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Aphidinae : Macrosiphini : Cedoaphis incognita
 

 

Cedoaphis incognita

Green snowberry aphid

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

Identification & Distribution

Adult apterae of Cedoaphis incognita are yellowish green with a dusky brown head. Their appendages are pale with dusky tips. The siphunculi are yellowish but dusky apically, and the cauda, anal and genital plates are brown. Antennal segments III-V have numerous secondary rhinaria along most of their length, with 13-28 on segment III, 8-18 on segment IV, and 1-8 on segment V (cf. Aphthargelia symphoricarpi, which has antennal segments III-V without rhinaria or with only 1-3 rhinaria near base of III). There are light brown transverse mid-dorsal bands on tergites VI-VIII. Abdominal tergites I-VII have flat round marginal tubercles (cf. Amphicercidus pulverulens & Amphicercidus flocculosus, which either have no marginal tubercles present, or if present they are very small, papilliform and restricted to abdominal tergites II-V). The siphunculi are cylindrical, with the flange imbricated. The cauda is short and rounded or helmet-shaped, not longer than its basal width in dorsal view and bearing at least 20 long fine hairs.

Note: Jensen in Aphidtrek suggests there are probably 2-4 species currently confused under the name Cedoaphis "incognita". He also points out that, although in most texts Cedoaphis is still given as monoecious, Cedoaphis incognita was described as Aphis chipetae on its secondary host, Indian paintbrush (Castilleja spp.) by Hottes (1933).

Images above copyright Andrew Jensen, under a cc by-nc-sa licence.

Cedoaphis incognita alatae (see second picture above of an alate Cedoaphis sp.) have secondary rhinaria on the antennae distributed III 22-28, IV 15-18, V 10-14. There are dark lateral spots anterior to the siphunculi and dark bands on abdominal tergites VI, VII, and VIII. The antennae, siphunculi, cauda and legs are blackish.

The primary hosts of Cedoaphis incognita are several species of snowberry (Symphoricarpos). Andrew Jensen in Aphidtrek reported finding Cedoaphis fundatrices (see picture below) in characteristic leaf curl galls at the end of snowberry branches, first noted by Oestlund (1887) (as Aphis symphoricarpi) on the leaves of Symphoricarpa vulgaris.

Image above copyright Andrew Jensen, under a cc by-nc-sa licence.

Jensen found there were two life cycle strategies for Cedoaphis incognita. Most spring leaf curl galls are abandoned by alate viviparae, which migrate to the crowns of Indian paintbrush (Castilleja spp.). Then in autumn males and female sexuparae migrate back to Symphoricarpos, where oviparae are produced. Alternatively some leaf galls remain occupied all summer, with sexuales produced in autumn. Whether these two strategies represent two different species is as yet unknown. We also note that finding fundatricices in leaf curls was contrary to the view of Gillette and Palmer (1932) who suggested that fundatrices lived on the roots in spring. Cedoaphis incognita is vigorously ant-attended on both Symphoricarpos and Castilleja. Cedoaphis incognita is widely distributed in the USA.

 

Other aphids on the same host

Primary host

Cedoaphis incognita has been recorded on 2 snowberry species (Symphoricarpos mollis, Symphoricarpos occidentalis) and (according to Oestlund, 1987), Symphoricarpos vulgaris (possibly = Symphoricarpos orbiculatus). It is the only aphid species recorded on Symphoricarpos mollis, apart from an (as yet) undescribed Aphthargelia species.

Secondary host

Cedoaphis incognita has been recorded on an unidentified species of Castilleja.

Acknowledgements

We are grateful to Andrew Jensen for making his images of Cedoaphis incognita available for use under creative commons licences.

Identification was made by Andrew Jensen by microscopic examination of preserved specimens. We have used the keys and species accounts of Oestlund (1887) (as Aphis symphoricarpi), Gillette and Palmer (1932) & Palmer (1952) (both as Aphis incognita), 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 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

  • Gillette, C.P. and Palmer, M.A. (1932). The Aphidae of Colorado, Part II. Ann. Ent. Soc. America 25, 369-496. Abstract (p. 407).

  • Hottes, F.C. (1933). Descriptions of Aphiidae from Western Colorado. Proceedings of the Biological Society of Washington 46, 1-24. Full text (p. 6)

  • Oestlund, O.W. (1887). Synopsis of the Aphididae of Minnesota. Bulletin of the Geological and Natural History Survey of Minnesota 4, 100 pp. (p.50)

  • Palmer, M.A. (1952). Aphids of the Rocky Mountain Region: including primarily Colorado and Utah, but also bordering area composed of southern Wyoming, southeastern Idaho and northern New Mexico. Thomas Say Foundation, Denver. Full text