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Aphidinae : Macrosiphini : Paczoskia obtecta
 

 

Paczoskia obtecta

Horned knapweed aphid

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

Identification & Distribution

Adult apterae of Paczoskia obtecta are shiny bronze brown with dark spots, and have bright red eyes (cf. Uroleucon spp. such as Uroleucon jaceicola & Uroleucon jaceae which have dark brown eyes). The antennae (except at base of segment III), siphunculi and cauda are black, and the legs are yellowish with dark segmental apices. The antennal tubercles are also shiny black, and unusually well developed (see second picture below of close-up showing enlarged antennal tubercles) (cf. Uroleucon spp. which do not abnormally large antennal tubercles). The antennae are 1.0-1.5 times the body length, with the terminal process 4.9-6.1 times as long as the base of antennal segment VI. There are 32-50 secondary rhinaria on the basal 0.75 of antennal segment III. The apical segment of the rostrum (RIV+V) is 1.0-1.1 times the length of the second hind tarsal segment (HTII). The bases of the siphunculi are almost ringed by large semicircular antesiphuncular, and less extensive postsiphuncular, sclerites (see first picture below) (cf. Uroleucon spp. which have the antesiphuncular sclerites either absent or fragmented). There are also marginal sclerites. The siphunculi are 1.4-1.6 times the caudal length, with reticulation on the apical 20-35%. The cauda is very long and slender with 9-15 hairs. The body length of adult Paczoskia obtecta apterae is 3.1-4.3 mm.

Image above, by permission copyright Nick Peeters, all rights reserved.

The alate Paczoskia obtecta (see picture below) is similar to the aptera, except it has a black head and thorax and larger marginal sclerites.

Image above, by permission copyright Nick Peeters, all rights reserved.

Paczoskia obtecta is monoecious on knapweed (Centaurea spp.). It feeds on the undersides of the lower leaves, and later on the upper parts of stems. It is most likely holocyclic like several other members of the genus, but sexuales are so far unknown. Paczoskia obtecta has so far been found in France, Sweden, Denmark, Germany, Poland, Austria, former Yugoslavia, Hungary and the Czech Republic, and (with this record) now in the Netherlands. It has also been found in Israel.

 

Other aphids on the same host

Paczoskia obtecta has been recorded on 8 species of knapweed (Centaurea arista, Centaurea aspera, Centaurea cyanus, Centaurea jacea, Centaurea procurrens, Centaurea scabiosa, Centaurea solstitialis, Centaurea triumfetti).

Acknowledgements

We are grateful to Nick Peeters for permitting us to reproduce his excellent images of Paczoskia obtecta, and to Jochem Kuhnen for putting him in touch with us.

We have used the species account given by Heie (1995) (as Macrosiphoniella obtecta) 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

  • Heie, O.E. (1995). The Aphidoidea (Hemiptera) of Fennoscandia and Denmark. VI.Fauna Entomologica Scandinavica 31:24 31, 1-222.