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Aphididae : Aphidinae : Catamergus
 

 

Genus Catamergus

Catamergus aphids

On this page: Catamergus fulvae kickapoo

Catamergus [Macrosiphini]

Catamergus is a small genus of pear-shaped medium-sized aphids. The antennal tubercles are well-developed, and the front of the head is convex. The antennae are 6-segmented, and the terminal process is long without numerous setae. The rostrum is 4-segmented with the apical segment slender and conical. The fore wing of the alate has normal venation; the media vein has 3 branches and the cubital veins are separated basally. The prothorax has marginal tubercles, and abdominal tubercles are present on segments II-VII. The siphunculi are slender, cylindrical, equal to or slightly longer than cauda, without setae, with spiculose and smooth imbrications, and with 1 or 2 subapical rows of reticulations, and a very narrow flange. The cauda is elongate, broadly rounded apically, and the anal plate is entire.

Catamergus aphids are similar to those in genus Macrosiphum. They can be distinguished by their shorter, nearly flangeless siphunculi, the association of Catamergus fulvae with Impatiens, and the reduced number of reticulations on their siphunculi. In Macrosiphum, the siphunculus is much longer than the cauda and has four or more rows of subapical reticulations. In life, Catamergus have a light covering of white wax, which is distinctive, although some species of Macrosiphum, such as Macrosiphum albifrons, are also waxed.

There are only two species in genus Catamergus, one of which feeds on Impatiens spp. and the other on Polygonatum spp.. Both are monoecious holocyclic and are restricted to the Nearctic region. Oestlund (1923)[1922] initially created the genus Catamergus, but a more detailed diagnosis is available from Footit & Richards (1993).

 

Catamergus fulvae (Waxy impatiens aphid)

Adult apterae of Catamergus fulvae are green, with a light dusting of white wax. Their antennae of adults are longer than the body and bear secondary rhinaria on antennal segment III (please note all the apterae in the two pictures below are immatures, which have heavier wax deposits and somewhat shorter antennae). Their antennal tubercles are well developed and divergent. The dorsal abdomen is entirely membranous without any sclerotization, and there are no marginal tubercles on abdominal tergites I and VII. Their siphunculi are rather thin, and about as long as the cauda. The siphunculi have a pale basal half, a dark distal half, and 1-4 rather indistinct rows of polygonal cells near the apex. The body length of adult apterae is 2.3-2.8 mm. Immature apterae (see pictures below) are similar in appearance to adult apterae, but have shorter antennae and cauda.

Both images above by permission, copyright Claude Pilon, all rights reserved.

The alate Catamergus fulvae (see second picture above) has the head and thorax dark green to brown, and the abdomen pale green. Their antennae are longer than the body and more-or-less dusky. The siphunculi are dusky to black, and are about as long as the cauda.

The waxy impatiens aphid is found on the lower parts of Impatiens species. It feeds only on Impatiens and does not host alternate. Oviparae and alate males are produced in September, and the species overwinters as eggs. Catamergus fulvae is found in north-eastern and midwestern USA, and eastern Canada.

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Catamergus kickapoo (Pellucid solomons seal aphid)

Adult apterae of Catamergus kickapoo (see first picture below) are whitish green with dusky brown tips to the femora, tibiae, base and terminal process of antennal segment VI; the tarsi and apices of the siphunculi are dark. The antennal tubercles are well-developed with their inner faces divergent. The median frontal tubercle is not developed, so that head has U- or V-shaped frontal sinus in dorsal view. The siphunculi have a subapical zone of polygonal reticulation with several rows of closed cells; the siphunculi are 0.13-0.19 times the body length and 1.9-2.6 × the length of the second hind tarsal segment (HT II) (cf. Macrosiphum insularis and Macrosiphum euphorbiae, which have siphunculi 0.21-0.35 times the body length and 3.0-6.5 times HT II). The cauda is triangular with 3 hairs on each side. The body length of adult apterae is 1.9-2.2 mm. Immatures (see second picture below) resemble the adult apterae, but with shorter or no cauda, and with entirely pale siphunculi.

Both images above by permission, copyright Claude Pilon, all rights reserved.

Catamergus kickapoo only feeds on the undersides of leaves of Polygonatum species. Their light coloration makes them easy to detect on the lower sides of the green leaves of their host plant. Sexual forms with oviparae and alate males develop in August-September. Catamergus kickapoo is found in eastern USA and Canada.

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Acknowledgements

We have used the keys and species accounts of Oestlund (1923)[1922], 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

  • Oestlund, O.W. (1923)[1922]. A synoptical key to the Aphididae of Minnesota. Report of the State Entomologist of Minnesota 19, 141.