Capitophorus elaeagni

Identification & Distribution:

Apterae in spring populations of Capitophorus elaeagni on the primary host are pale green. Their abdominal dorsum is reticulate or sculptured. Each of abdominal tergites I-IV usually have 2 spinal, 2 pleural and 2 marginal hairs (cf. Capitophorus similis  which has 4 spinal, 4 pleural and 6 marginal hairs on each of tergites I- IV). The siphunculi are cylindrical or tapering and are dusky to dark at the apices (cf. Capitophorus carduinus  which has siphunculi which are not dark at the apices). The body length of wingless viviparae on the primary host is 1.9-2.5 mm. Wingless viviparae on the secondary host (various Compositae) are greenish white to yellowish green with dark tips to the siphunculi. The body length of wingless viviparae on the secondary host is 1.4-2.5 mm.

Winged viviparae produced on the primary host have a black head and thorax, black antennae and a blackish dorsal abdominal patch.

Note: our identification of these aphids as Capitophorus elaeagni was not checked microscopically. Blackman (2010) indicates that the sexual phase of Capitophorus elaeagni that occurs on Elaeagnus in continental Europe has not yet been recorded in Britain, casting doubt on our identification. It could instead be Capitophorus similis which host alternates between Elaeagnus and Tussilago or Petasites. That said, we observed these forms in the south coast which, if sexual forms of Capitophorus elaeagni occur in Britain, is the most likely place to find them.

The clarified slide mounts below are an adult viviparous female Capitophorus elaeagni : wingless and winged.

Micrographs of clarified mounts  by permission of Roger Blackman, copyright AWP  all rights reserved.

The common oleaster aphid host alternates from oleaster (Elaeagnus) or sea buckthorn (Hippophae) to various thistles and daises (Asteraceae). Capitophorus elaeagni is found over most of the temperate, and warm temperate, parts of the world.

Other aphids on same host:

Capitophorus elaeagni has been recorded from 8 Elaeagnus species, and 1 Hippophae species (Hippophae rhamnoides =Elaeagnus rhamnoides, sea buckthorn).

Blackman & Eastop list 10 species of aphid  as feeding on oleaster (Elaeagnus species) and/or sea buckthorns (Hippophae species) worldwide, and provide formal identification keys.

Of those aphid species, Baker (2015)  lists 4 as occurring in Britain: Capitophorus hippophaes,  Capitophorus elaeagni, Capitophorus similis  and Capitophorus pakansus.

Acknowledgements Our particular thanks to Roger Blackman for images of his clarified slide mounts. We have made provisional identifications from high resolution photos of living specimens, along with host plant identity. In the great majority of cases, identifications have been confirmed by microscopic examination of preserved specimens. We have used the keys and species accounts of Blackman & Eastop (1994)  and Blackman & Eastop (2006)  supplemented with Blackman (1974) , Stroyan (1977) , Stroyan (1984) , Blackman & Eastop (1984) , Heie (1980-1995) , Dixon & Thieme (2007)  and Blackman (2010) . We fully acknowledge these authors 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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