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Aphidinae : Macrosiphini : Pleotrichophorus quadritrichus
 

 

Pleotrichophorus quadritrichus

Dark-tailed sagebrush aphid

On this page: Identification & Distribution Other aphids on the same host

Identification & Distribution

Adult apterae of Pleotrichophorus quadritrichus are bluish green, appearing grey-green over body. The antennae are longer than the body. The antennae are dark, apart from segments III and the proximal half of IV, which are dusky. Antennal segment III bears 1-2 secondary rhinaria, and the terminal process is 3-4 times as long as the base of segment VI. Hairs on the antennae are very short, less than 0.5 times basal diameter of segment III (cf. Pleotrichophorus heterohirsutus, which has the longest hair as long as or longer than the segment basal diameter). The antennal tubercles are moderately produced, with the median frontal tubercle rather low. The apical rostral segment (IV+V) is slender at the base, with the apical 0.33-0.50 produced into a thin, cylindrical needle. RIV+V is 1.08-1.30 times the length of the second hind tarsal segment (HTII). The dorsal body integument has a moderately dense cover of funnel- or cone-shaped hairs. The femora are dusky, the tibiae are pale and the tarsi are dark. Both the siphunculi and cauda are dark, except for subspecies pallidus where they may be dusky or rarely pale (cf. Pleotrichophorus gnapholodes, which has pale siphunculi & cauda). The siphunculi are cylindrical, and sparsely armed with small, blunt spicules; the siphunculi are 0.77-1.57 as long as cauda. The cauda is elongate, with a distinct constriction on the basal 0.25 (cf. Pleotrichophorus pullus, which has no such constriction). The cauda has an acute, but rounded apex, and has 2 pairs of lateral and 1-2 dorsal hairs. The body length of adult Pleotrichophorus quadritrichus apterae is 1.15-1.67 mm.

Images above copyright Andrew Jensen, under a creative common licence.

The alate vivipara of Pleotrichophorus quadritrichus has the head, thorax, antennae, legs, siphunculi and cauda all dark sclerotic. The abdomen is pale, membranous, with light brown spinal, pleural and marginal sclerites. Morphologically the alate is much like the aptera except there are more rhinaria on antennal segment III (2-7), the abdomen has 2 small spinal, 2 pairs of pleural and 2 marginal sclerites, and the dorsal hairs are smaller, sparser and less capitate.

Subspecies:

  • Pleotrichophorus quadritrichus quadritrichus, on Artemisia tridentata and Artemisia californica: The siphunculi & cauda are dark. Siphunculi are not more than 1.25 times as long as cauda. There is usually 1 rhinarium on antennal segment III. The terminal process averages 3.87 times as long as the base of antennal segment VI.
  • Pleotrichophorus quadritrichus vulgaris on Artemisia vulgaris: Siphunculi & cauda are dark, with siphunculi distinctly longer than cauda. There are usually 2 or more rhinaria on segment III. The terminal process is 3.75-5.25 times the base of antennal segment VI.
  • Pleotrichophorus quadritrichus pallidus on Artemisia tridentata: The coxae, trochanter and femora of all legs, siphuncul and cauda are pale or dusky. The siphunculi are about as long as the cauda.

Pleotrichophorus quadritrichus is monoecious holocyclic on several species of sagebrush (Artemisia ssp.) Oviparae and alate males occur in October. It is very active, and tends to run fast when disturbed. The dark-tailed sagebrush aphid is common and widespread in western states of the USA.

 

Other aphids on the same host

Pleotrichophorus quadritrichus and its subspecies have been recorded on 6 Artemisia species (Artemisia arbuscula, Artemisia californica, Artemisia cana, Artemisia rigida, Artemisia tridentata, Artemisia vulgaris).

Acknowledgements

We are grateful to Andrew Jensen for making his pictures available for use under a creative commons licence.

We have used the keys and species accounts of Knowlton & Smith (1936) and Corpuz-Raros & Cook (1974), along with information from Roger Blackman & Victor Eastop in Aphids on Worlds Plants. We fully acknowledge these authors and those listed in the reference sections as the source for the (summarized) taxonomic information we have presented. Any errors in identification or information are ours alone, and we would be very grateful for any corrections. For assistance on the terms used for aphid morphology we suggest the figure provided by Blackman & Eastop (2006).

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References

  • Corpuz-Raros, L.A & Cook, E.F. (1974). A revision of North American Capitophorus van der Goot and Pleotrichophorus Borner (Homoptera: Aphididae). Smithsonian Contributions to Zoology 156, 1-143 (p. 55) Full text

  • Knowlton, G.F.& Smith, C.F. (1936). Capitophorus aphids infesting Artemisia. The Canadian Entomologist 68(10), 229-234. Abstract