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Aphidinae : Macrosiphini : Macrosiphum vancouveriae
 

 

Macrosiphum vancouveriae

Inside-out-flower aphid

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

Identification & Distribution

Adult apterae of Macrosiphum vancouveriae are very pale green to white, with reddish-brown eyes. The appendages are mostly pale, but the apices of antennal segments IV & V, all of segment VI, tips of the tibiae, all of the tarsi, and the distal half (or less) of the siphunculi are dusky. The head often has low spinal tubercles. The antennal tubercles are moderately large and diverging, and the median frontal tubercle is small but distinct. The rostrum reaches to mesocoxae, with the apical rostral segment (RIV+V) 0.77-0.92 times the second hind tarsal segment (HTII). The prothorax has indistinct marginal tubercles. The abdominal tergum is uniformly sclerotic, and somewhat wrinkled. Tergites II-V sometimes have low, indistinct marginal tubercles. Dorsal setae are narrowly blunt to pointed (cf. Macrosiphum violae, which has dorsal hairs slightly capitate to blunt). Tarsal segment I has 3 hairs (cf. Macrosiphum tuberculaceps, also on Berberidaceae, which has 4 hairs on tarsal segment I). The siphunculi are 0.69-1.10 times as long as antennal segment III, with about 10 rows of reticulations apically. The cauda has 7-11 hairs. The body length of adult Macrosiphum vancouveriae apterae is 2.2-3.8 mm.

First image above copyright Andrew Jensen,second image Emily Scherer;
both under a creative common licence.

Alate Macrosiphum vancouveriae are more-or-less white, but with the sclerotized areas conspicuously brown. The abdomen has large, brown pleural and spinal intersegmental sclerites. The marginal sclerites are usually pale, sometimes with small, dense, pigmented areas within them. The apical half of the siphunculi and the cauda are dusky. Antennal segment III has 7-12 secondary rhinaria, scattered in a single row over approximately the basal three quarters. The head has spinal tubercles, often large ones, and the antennal tubercles are large and diverging. The siphunculi are 0.75-0.86 times as long as antennal segment III. The cauda has 9-12 hairs.

Macrosiphum vancouveriae is monoecious on white inside-out flower (Vancouveria hexandra). The life cycle is uncertain, but alate males and oviparae have been found in October-November. Jensen (2000), who first described this species, notes that it often lives in the same forests as Macrosiphum tuberculaceps, which occurs on related herbs in the Berberidaceae. Macrosiphum vancouveriae most resembles Macrosiphum violae, but attempts to transfer Macrosiphum vancouveriae to the host of that species (Viola glabella) were unsuccessful. Jensen comments that the aphid was fairly easy to find in the McDonald State Forest in Oregon, but elsewhere it is rare indeed. He has only found it in recent years in the Rogue-Umpqua Divide Wilderness in southwest Oregon. Macrosiphum vancouveriae is only known from north-western USA.

 

Other aphids on the same host

Macrosiphum vancouveriae has so far only been recorded on 1 plant species: Vancouveria hexandra.

  • Blackman & Eastop list 1 species of aphid Macrosiphum vancouveriae as feeding on white inside-out flower (Vancouveria hexandra) worldwide. This species is not listed by Baker (2015) as occurring in Britain.

Acknowledgements

We are grateful to Andrew Jensen and Emily Scherer for making their images, of Macrosiphum vancouveriae & Vancouveria hexandra respectively, available for use under a creative commons licence.

We have used the species account given by Jensen (2000), with additional 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 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).

Useful weblinks

References

  • Jensen, A.S. (2000). Eight new species of Macrosiphum from Western North America, with notes on four other poorly known species. Proceedings of the Entomological Society of Washington 102(2), 427-472. Full text