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Aphididae : Calaphidinae : Panaphidini : Hoplochaitophorus
 

 

Genus Hoplochaitophorus

Spiny oak aphids

On this page: Hoplochaitophorus quercicola

Hoplochaitophorus [Panaphidini]

Hoplochaitophorus are oak-feeding aphids in North America that have Chaitophorus-like pigmented spiny dorsal hairs. Adult apterae have antennal tubercles undeveloped and the front of the head slightly concave. Their antennae are 6-segmented and the terminal process is short, not as long as the base of segment VI. Secondary rhinaria are present on antennal segment III. The rostrum is 4-segmented with a short triangular apical segment. The prothorax has several lateral tubercles. The head, thorax and abdomen of apterae have prominent, long, thick spines over a tuberculate dorsum; alatae are likewise armed with much shorter and less conspicuous spine-like hairs. The forewings have normal venation with a 3-branched media vein and the branches of the cubitus separated at the base. The abdomen of the aptera bears small indistinct or large paired rectangular patches on each tergites; on alatae each tergite has a small median dorsal pigmented patch on each side. Lateral sclerites are also present. The siphunculi are short, smooth, and without setae; they are somewhat flared apically, but have no apical flange. The cauda is knobbed and the anal plate is weakly bilobed.

Hoplochaitophorus feed on various Nearctic oak (Quercus) species. Where known, they live on the leaves in dense colonies. Oviparae and males develop in autumn. Granovsky (1933) suggested that the genus was probably more closely related to the genus Neosymydobius than to Chaitophorus. This was on the basis of the host on which they feed and a number of morphological characters such as antennae, presence of ovipositor in oviparae, and lack of reticulations on the siphunculi.

 

Hoplochaitophorus quercicola (Spiny oakleaf aphid)

Adult apterae of Hoplochaitophorus quercicola (see first picture below) are greenish with complete or interrupted black abdominal cross bars on each segment. The antennal terminal process is more than 0.65 times the length of the base of antennal segment VI (cf. Hoplochaitophorus spiniferus, whose terminal process is less than 0.60 times the base of that segment). The longest hairs on antennal segment III are 1.0-1.25 times the basal diameter of that segment (cf. Hoplochaitophorus heterotrichus, which has the longest hairs on that segment long and fine, at least twice its basal diameter). The apical rostral segment (RIV+V) is shorter than the second hind tarsal segment (HTII). The pronotum has a group of marginal hairs on each side (cf. Hoplochaitophorus dicksoni, in which the pronotum only has one marginal hair on each side). Most dorsal body hairs are spine-like and are on tuberculate bases (cf. Hoplochaitophorus heterotrichus, in which spine-like dorsal hairs are outnumbered by fine hairs with finely-pointed apices - sometimes there are no spine-like hairs). The siphunculi are flared apically (cf. Hoplochaitophorus spiniferus, which has the siphunculi only slightly flared). The cauda is knobbed, and the anal plate is bi-lobed. The body length of adult Hoplochaitophorus quercicola apterae is 1.8-2.1 mm. Immatures (see second picture below) have less well developed dorsal markings, and tend to have some reddish-brown shading around the markings.

Images above by permission, copyright Claude Pilon, all rights reserved.

Hoplochaitophorus quercicola alatae have dusky forewings with dark-bordered veins.

Hoplochaitophorus quercicola is found on several oak (Quercus) spp. especially white oak (Quercus alba), bur oak (Quercus macrocarpa) and chestnut oak (Quercus prinus). They live in dense colonies along the leaf veins, both on the leaf undersides (Monell 1879) and uppersides (Granovsky, 1933). Oviparae with long, drawn-out ovipositors, and apterous males develop in autumn. The spiny oak leaf aphid is found in the United States (except the north-west) and Canada.

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Acknowledgements

We have used the keys and species accounts of Granovsky (1933) and Foottit & Richards (1993), 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 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

  • Foottit, R.G. & Richards, W.R. (1993). The Insects and Arachnids of Canada. Part 22. The Genera of the Aphids of Canada (Homoptera: Aphidoidea and Phylloxeroidea). Research Branch, Agriculture Canada. Publication 1885. 766 pp. Full text

  • Granovsky, A.A. (1933). Two new genera and species of Aphiidae (Homoptera). Proceedings of the Entomological Society of Washington 35 (3), 29-43. Full text