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Dark-legged goldenrod aphidOn this page: Identification & Distribution Other aphids on the same host
Identification & Distribution
Adult apterae of Uroleucon nigrotibium have the entire body red-brown (cf. Uroleucon cadens, Uroleucon caligatum, Uroleucon erigeronense and Uroleucon gravicorne, which have the body green). Their antennae are mainly dark with 7-16 secondary rhinaria on antennal segment III (cf. Uroleucon atripes, which has 13-47 secondary rhinaria on that segment). Marginal sclerites are dusky and broken, and scleroites are dusky and larger than those of alate viviparae. The second hind tarsal segment (HTII) is shorter than the apical rostral segment (RIV+V), and shorter than antennal segment I. The legs have the proximal half of the femora pale, and the distal half dark dusky to dark. The tibiae are almost uniformly dark (cf. Uroleucon solidaginis, which has tibiae with a pale section in the middle). The first hind tarsal segment (HTI) has 3 hairs (cf. Uroleucon atripes, which usually has 5 hairs on HT I). Abdominal tergite VIII usually has 2 hairs (cf. Uroleucon atripes, which usually has 4 hairs on abdominal tergite VIII). The siphunculi are entirely dark and the cauda is pale.
Both images above by permission, copyright Claude Pilon, all rights reserved.
Alate Uroleucon nigrotibium viviparae are similarly coloured to the apterae. They have 14-39 secondary rhinaria on antennal segment III. There are dusky marginal sclerites on abdominal segments II, III, and IV, all bearing small transparent marginal tubercles. The antesiphuncular sclerites are broken, but postsiphuncular sclerites are large and entire.
The images below show (first) a colony of Uroleucon nigrotibium on its host plant, and (second) a clarified mount of an alate Uroleucon nigrotibium.
Uroleucon nigrotibium appears to be restricted to a few species of goldenrod, especially grey goldenrod (Solidago nemoralis) and sweet goldenrod (Solidago odora). These aphids fall readily from their host when disturbed, much like Uroleucon cadens and Uroleucon crepusisiphon. All three species produce few winged morphs, but apterae walk frequently between plants, thus initiating new colonies nearby (Moran, 1985). The species is known from the eastern states of the USA (Michigan, North Carolina) and from Canada (Quebec).
Other aphids on the same host
Uroleucon nigrotibium has been recorded on 2 or possibly 3 species of goldenrod (Solidago nemoralis, Solidago odora, ?Solidago microglossa).