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Calaphidinae : Panaphidini : Neosymydobius paucisetosus
 

 

Neosymydobius paucisetosus

Red-headed brown oak aphid

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

Identification & Distribution

In life, adult apterae of Neosymydobius paucisetosus have a red-brown head. Their dorsum colour varies from dark brown with some pale patches to very pale brown with slightly darker brown patches (see two pictures below). Antennal segments I and II are brown, segments III-V are pale fuscous with black apices, and segment VI black. The base of antennal segment VI has only 1-5 (rarely 7) hairs (cf. Neosymydobius agrifoliae, which has 10-20 hairs on the base of antennal segment VI). The pronotum has anterior and posterior sclerites separated. There is very little (or no) spinal or pleural sclerotization on the mesonotum, metanotum, and abdominal tergites I-VI, but they may or may not have small sclerites or scleroites present (cf. Neosymydobius albasiphus, which has a large tranverse sclerotic band on each of tergites I-V). The abdominal sclerites may be larger on the posterior abdomen, and on tergites VI-VIII they form transverse sclerotic bands. In addition there are weakly sclerotized, roundish brown marginal sclerites on each abdominal segment. The femoral hairs are blunt and rather short, up to 0.025 mm long (cf. Neosymydobius rumorosensis, which has hairs on the femora pointed with wavy apices, the longest up to 0.045mm) The hind tibiae are mostly pale in the middle (cf. Neosymydobius agrifoliae, which has most of the hind tibiae uniformly black). The siphunculi are sclerotic, with a pale apical flange. The cauda is rounded, tongue-shaped, with a posterior sclerotic margin bearing 20-30 hairs. The body length of adult Neosymydobius paucisetosus apterae is 1.7-2.5 mm.

Note: The only difficult issue in identifying Neosymydobius species in California is to distinguish Neosymydobius paucisetosus from, the longer-haired, Neosymydobius rumorosensis. Both species have limited sclerotization and a pale area mid-tibiae. The contributor of these images measured the femoral hairs at 'about 20μm', which is well within the range for Neosymydobius paucisetosus.

Images above copyright Jesse Rorabaugh under a public domain (CCO) licence.

Alatae (not pictured) are coloured much the same as apterae. The wings have pigmentation along the costal margin and sometimes diffuse brown mottling on the pterostigma. Other veins have diffuse pale brown bordering, particularly beside vein Cul b. Antennal segment III bears 3-8 secondary rhinaria.

Images above copyright Jesse Rorabaugh under a public domain (CCO) licence.

Neosymydobius paucisetosus feeds on various western American oak species, including California live oak (Quercus agrifolia), canyon live oak (Quercus chrysolepis, blue oak (Quercus douglasii), coastal sage scrub oak (Quercus dumosa), valley oak (Quercus lobata) and interior live oak (Quercus wislizeni). It is closely related to Neosymydobius agrifoliae (Quednau, 1994). Neosymydobius paucisetosus is monoecious holocyclic, with sexuales having been found in September-October. So far Neosymydobius paucisetosus has only been recorded in California, USA.

 

Other aphids on the same host

Neosymydobius paucisetosus occurs on 6 oak species (Quercus agrifolia, Quercus chrysolepis, Quercus douglasii, Quercus dumosa, Quercus lobata, Quercus wislizeni).

Acknowledgements

We are grateful to Jesse Rorabaugh (glmory) for the pictures of Neosymydobius paucisetosus that he has made available to everyone under a 'public domain' (CC0) licence (for more of his excellent pictures see).

Identification was made by Jesse Rorabaugh and by us from the photos of living and preserved specimens. We have used the keys and species accounts of Quednau (1994) together 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).

Useful weblinks

References

  • Quednau (1994). Taxonomic notes on the genus Neosymydobius Baker with descriptions of five new species (Homoptera: Aphididae). The Canadian Entomologist 126, 1443- 1458. Abstract