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Sanbornia [Aphidini]The Sanbornia aptera has (usually) 4-segmented antennae, and a prominent mushroom-like projection on the vertex. The alate has 5-segmented antennae, with round secondary rhinaria on antennal segments III-V. The fore wings have the media vein once branched, and the hind wings have only the media present. The abdomen of the aptera has unusual humpback shape with a tubercle at the highest point. Marginal abdominal tubercles are absent. Tarsal segment I is minute, without hairs. The siphunculi are reduced to pores, and the cauda is elongate and tapering. There is only one species in the genus Sanbornia. Sanbornia are monoecious holocyclic on juniper (Juniperus). This is a North American genus, although they are now also found in South America (Brazil). Sanbornia juniperi (Humpback juniper aphid) USA, Canada, BrazilAdult apterae of Sanbornia juniperi (see first picture below) are an unusual humpback-shape with a tubercle at the highest point. They are coloured green, with a dorsal coat of flaky, transparent wax. Their antennae are usually 4-segmented (cf. Siphonatrophia cupressi, which have 5- or 6-segmented antennae). The antennal terminal process is more than 0.5 times the base of antennal segment VI (cf. Gootiella tremulae which has the terminal process less than 0.25 times the length of segment VI). The antennal tubercles are well developed, and the frons has a median quadrate (=cubical) projection. The siphunculi are reduced to minute pores hardly larger than spiracles (cf. Siphonatrophia cupressi, which has siphunculi as small, pale cones). The cauda is long and tapering, with more than 20 hairs (cf. Siphonatrophia cupressi, which has a tongue-shaped cauda with about 10 hairs). In slide mounts the cauda of both apterae and alatae appear dusky or dark, so the pale appearance in the live aptera shown below presumably results from a coating of wax. The body length of adult Sanbornia juniperi apterae is 1.2-1.4 mm.
Both images above by permission, copyright Claude Pilon, all rights reserved. Alatae of Sanbornia juniperi (see second picture above) have a pale brownish-green head and thorax, a green abdomen, mainly dark antennae and dusky legs and cauda. Immatures are green, although developing alatae have dark wing buds. Sanbornia juniperi feeds on native American junipers (Juniperus scopularum, Juniperus virginiana), as well as on Juniperus chinensis and possibly on Cupressus. There is no host alternation. The unusual shape of the apterae appears to be cryptic, mimicking the juniper leaf scales (see second picture above). In USA oviparae and alate males occur in October-November. Trioxys cupressicola may be a specialized parasitoid. Sanbornia juniperi is found in the USA and Canada and also in Brazil, the latter possibly as an introduction on imported juniper trees.
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