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Aphididae : Aphidinae : Macrosiphini : Ovatomyzus
 

 

Genus Ovatomyzus

Borage aphids

On this page: Ovatomyzus boraginacearum chamaedrys

Genus Ovatomyzus [Macrosiphini]

Ovatomyzus are a genus of very small fragile pale aphids, the adult viviparae of which may be winged or wingless. The characteristics of the genus are intermediate between Ovatus and Myzus. Ovatomyzus apterae have well developed antennal tubercles with slightly diverging inner margins. The antennae are as long as the body, or longer, with a very long terminal process. The siphunculi are long, slender, cylindrical or slightly swollen. The cauda is tongue shaped, slightly constricted near the base.

There are 3 species worldwide. Ovatomyzus have lost the sexual stage in their life cycle, and feed all year round on plants in the Lamiaceae and Boraginaceae.

Ovatomyzus boraginacearum (Alkanet aphid) Europe, Middle East

Adult apterae of Ovatomyzus boraginacearum (see first two pictures below) are usually whitish to pale greenish yellow, but may be brownish yellow to orange in overwintering populations. Their antennal tubercles are smooth and well developed. The pale antennae are longer than the body, and the terminal process of antennal segment VI is 1.5-2.3 times the length of antennal segment III. The pale siphunculi do not have any distinct subapical polygonal reticulation, and are slightly swollen subapically, narrowing to a slight constriction before the flange. Ovatomyzus boraginacearum is a very small aphid, with a body length of only 0.9-1.6 mm.

The Ovatomyzus boraginacearum alate (see third picture above) has a black dorsal abdominal patch and cross bars on the posterior tergites. The antennae and legs of the alate are dark, the siphunculi and cauda are dusky.

The alkanet aphid lives scattered on the undersides of leaves of its host plants, which are mainly in the family Boraginaceae, especially alkanet (Pentaglottis), lungwort (Pulmonaria officinalis) and comfrey (Symphytum officinale), and less commonly in the family Dipsacaceae. Ovatomyzus boraginacearum does not have sexual forms, but is reported to have a specialized hibernating apterous morph. It has been found in several European countries including England, Germany and Netherlands, as well as in Iran.

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Ovatomyzus chamaedrys (Woodsage aphid) Europe, West Asia

Adult apterae of Ovatomyzus chamaedrys (first picture below, or it may be a fourth-instar) are yellowish white to whitish green, darker at colder temperatures. Their antennae are 1.1-1.6 times the body length, with the terminal process 5.6-7.7 times as long as the base of antennal segment VI (cf. Ovatomyzus boraginacearum, which has the terminal process 4.5-6.0 times the base of that segment). The longest hair on segment III is 0.1-0.2 times the length of the basal diameter of that segment. The antennal tubercles are distinctly developed. The apical segment of the rostrum (RIV+V) is 1.2-1.5 times the second hind tarsal segment (HTII). The siphunculi are pale and slightly swollen on the distal half with a distinct flange (cf. Ovatomyzus stachyos, which has the siphunculi tapering or cylindrical and almost flangeless). The siphunculi are 2.2-3.1 times the caudal length. The cauda is tongue-shaped, with a distinctly constricted base and 5(-7) hairs. The body length of adult Ovatomyzus chamaedrys apterae is 0.8-1.5 mm.

Both images above by permission, copyright Dirk Baert, all rights reserved.

Alatae of Ovatomyzus chamaedrys (not pictured) have a black dorsal abdominal patch, and antennae that are 1.1-1.4 times the length of the body. They bear 31-36 secondary rhinaria on antennal segment III, 11-15 on segment IV, and 0-4 on segment V. The siphunculi of alatae are about 2.4 times the length of the cauda.

Ovatomyzus chamaedrys lives on the undersides of leaves of certain members of the Lamiaceae, especially wild basil (Clinopodium vulgare) and several species of germander (Teucrium spp.) as well as on small scabious (Scabiosa columbaria) and purple gromwell (Lithodora diffusa = Glandora diffusa). There are records from several other Lamiaceae (Ajuga genevensis x pyramidalis, Calamintha sp., Marsypianthes chamaedrys, Mentha spp. Stachys heraclea) and, less certainly, two Boraginaceae species. Ovatomyzus chamaedrys populations are entirely anholocyclic. The woodsage leaf aphid has been recorded from much of Europe, including Britain, and also from Kazakhstan.

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Acknowledgements

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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References

  • Blackman, R.L. & Eastop, V.F. (2006). Aphids on the world's herbaceous plants and shrubs. Vols 1 and 2. John Wiley & Sons.