Dysaphis ranunculi

Identification & Distribution:

The curled-leaf gall (see first picture below) of Dysaphis ranunculi on hawthorn (Crataegus monogyna) its primary host is pale yellowish-green, often suffused with rosy pink (our gall was yellowish green but had no pink colour). There is no sharp demarcation between the pink of the gall and the green of the leaf lamina (cf. Dysaphis crataegi where such a demarcation is present). The Dysaphis ranunculi fundatrices are deep blue-grey with a wax bloom, and the immature offspring of the fundatrix are usually brownish grey to grey. The immature offspring in the gall shown below second were light green with wax markings - hence the identification of this gall as resulting from Dysaphis ranunculi, based on gall-appearance, may not be correct.

Winged forms arise in the second generation and the alates migrate to the basal parts of buttercups (Ranunculus spp.). On Ranunculus the adult Dysaphis ranunculi apterae are mottled grey-green, brownish around the bases of the siphunculi, wax dusted and with variable dark sclerotization. There are usually 9 or more secondary rhinaria on the fifth antennal segment (cf. Dysaphis crataegi where there are usually 0-1).

The clarified slide mounts below are of adult viviparous female Dysaphis ranunculi : fundatrix (from primary host), lightly sclerotized wingless from secondary host, and winged spring migrant.

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

The images below show confirmed Dysaphis ranunculi immatures living on the roots of the secondary host, Ranunculus (no other Dysaphis species live on Ranunculus.)

Dysaphis ranunculi colonies are attended by ants. There is a return migration to hawthorn in September. The hawthorn-buttercup aphid is found throughout Europe and in central Asia.

Other aphids on same host:

Dysaphis ranunculi has been recorded from 6 Crataegus species (Crataegus altaica, Crataegus laevigata, Crataegus ×lambertiana, Crataegus monogyna, Crataegus sanguinea, Crataegus submollis).

Blackman & Eastop list 16 species of aphid as feeding on common hawthorn (Crataegus monogyna) worldwide, and provide formal identification keys.

Of those aphid species, Baker (2015) lists 15 as occurring in Britain: Aphis fabae, Aphis gossypii Aphis pomi, Aphis spiraecola, Aulacorthum solani, Dysaphis angelicae, Dysaphis apiifolia, Dysaphis crataegi, Dysaphis lauberti, Dysaphis ranunculi, Ovatus crataegarius, Rhopalosiphum oxyacanthae, Ovatus insitus, Prociphilus pini and Rhopalosiphum rufulum.

Acknowledgements We especially thank Trees for Life for their kind assistance. Our particular thanks to Roger Blackman for images of his clarified slide mounts. Whilst we make every effort to ensure that identifications are correct, we cannot absolutely warranty their accuracy. We have mostly made 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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