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Snowberry aphidsOn this page: Aphthargelia rumbleboredomia symphoricarpi
Adult apterae of Aphthargelia have a mostly dark, sclerotized, and reticulated dorsum. The antennae are without secondary rhinaria and only the apical portions of segments III-V and all of segment VI are pigmented. The femora and tibiae are dark apically, and the tarsi are dark. Chaetotaxy (=bristle arrangement) of tarsal segment I is 3,3,3 (fore, mid, hind). There are marginal tubercles, often very large, on the thoracic segments and abdominal segments II-VI. The siphunculi are dark pigmented, about as long as or shorter than cauda, with the apical half or more usually clavate (=club-shaped). The cauda is pigmented or pale, with 10-20 hairs (rarely < 10) arranged haphazardly.
Alatae have dark dorsal bands and blotches on abdomen that are faintly reticulated. The head, thorax, legs, and siphunculi are mostly dark. Antennal segments III-V have secondary rhinaria, mostly restricted to one side of each segment.
Aphthargelia rumbleboredomia (Rumble's snowberry aphid) Northwestern USA (& possibly Canada)
Apterous viviparae of Aphthargelia rumbleboredomia (see pictures below) have distinctive red, black and orange colouration (cf. Aphthargelia symphoricarpi, the adults of which are black or dusky green). There is a transverse broad white wax band broken in middle by black on tergite I; tergite V has a white wax spot in middle, there is a narrow white wax band just anterior to the siphunculi, and tergites VII, VIII, and the cauda are dusted lightly with white wax. The head is black, red or orange, often paler than the black or reddish thorax. The antennae have segments II-V mostly white, with dark apices, and segments I and VI are dusky or dark. The antennal tubercles are moderately prominent, distinctly exceeding the middle of the frons. The rostrum extends almost to the hind coxae, with the apical rostral segment 0.77-0.92 times as long as the second hind tarsal segment. The thorax is partially covered with a dark shield. The prothorax has marginal tubercles, sometimes very large and/or split into two separate tubercles. Strong marginal tubercles are present on segments II-V and immediately anterior to the siphunculi. The underlying body colour of the abdomen is pale milky yellowish. The abdominal dorsum has a dark reticulated shield restricted to tergites III-V, connected by a narrow spinal band to the thoracic shield (cf. Aphthargelia symphoricarpi, which has a large dark reticulated shield and/or bands on all terga). The siphunculi have dark red internal pigment surrounding their bases. The legs are mostly pale. The cauda is pale and more or less triangular, with 7-17 hairs.
Images above copyright Andrew Jensen under a Creative Commons License.
The alate Aphthargelia rumbleboredomia (not pictured) has 55-77 secondary rhinaria on antennal segment III, 25-61 rhinaria on IV and 0-15 of them on V. The antennal tubercles are moderately prominent, and the rostrum extends to the middle of the mesothorax. The abdominal tergum has dark lateral sclerites. There are intersegmental muscle attachment plates, and partial bands on tergites II-IV, a narrow transverse band between the siphunculi and complete transverse bands on VII and VIII. The siphunculi are dark, and the cauda is more or less triangular.
Aphthargelia rumbleboredomia host alternates between snowberry (Symphoricarpos) as its primary host, and knotweed Aconogonon (= Koenigia) (Polygonaceae) as its secondary host. The species is holocyclic, with oviparae found on Symphoricarpos in September. The aphid has so far been found in Idaho, Oregon, and Washington in USA, but is likely to occur in other U.S. states and some Canadian provinces.
Aphthargelia symphoricarpi (Snowberry aphid) Western & Central USA, Canada
Adult apterae of Aphthargelia symphoricarpi (see first picture below) are black or dusky green (cf. Aphthargelia rumbleboredomia, which has red/orange coloration on the dorsum, especially around the siphunculi and laterally). There are variably developed powdery white wax bands on the head, thorax and abdominal tergites. The most common form is cross bands on abdominal tergites I, IV, V and VIII, but they vary from being almost entirely black, to having to cross bands on all tergites (for the latter see second picture below). There is also a partial or complete spinal wax band from the cauda to the prothorax, where it is broadest, as well as marginal wax bands. The antennae have segments I and VI dark, segment II dusky, segments III-IV pale, and segment V pale with a dark apex. The antennal tubercles are moderately prominent, distinctly exceeding the middle of the frons. The rostrum extends almost to the hind coxae. The prothorax has marginal tubercles, sometimes very large and/or split into two separate tubercles. The abdominal dorsum has a large dark reticulated shield and/or bands on all terga, sometimes narrowed on abdominal tergum II and/or broken in the middle on posterior segments (cf. Aphthargelia rumbleboredomia, which has much reduced dorsal pigmentation on tergites V-VII). Strong marginal tubercles are present on abdominal segments II-V and immediately anterior to the siphunculi. The appendages are mostly pale, the siphunculi and anal plate are black and the cauda is dusky. The siphunculi are imbricated, and often slightly swollen. The cauda is more or less triangular, with 6-19 hairs (rarely less than 10).
First image above copyright Andrew Jensen, second image copyright Jason Headley,
The alate (not pictured) has most of the body, legs, and antennae dark bluish-grey, usually without wax. The abdominal tergum has dark lateral sclerites, intersegmental muscle attachment plates, and various blotches or bands on tergites II-VIII. Between the siphunculi there is a transverse band connected to sclerites surrounding bases of siphunculi and about equal in thickness to the bands/blotches on tergites II-IV. The siphunculi are dark. The cauda is more or less triangular, with 12-20 hairs.
Aphthargelia symphoricarpi feeds on the twigs of snowberry, especially Western snowberry (Symphoricarpos occidentalis) and round-leaved snowberry (Symphoricarpos rotundifolia). Feeding by the aphids results in curling of the leaves. The species is monoecious holocyclic, although males may appear throughout the life cycle (see Jensen in aphidtrek) - this phenomenon is observed in some other species, such as Nasonovia cynosbati. Aphthargelia symphoricarpi is found in western and central USA and Canada.