible that Knowlton’s material represents a separate lupine-feeding species. Probably the only way to learn more is extensive field work in the area of Mt. Timpanogos. I have collected typical-looking M. albifrons<\/em> from that part of Utah, but have never seen anything that I would consider unusual or would fit what Knowlton wrote about M. timpanogos<\/em>.<\/p>\n\n\n\n

    Macrosiphum (Neocorylobium) vandenboschi<\/em> <\/strong>(Hille Ris Lambers)
    This is another apparently distinctive Corylus<\/em>-feeding species from California. Hille Ris Lambers described it based on 2 apterous viviparae collected in Tulare County, California on 13 July 1961. Despite 3 decades of collecting on Corylus<\/em> everywhere I see it, I have not found this species. That said, I have not collected in California anywhere near enough to understand its aphid diversity.<\/p>\n\n\n\n

    Macrosiphum verbenae <\/em><\/strong>(Thomas)
    This name was coined in 1878 for some aphids collected in Illinois on Verbena<\/em>. Based on specimens I have seen and some collecting I have done on Verbena<\/em> over the years, I am almost certain this is M. euphorbiae<\/em> showing some environment-induced variation in color and general appearance, a common and easily documented phenomenon in     M. euphorbiae<\/a><\/em>.<\/p>\n\n\n\n

    OK! That was fun too! In summary, my view is that there are still 16 species I should try to find in the U.S.A. and Canada, and that 7 of the remaining names just listed are probably not valid species, being synonyms of M. euphorbiae, M. albifrons<\/em>, or perhaps other genera in the case of M. floridae<\/em>. Cleaning up these 7 names should perhaps be a priority if I ever get around to publishing a complete work on Macrosiphum<\/em> of U.S.A. and Canada (there is no way I could cover North America as a whole without many years of access to and collecting in Mexico, the likelihood of which is approximately zero).<\/p>\n\n\n\n

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    Macrosiphum adianti<\/em> (Oestlund)<\/strong><\/p>\n\n\n\n

    In the late 1990s I had the great honor to collaborate with the late Jaroslav Holman on a paper that covered the fern-feeding Macrosiphum<\/em> of the world. He had material from Europe, Mexico, and the Caribbean, and I had material from the U.S.A. and Canada. This collaboration was carried out entirely via email and old-fashioned paper mail, sending specimens and slides through the mail. Jaroslav was generous and a great collaborator. Our paper was published in 2000, as shown in the list above. In it we covered the details about Macrosiphum adianti<\/em>, including a clarification of what this species was. We wrote about it:<\/p>\n\n\n\n

    “Biology and distribution. Macrosiphum adianti<\/em> is monoecious on Adiantum pedatum<\/em> L., with apterous males. Reproduction continues throughout the summer, but adults that develop in midsummer can be as little as one mm long. The aphid is rather rare, infesting only a small percentage of A. pedatum <\/em>plants in any given part of its range. It has so far been found in British Columbia, Oregon, California and Minnesota. There is extensive new material in the Oregon State University aphid collection. One parasitoid, Toxares deltiger<\/em> (Haliday) (Braconidae: Aphidiinae) was reared from this species in Oregon.<\/p>\n\n\n\n

    Systematic position. Macrosiphum adianti<\/em> can be recognized by its small size (usually about 2.0 mm), peculiar, short siphunculi with little or no reticulation (Fig. 3D) in apterous viviparae, low antennal tubercles (Fig. 3E,F), metatarsal II longer than u.r.s., and abdomen with patches or bands of pale sclerotization. It is so far the only species of Macrosiphum <\/em>collected on A. pedatum<\/em> in North America. The only other aphid known from this plant in North America is Papulaphis sleesmani<\/em>. Macrosiphum adianti<\/em> and P. sleesmani<\/em> differ primarily in the tuberculate, apically placed rhinaria on antennal segments III and IV for which Papulaphis<\/em> Robinson was named. Macrosiphum miho <\/em>is a similar species; the differences between the two are discussed under M. miho<\/em>.<\/p>\n\n\n\n

    Taxonomic notes.<\/em> Oestlund (1886) described this species in the genus Siphonophora<\/em> (= Macrosiphum<\/em>) from Hennepin and Ramsey County, Minnesota, feeding on A. pedatum<\/em>. This was the first species of fern-feeding Macrosiphum<\/em> described from North America. Ever since its original description, there has been much confusion about the identity of this species. Oestlund\u2019s description was short and, by modern standards, of little value in recognizing the species. Robinson (1966) reported that the types for this species could not be found in the Oestlund collection. He consequently based his concept of the species on material collected in Illinois on Aspidium.<\/em> We borrowed the slides used by Robinson to construct his concept of the species, and found that the specimens disagreed with Oestlund\u2019s description by possessing siphunculi and appendages that were much too long. Coincidentally we discovered a small yellowish Macrosiphum<\/em> on A. pedatum<\/em> in Oregon. Following a search in the University of Minnesota aphid collection (where the Oestlund collection is housed), P. Clausen found material of the same species, these collected by Oestlund on Vancouver Island, British Columbia in 1907. These specimens agree very well with the measurements provided by Oestlund (1886). Therefore, these specimens are here assigned to the name M. adianti<\/em>. The material used by Robinson from Illinois is described below as a new species, M. miho<\/em> sp.n. The location of the types of M. adianti<\/em> is still unknown.”<\/p>\n\n\n\n

    Since that time I have collected this species once in Washington.<\/p>\n\n\n\n

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    Macrosiphum aetheocornum <\/em>Smith & Knowlton<\/strong><\/p>\n\n\n\n

    For some years this species was a major collecting goal of mine.  I collected on geraniums of all kinds for many years before finding this aphid for the first time in 2010 in New Mexico.  Since then, I’ve found it many additional times, including fundatrices and sexuales, proving monoecy.  I find it on what I call Geranium richardsonii<\/em>, a plant that seems to have a wide variation in habitat preference and is irritatingly similar to G. viscosissimum<\/em> where their ranges overlap.  <\/p>\n\n\n\n

    In 2022 I published some information on this species as part of my work on M. ginajo<\/em><\/a>. I wrote: “Biology and Distribution<\/strong>. Macrosiphum aetheocornum<\/em> feeds on native Geranium<\/em> species, the species recorded
    by this author have been Geranium richardsonii<\/em> Fisch & Trautv. and Geranium viscosissimum<\/em> F. & M. Some collections listed above were recorded as Geranium<\/em> due to the author\u2019s limited plant taxonomy skills, but some of these were almost certainly species other than G. richardsonii<\/em> and G. viscosissimum<\/em>. In plants that are partially sticky\u2013glandular, post\u2013bloom, or that have the common intermediate pink flower color, the author struggles to confidently distinguish between the latter two species of Geranium<\/em>, so not all species identifications can be relied upon.<\/p>\n\n\n\n

    “Macrosiphum aetheocornum<\/em> has a full\u2013season life cycle with sexuales in September. This differs from another common aphid that frequently occurs on the same host plants, Nasonovia (Capitosiphon) crenicorna <\/em>Smith and Knowlton. The latter species has an abbreviated life cycle with sexuales in July and early August. The author has studied an unidentified species of Amphorophora<\/em> that also has an abbreviated life cycle on especially glandular\u2013sticky populations of G. viscosissimum<\/em>; this aphid may be Amphorophora coloutensis<\/em> Smith & Knowlton, which has a similarly abbreviated life cycle, but available identification keys and references are inadequate for species identification. These aphids with abbreviated life cycles often occupy stands of Geranium<\/em> in dryer habitats that dry out and enter dormancy during summer. Macrosiphum aetheocornum<\/em>, on the other hand, with its full\u2013season life cycle occupies plant stands in habitats that support vegetative growth all summer and into autumn. Typical habitats
    for M. aetheocornum<\/em> are forested riparian zones and the understory of pine forests, but it can also be found on hot and dry slopes with spring\u2013fed wet soils (such as the slopes above Lake Abert in Lake County, Oregon). The author has collected M. aetheocornum<\/em> in Oregon, California, Montana, Idaho, Utah, New Mexico, and Colorado. It almost certainly occurs in neighboring states such as Washington, Nevada, Arizona, and Wyoming.”<\/p>\n\n\n

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    \"Macrosiphum<\/a>
    Macrosiphum aetheocornum from central Oregon in June.<\/figcaption><\/figure>\n<\/div>\n\n\n

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    Macrosiphum agrimoniellum<\/em> (Cockerell)<\/strong><\/p>\n\n\n\n

    This species was described by T.D.A. Cockerell in 1903 while he was living in East Las Vegas, New Mexico. I’ve been through the Las Vegas area a few times, and am fascinated to think what it would have looked like 120 years ago (it is nothing like Las Vegas, Nevada, in case you were wondering) and what the heck an entomologist was doing in such a tiny town. A quick look at Wikipedia shows that he was there teaching at what was then called the New Mexico Normal School, now New Mexico Highlands University. <\/p>\n\n\n\n

    His description was based on a single sample collected in Beulah, New Mexico on 27 July 1902 by T.D.A. and W.P. Cockerell (his wife). Interestingly, a search on Google Maps turns up no towns or places called Beulah in New Mexico. A couple web pages mention that Beulah is now a ghost town and is in San Miguel County, the same county as Las Vegas. Cockerell’s description was based on one or more alatae viviparae. He wrote:<\/p>\n\n\n\n

    “Winged female (full of young) — Large, light apple green (orange-ferruginous mounted in balsam), without markings; eyes black; femora with basal two-thirds light green, distal third black, or sometimes less (about 90 \u03bc); distal 90 \u03bc of tibiae, and all of tarsi, black; nectaries suffused with blackish; antennae dusky, joint 3 black except the basal 30 \u03bc; third antennal joint with very numerous (about 32) protuberant sensoria, about equally distributed on the proximal and distal halves; cauda tapering, with a blunt tip, sides with bristles set on little prominences; no capitate hairs anywhere.<\/em>
    Length of body about 3 mm, wings about 3 \u00bd mm; other measurements in \u03bc: — Antennal joints: (1.) 120, (2.) 110, (3.) 1100, (4.) 900, (5.) 730, (6a) 160, (6b.) 1230. Cauda about 450; nectaries 1000, with imbricated surface; beak 700 to 750; anterior femur 1000; marginal cell with substigmatic portion 380, and poststigmatic portion 660.”<\/em><\/p>\n\n\n\n

    Cockerell’s work in New Mexico has always interested me, and some of his species have been most difficult to find and identify. Re-reading this description makes me like him even more — he uses microns for measurements and also refers to the two sections of the 6th antennal segment as 6a and 6b, both practices that I have used and been criticized for. I feel vindicated. That said, we must note that this description provides very little useful information in recognizing the species. Thank goodness for the relatively unusual host plant!<\/p>\n\n\n\n

    You’ll notice that he uses a couple old-fashioned terms for body parts: nectary = siphunculus = cornicle; beak = rostrum; bristles = setae = hairs.<\/p>\n\n\n\n

    The first time I found what I think is this species was in early October of 2012 in Grant County, New Mexico, in the Gila National Forest, Railroad Canyon. I recorded the host plant as Potentilla<\/em>, but at the time I had never knowingly seen Agrimonia before, so it is possible that I misidentified the plant. I see that Agrimonia striata<\/em> is common in the Gila National Forest, so who knows what I was looking at. Targeting Agrimonia<\/em> on our 2014 New Mexico expedition, I was able to find 2 alatae in the Lincoln National Forest near nogal Peak on 28 September. My one sample from Potentilla gracilis<\/em> was from the Uncompahgre National Forest in western Colorado in July of 2022, and I am almost 100% certain about my plant identification in this case. These two specimens fit M. agromoniellum<\/em> quite well except the ultimate rostral segment looks a bit longer and perhaps the hairs on it are finer. <\/p>\n\n\n\n

    As I wrote in my essay about Macrosiphum euphorbiae<\/em><\/a>, clues that this species is not M. euphorbiae<\/em> include the extra rhinaria on antennal segment III in both apterae and alatae, the usual lack of lateral tubercles at the base of siphunculi, and the slightly longer and hairier ultimate rostral segment.<\/p>\n\n\n\n

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    Macrosiphum albifrons<\/em> Essig<\/strong><\/p>\n\n\n\n

    This aphid is one of the largest in the world, and is actually familiar to many flower gardeners: it feeds on lupins (Lupinus<\/em>) and is sometimes called the ‘lupin aphid.’ It is widespread in North America and has spread elsewhere as well with its cultivated lupin hosts.<\/p>\n\n\n

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    \"Macrosiphum<\/a>
    Macrosiphum albifrons aptera<\/figcaption><\/figure>\n<\/div>\n\n\n

    In natural systems, M. albifrons<\/em> seems to be able to feed on many species of Lupinus<\/em>, however, some samples seem to differ morphologically from others. I have suspected that more than one species may be involved, but have not had the time, resources, etc. to study the situation in detail.<\/p>\n\n\n\n

    One similar species is Macrosiphum zionense<\/em> (see below), which lives on a lupin-like legume called Thermopsis<\/em> in the mountains of inland western North America. M. zionense<\/em> is usually yellow or orange and has dark antennae, siphunculi, and legs. Another nominal species, Macrosiphum thermopsaphis<\/em>, was described from Thermopsis<\/em> in Colorado back in 1938 by G.F. Knowlton. It was never recovered after the original collections and was sunk as a synonym of M. zionense<\/em> in 1997.<\/p>\n\n\n\n

    During spring of 2024 I studied my samples identified as M. albifrons<\/em> and M. zionense<\/em> that were collected on Thermopsis<\/em>. A key reason for this was to ascertain whether the pale green specimens I had collected over the years on Thermopsis<\/em> were in fact M. albifrons<\/em> as I had guessed. I was finally prompted to do this analysis by two collections in 2023 in which I found typical M. zionense<\/em> with yellow\/orange color and dark appendages together with specimens of the size and coloration of M. albifrons<\/em>. Both forms were extremely abundant on large patches of Thermopsis<\/em>, one in the La Sal Mountains of eastern Utah, the other in far western Colorado on Uncompahgre Butte. These sites are actually visible one from the other, perhaps 25 miles apart by air. Anyhow, looking at these samples of pale specimens on Thermopsis<\/em>, it was clear that the specimens did not fit either M. albifrons<\/em> nor M. zionense<\/em>. They had fewer rhinaria on antennal segment III than M. albifrons<\/em>, but more than M. zionense<\/em>. Also, the fourth antennal segment was about the same length as the third segment. In short, the pale specimens on Thermopsis<\/em> were easily<\/span> separated morphologically from both other species. So, I referred to Knowlton’s original description of M. thermopsaphis<\/em>. Here is what he said: “Apterous vivipara<\/span>.-Color light green with a dorsal covering of grayish pulverulence… Taxonomy<\/span>.- Macrosiphum thermopsaphis<\/em> differs from M. zionesis<\/em> Knlt. [sic] in having pale cornicles, shorter hind tarsi, and more secondary sensoria; it differs from M. albifrons<\/em> Essig in possessing fewer sensoria on antennal III of aptera, and in antennal IV being almost equal to or longer than III, rather than 0.14 to 0.3 mm. shorter.” It turns out that my samples fit Knowlton’s notes perfectly. I therefore have labeled these slides and noted them in my collection database as M. thermopsaphis<\/em>. This action is of course not an official nomenclatural change — it is for entertainment here on AphidTrek. Interestingly, I have a sample collected in the La Sal Mountains site from Lupinus<\/em> at the same time. These are typical M. albifrons<\/em> in terms of rhinaria and antennal segments. One of course wonders whether ‘M. thermopsaphis<\/em>‘ could be of hybrid origin, but until the unlikely event that someone studies the issue, I think it best to highlight this distinct form using Knowlton’s name.<\/p>\n\n\n

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    \"Macrosiphum<\/a>
    Macrosiphum albifrons aptera posing for her photo.<\/figcaption><\/figure>\n<\/div>\n\n\n

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    Macrosiphum badium<\/em> Jensen<\/strong><\/p>\n\n\n\n

    I studied this species extensively during my Ph.D. research in Oregon, where it was common in the forests living on Smilacina<\/em> (a.k.a. Maianthemum<\/em>, false lily of the valley). The description was published in 2000 when I wrote, “This species is monoecious, holocyclic, feeding on Maianthemum racemosa<\/em>, M. stellata<\/em> and M. dilatatum<\/em> (Liliaceae). Egg hatch occurs during March in Oregon\u2019s Willamette Valley as the plants are unfolding. Reproduction continues until June, when the apterae present at the time mature, and enter what appears to be a reproductive diapause through the summer. These apterae settle either among the fruits, when present, or on the lower leaves. Reproduction begins again in September, usually on the lower or most yellow leaves. The apterae that survive the summer give birth to oviparae and males. Eggs are laid below the surface of the soil along the plant stem. Males have only been observed in nature twice, despite many sincere efforts. The first apterous male was collected on the outside of a cloth bag enclosing a plant that had several oviparae on it. In 1994, males were quite easy to find throughout my normal collecting areas in McDonald State Forest. Some plants had several males, both alate and apterous. This occurred even though populations of the aphid overall were not dramatically higher than other years.”<\/p>\n\n\n\n

    In 2000 this aphid was only known from Washington and Oregon, but I have since collected it in Idaho and Montana.<\/p>\n\n\n

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    \"Macrosiphum<\/a>
    Macrosiphum badium <\/em>aptera from the Cascade Range in Washington.<\/figcaption><\/figure>\n<\/div>\n\n\n

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    Macrosiphum californicum<\/em> (Clarke)<\/strong><\/p>\n\n\n\n

    This is the name used for Macrosiphum<\/em> feeding on species of Salix<\/em> (willow).  Based on 30 years of collecting, it is clear to me that there are at least three species of Macrosiphum<\/em> using Salix<\/em> as host.  Let’s get into the details I have about this situation.<\/p>\n\n\n\n

    First it’s important to establish what we know about the original material and description of the nominal species, M. californicum<\/em>. W.T. Clarke coined the name and described this species in 1903 from what was apparently a single sample (single specimen?) collected at Newcastle, California (northeast of Sacramento) on an unknown date within the 18 months previous to publication of the paper. He wrote:<\/p>\n\n\n\n

    “<\/em>Californica, n. sp. — Apterous viviparous female.
    Length of body, 1.92 mm; width, .77 mm. Length of joints of antennae: III, .35mm; IV, .38 mm; V, .50 mm; VI, .19 mm; VII, 1.08 mm. General colour green. Joints of the antennae and the tarsi black. Rostrum reaching to second coxae, tip black. Nectaries yellow-green, reaching beyond tip of abdomen. Eyes pale.
    Small colonies on tips of new growth of willow. No winged individuals present. Newcastle.”<\/em><\/p>\n\n\n\n

    At first glance this description might seem devoid of useful information, but Clarke actually chose some good features to highlight here: the color green, the pigmentation of antennal joints, the lengths of antennal segments, and the fact that specimens were in small colonies on tips of new growth. I’ll come back to these features in a bit.<\/p>\n\n\n\n

    Now that we have this basic original information, where to go from here? I know. Let’s look at all the relevant material in my collection: 137 slides representing well over 100 samples and over 200 specimens from 9 U.S. states and 3 Canadian provinces. <\/p>\n\n\n\n

    What a luxury it is to attempt taxonomic clarification with lots of material rather than the old-fashioned way of evaluating species based on one to a few specimens! As I sorted, consistent differences emerged that I had not seen before. First of all, it was very easy to sort most of the material into three quite consistent groups that most likely represent species. Let me summarize these three, then cover what we can conclude about whether any of these is likely to be M. californicum<\/em> as seen by Clarke, then consider what should be done with the whole situation.<\/p>\n\n\n\n

    Macrosiphum<\/em> ex Salix<\/em> with ~5 pairs of cauda setae<\/span><\/p>\n\n\n\n

    This form is distinctive from the other two by having usually 5 pairs of lateral setae on the cauda; setae on antennae and middle parts of tibiae are longer, those on tibiae often trying to be fine and wavy; lateral and spinal tubercles are usually (always?) absent; ANT III is usually shorter than ANT V; ANT VIa (Base) is long, typically greater than 0.22 mm, up to about 0.34 mm; the R IV+V looks a bit broader and shorter, with about 6 accessory setae; the ventral surface of the head between clypeus and lateral margin has a distinct band of tiny spinules. In life the viviparae of this species are green or yellowish green with a dark green internal longitudinal stripe as in the photo below (this photo represents this form); the oviparae are orange with a darker orange internal longitudinal stripe, and my only note on alate male color is “yellow.” My samples of this form are all from the mountains in Oregon, Colorado, and Wyoming living in wet places on tall shrubby Salix<\/em> species (alas I have zero knowledge in recognizing species of Salix<\/em>). I have yet to collect an alate vivipara, these being rare in the sites I’ve gotten this form. Oviparae are abundant and easy to find.<\/p>\n\n\n

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    \"\"<\/a>
    Macrosiphum on Salix from the Warner Mountains of Oregon in September of 2018.<\/figcaption><\/figure>\n<\/div>\n\n\n

    Macrosiphum<\/em> ex Salix<\/em> with ~3 pairs of cauda setae and ANT VIa short<\/span><\/p>\n\n\n\n

    This form is the one I most commonly see in small to large colonies on growing tips of various Salix species and habitats from lowlands including the ocean coast to moderate elevation in the mountains. It is distinctive from the other two forms by having cauda elongate, nearly parallel-sided, with usually 3 pairs of lateral setae; ANT VIa not long, i.e., about 0.18 to 0.24 mm; antennae are often brown in alatae and dusky to brown in apterae, which have darker brown joints; ANT III is longer than ANT V; lateral and spinal tubercles are usually absent or very small on the abdomen; R IV+V has 4, sometimes 5 accessory setae; siphunculi in alatae are often brown beyond the basal fifth or so, sometimes brown in apterae as well; tibiae in alatae are often light brown and sometimes try to be brown in apterae. This is a very narrow-bodied form. In life it is green, usually without, but sometimes with a faint internal longitudinal darker green stripe. Interestingly, I have never seen sexuales nor fundatrix of this form. Does it host alternate? If so, I’m without ideas as to its primary host. I have material of this form from Washington, Oregon, California, and Idaho.<\/p>\n\n\n\n

    Macrosiphum<\/em> ex Salix<\/em> with ~3 pairs of cauda setae that also uses Cornus<\/em> as host<\/span><\/p>\n\n\n\n

    For many years I’ve been collecting a large pale Macrosiphum<\/em> on Cornus sericea<\/em> (I’ve always called it Cornus stolonifera<\/em>). This form was always evident in the spring, when it formed a generation of alatae, and again in the fall when I could find it re-colonizing Cornus<\/em> and producing sexuales. One day about a decade ago I was collecting and realized that any time I found this form on Cornus<\/em> there was Salix<\/em> nearby and that in the late spring and summer the Salix<\/em> often had a very similar aphid colonizing it. Aha! I thought. These may be the same species using both Cornus<\/em> and Salix<\/em> and that Cornus<\/em> is apparently the primary host. Then for some years I lived in the high elevation dry forest habitat of south-central Oregon and had this plant-aphid system almost in my back yard. I was able to collect more samples from both plants that supported the host alternation, in terms of timing and morphological similarity, and I was able to do a couple reasonably conclusive host plant transfers from Cornus<\/em> to Salix<\/em> in spring.<\/p>\n\n\n\n

    This week’s evaluation of all my samples allowed me to further define the morphological features that unite all this material within and between the two host plants. These features are: cauda triangular, with pointy tip, usually with 3 pairs of lateral setae, sometimes 4; ANT III longer than ANT V; lateral tubercles usually prominent on abdominal segments 2-6; spinal tubercles usually present, sometimes quite broad and prominent on abdominal tergites VII and VIII and on the head; R IV+V usually with 6, sometimes 7 accessory setae; siphunculi are constricted apically with a slightly swollen portion basad. The alatae are usually light green or yellowish, the oviparae and alate males are white, or what I called “whitish green.” I have material of this form from British Columbia, Alberta, Washington, Oregon, Idaho, Montana, Utah, New Mexico, and Colorado.<\/p>\n\n\n\n

    Miscellaneous samples<\/span><\/p>\n\n\n\n

    As is so often the case when sorting large numbers of samples from diverse locations and habitats, I have several samples that don’t match any of these three larger categories. A couple samples from Wyoming seem to be intermediate in appearance, a sort of blend of the forms I discuss above. One sample from New Brunswick, Canada is also a bit off, not quite fitting the other forms I sorted out. A few samples from coastal parts of Washington, Oregon, and California look different from all others. I remember collecting a sample from the Oregon coast on a Salix<\/em> growing on the margins of the sandy beach. These specimens had a strange posture on the plant, being closely appressed to the leaf, with antennae laid flat forward of the head rather than swept back as is typical of many aphids. Based on this variability and extreme habitats that are Pacific Ocean beaches and coastal habitats, I suspect that at least one more species could be delimited with adequate collecting on the Pacific coast. The same might be possible through collecting along the east coast of North America, based on my single sample from New Brunswick. All of this of course ignores Mexico, which I know has a fair bit of Macrosiphum<\/em> diversity.<\/p>\n\n\n\n

    What name(s) to use, then?<\/span><\/p>\n\n\n\n

    This mini-essay about M. californicum<\/em> has been progressing from least nerdy to most nerdy topics. The most nerdy issue is, what name or names to use for these forms that seem to be 3 separate species? The name used over the past century has been Macrosiphum californicum<\/em> (Clarke) because E.O. Essig suggested this some years after publishing the name Macrosiphum laevigatae<\/em> Essig, 1911 and subsequently deciding that it should be a synonym of M. californicum<\/em>. If Essig’s and Clarke’s names were referring to the same species, then the rule is that the older name take priority, i.e., M. californicum<\/em>. A key question then becomes, are these two names referring to the same species? A second key question is, do these names seem to be appropriate for any of the three forms I discuss above? <\/p>\n\n\n\n

    Regarding the first of these questions, the short answer is that we will never know for sure because Clarke’s types (or perhaps better referred to as Clarke’s original material since I’m not sure he formally designated types) are lost and presumed destroyed in the massive fire that burned most of San Francisco in 1906<\/a>. So, to determine whether the name M. californicum<\/em> applies to Essig’s samples from his 1911 paper, must compare the descriptions. They both provide very little useful information. The most useful feature that they both mention is the length of antennal segments. Clarke’s numbers show that the ANT VIa was on the short side for these forms, i.e., 0.19 mm but that ANT V was substantially longer than ANT III. These two facts seem to not fit any of my forms since the one I have with ANT V longer than ANT III also has a long ANT VIa, nor do they fit M. laevigatae<\/em> which had ANT V shorter than ANT III and ANT VIa with length about 0.22 mm in apterae. Clarke’s material came from inland California in the foothills of the Sierra Nevada Mountains, while Essig’s material came from the California coast. So, based on this and evaluation of my samples, it is reasonable to think that these names applied to two different species. I found some cryptic notes I wrote at some point in the past that suggested I had seen Essig’s types of M. laevigatae<\/em> but that I was unable to confidently link them to anything I had seen at that time (those notes are probably from 2010 or so). Bottom line answers to these two questions are: 1) It is not possible to tell based on the descriptions whether Essig and Clarke were looking at the same form; 2) I don’t think M. californicum<\/em> clearly applies to any of the three forms I have sorted from my material. I suspect one or more of my coastal samples would be more likely as good specimens of Clarke’s M. californicum<\/em> and there is no way to be sure what Essig was looking at without seeing his material again and possibly collecting fresh material from his locality (Santa Paula, California).<\/p>\n\n\n\n

    Conclusions<\/span><\/p>\n\n\n\n