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Biology and MorphologyOn this page: Biology Morphology Genera Tribe Eulachnini Tribe Lachnini Tribe Stomaphidini Tribe Tramini Tribe Tuberolachnini
The Lachninae is one of the larger subfamilies with 346 species in 19 genera in 5 tribes (Eulachnini, Lachnini, Stomaphidini, Tramini, Tuberolachnini). No extant species of Lachninae have host alternation, and in the largest tribe, Eulachnini, nearly all species feed on conifers. Because of this it was originally thought that the Lachninae originated before the expansion of angiosperms in the Cretaceous, and hence might occupy a basal position in the aphid phylogenetic tree. Ortiz-Rivas & Martínez-Torres (2010), using symbiont-DNA and other data concluded that the Lachninae was a basal taxon.
However, this finding is disputed partly because all members of the other 4 Lachninae tribes are associated with angiosperms, living all year around on oaks & beeches (Fagaceae) or woody roses (Rosaceae), or on the roots of herbaceous plants. At present, most authorities accept an ancestor of modern Eulachnini living on a woody angiosperm acquired a conifer host secondarily, and this then opened up great opportunities for adaptive radiation on conifers. The Tramini, the tribe of Lachninae now living all year around on roots of Asteraceae or Ranunculaceae, once had ancestors which migrated back to a woody primary host.
Trama troglodytes aptera.
Lachnini have a holarctic distribution, especially the central & eastern Palaearctic. The Eulachnini are also holarctic, but more in the Nearctic than in the Palaearctic. The Tramini have a Palaearctic distribution.
Adult Lachninae viviparae may be apterous or alate. These are mostly large aphids, often strongly pigmented. Their body and appendages densely are covered with either long or short hairs. The eyes are normally large, except in some species on roots of herbs. In most genera the head has a distinct longitudinal mid-dorsal suture, and is not fused with the pronotum. The antennae have 5 or usually 6 segments, and a short terminal process; shorter than the base of antennal segment VI. The rostrum in most genera is long, and segments IV and V are not fused. The dorsal abdomen does not have an extensive solid black patch. Marginal and dorsal tubercles are absent. The first tarsal segment has numerous hairs. Wax glands are unicellular, opening separately into the integument, and are not arranged into facets. The siphunculi are usually pore-shaped, set on low cones or sclerites but, in some Tramini, are completely absent. The cauda is short and broadly rounded with numerous hairs, and the anal plate is entire.
Cinara laricis aptera.
Alatae have the primary rhinaria on their antennae not surrounded by minute hairs. Secondary rhinaria on alatae are circular, subcircular or slightly oval, occasionally present on all segments of the antennal flagellum, and often close to their apices. The media of the fore wing is usually branched, and is usually much thinner and fainter than the other veins. Cubitus branches are close together at the bases. The pterostigma is not very dark and is much longer than wide.
Cinara pini alate.
The Lachninae are one of the larger subfamilies with 346 species in 19 genera in 5 tribes (Eulachnini, Lachnini, Stomaphidini, Tramini, Tuberolachnini).
Genus Cinara [Eulachnini]
Aphids are usually large (apterae up to 5-6 mm in length), and may be winged or wingless. They are frequently wax-powdered and densely haired. The antennae are shorter than half the body length. The rostrum is relatively long reaching to behind the hind coxae. The apical part of the rostrum is slender, pointed and very long, 2-5 times as long as its basal width and is made up of two segments termed RIV and RV. The abdominal dorsum has 6 or more longitudinal rows of small, dark brown intersegmental muscle sclerites. The siphunculi are pore-like and located on broad, often pigmented, hairy cones. The cauda is always broader than long, either rounded or triangular. Males may be wingless or winged depending on species, and oviparae often differ from viviparae in the presence of a perianal ring of wax.
This is a very large genus sometimes assigned to its own subfamily, with species on conifers of the families Pinaceae and Cupressaceae. Many of the species (150) are native to North America, but there are also 55 species found in Europe and Asia. Cinara aphids do not host alternate, but remain on their chosen host species throughout the year. They may feed on the roots, branches, or foliage, and are often attended by ants.
Genus Essigella [Eulachnini]
These are long-bodied aphids, similar to Eulachnus, but smaller and with 5-segmented antennae. The apterae are spindle-shaped, with a tapered abdomen, but the "spindle" is truncated at the head end, which is relatively broad. The claws have modified apices, being bifurcate or double. The abdominal tergites are lightly to heavily sclerotized but not necessarily pigmented.
About 14 North American species, all living on pine (Pinus) needles except for one species on Douglas fir ( Pseudotsuga). They are often overlooked, as they feed near the bases of the need and move quickly when disturbed. Some have now been recorded as invasive species in Europe.
Genus Eulachnus [Eulachnini]
Small, narrow and elongate greenish to olive brown aphids with long limbs. The siphunculi are slightly elevated, rim-like structures, barely visible in this image of an adult apterous Eulachnus. Antennae are 6-jointed.
This genus comprises about 17 species all of which live on the needles of pine (Pinaceae spp.). They are cryptic when feeding, but very active when disturbed. The best-known species show preferences for certain Pinus spp., but none is strictly confined to one species. They have a sexual stage in the life cycle but do not host alternate and are not attended by ants.
Subgenus Schizolachnus [Eulachnini]
Rather small oval-bodied, hairy aphids which may be winged or wingless. The body is grey-green and usually covered with a dense coat of flocculent wax The siphuncular cones are small and pale.
This subgenus includes seven species (four nearctic and three palaearctic) all of which feed on the needles of pine (Pinus). They are found as small densely packed colonies along a needle. Despite the rather different appearance of the aphids, it appears that Schizolachnus is closely related to Eulachnus. They have a sexual stage in the life cycle, but do not host alternate and are not attended by ants.
Genus Lachnus [Lachnini]
Medium to large brown or black long-legged aphids which may be winged or wingless. They usually have prominent siphuncular cones. The cauda and anal plate are rounded. Winged forms have more than half the area of the forewings pigmented and the wings are relatively small, compared with the large body.
This genus includes about 22 species which mainly feed on the twigs and branches of broadleaved trees especially oaks, chestnuts and beeches (Fagaceae). They have a sexual stage in the life cycle but do not host alternate and are nearly always attended by ants.
Longistigma are very large, bark-feeding aphids. Their antennal tubercles are undeveloped. The antennae are 6-segmented with a short terminal process. The rostrum is clearly 5-segmented, but segment V is fused caplike to the apex of segment IV. The forewing has a long stigma, extending around the tip of the forewing. The radial sector is straight, reaching the margin at the wing apex. The siphunculi are short, almost poriform, each on a large subcircular mammiform base and the cauda is short, almost arc-shaped.
There are two Asian species and one North American. Two of these species are known to be polyphagous feeding on the bark of a variety of tree genera.
Image by permission, copyright Claude Pilon, all rights reserved.
Genus Maculolachnus [Lachnini]
Medium-sized aphids, the adult viviparae of which may be winged or wingless. They have no distinct pattern of pigmentation on the forewings but have a black spot at the base of the pterostigma. Dorsal hairs are often placed on dark scleroites. The siphuncular cones are low, hairy and conical.
Three species feeding on members of the rose family (Rosaceae). They have a sexual stage in the life cycle overwintering as eggs, but there is no host alternation. They are attended by ants.
Genus Stomaphis [Stomaphidini]
Stomaphis are large or very large oval aphids which are characterized in the females by a very long rostrum. Their antennae are 6-segmented and densely hairy. Their siphunculi are pores on low, haired, cones. The second segment of the hind tarsus is rather long compared with other lachnids. Males are small, apterous and have no mouthparts.
Stomaphis feed on the stems and roots of a variety of tree species, with most species on oak (Quercus), birch (Betula), maple (Acer), willow (Salix) and poplar (Populus).
Image copyright Julian Hodgson, all rights reserved.
Genus Protrama [Tramini]
Protrama are medium to large aphids. The apterae are normally alatiform, with dark dorsal cross bands and dark siphuncular cones. The eyes are large and the antennae are about half the body length. The hind tarsus is 0.5-0.9 times as long as the hind tibia. Siphuncular cones are present and are low and hairy. The cauda is rounded.
Protrama feed on underground parts of members of the daisy family, Asteraceae, (especially thistles and wormwoods), or of members of the buttercup family, Ranunculaceae. Amongst the Lachnini, members of the genera Protrama and Trama are the only ones that do not have trees as their only host.
Genus Trama [Tramini]
Trama are medium to large aphids. Apterae are whitish and densely hairy, with small compound eyes and no dark dorsal pigmentation. Their antennae are about 0.5 times the body length, with the antennal terminal process less than 0.25 times the base of antennal segment 6. The hind tarsus is greatly elongated. Most of the species (those in the subgenus Neotrama) have siphuncular pores on low cones, but the three species in the nominate subgenus have neither siphunculi nor siphuncular pores. The cauda is rounded.
There are 14 Trama species worldwide, mostly living on the roots of Asteraceae where they are attended by ants.
Genus Tuberolachnus [Tuberolachnini]
Large aphids which may be winged or wingless. They have a single large tubercle on the back of the fourth abdominal tergite (just in front of the siphunculi). Siphunculi on large dark cones. Antennae about half the body length.
A small genus with only three species of aphids, two of which are only found in the Far East (subgenus Tuberolachniella). The remaining species, Tuberolachnus salignus is cosmopolitan, and feeds on willows (Salicaceae). It does not host alternate and does not appear to have a sexual stage in the life cycle. It may be ant attended.