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Genus Idiopterus

Fern aphids

On this page: Genus Idiopterus Idiopterus nephrelepidis

Idiopterus [Macrosiphini]

Idiopterus are medium sized aphids with a wrinkled dorsal cuticle with reticulation formed by rows of small spicules. The head is rough with spicules. The antennal tubercles are large, with parallel inner sides with little sign of a median frontal tubercle. The antennae are longer than the body, with secondary rhinaria in both the apterae and alatae. The wings have a pattern of dark pigmentation and unusual venation.

There is only one species in the genus Idiopterus, namely Idiopterus nephrelepidis which feeds on ferns.

 

Idiopterus nephrelepidis (Black fern aphid)

Adult apterae of Idiopterus nephrelepidis are pear-shaped and black, with transverse rows of white flat-topped setae on the dorsal tubercles of the abdomen and thorax. The legs and antennae are pale and translucent, with the antennae ringed with black. The antennal terminal process is 4.5-5.0 times the length of the base of antennal segment VI. The apical rostral segment is about twice as long as the second hind tarsal segment. The siphunculi of apterous Idiopterus nephrelepidis have the basal quarter to a third dark, but distal parts are pale. The siphunculi are about twice the length of the cauda which is black and tongue-shaped with 5 hairs. The body length of the adult aptera is 1.2-1.6 mm.

Both images copyright Dave Appleton, all rights reserved.

The alate viviparous female of Idiopterus nephrelepidis (see second picture above) has dorsal hairs not placed on tubercles, but on small scleroites. Marginal sclerites are present. Antennal segment III has 7-14 secondary rhinaria, segment IV has 1-5, and V has 0-3. The forewing has a large clear spot in the pterostigma and all veins are surrounded by broad black borders. The hind wings are reduced in size.

Idiopterus nephrelepidis feeds on various species of ferns including spleenworts (Asplenium), bracken ferns (Pteridium) and polypodies (Polypodium). Reproduction is entirely parthenogenetic, and no sexual forms have been found. The species is thought to have originated in the neotropics but has since spread over much of the world. In northern temperate regions it is generally thought to be restricted to glasshouses, caves and other sheltered environments - although the chapel ruins from which it is reported here seem rather less sheltered than most previous known habitats.

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Acknowledgements

We are extremely grateful to Dave Appleton for the images of live Idiopterus nephrelepidis, and for making extra visits to the field site to take additional photos. We are also grateful to Dr Jit Thacker for putting us in touch with Dave re the find of Idiopterus.

We have made provisional identifications from high resolution photos of living specimens, along with host plant identity. In the great majority of cases, identifications have been confirmed by microscopic examination of preserved specimens. We have used the keys and species accounts of Blackman & Eastop (1994) and Blackman & Eastop (2006) supplemented with Blackman (1974), Stroyan (1977), Stroyan (1984), Blackman & Eastop (1984), Heie (1980-1995), Dixon & Thieme (2007) and Blackman (2010). We fully acknowledge these authors 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

  • Blackman, R.L. & Eastop, V.F. (2006). Aphids on the world's herbaceous plants and shrubs. Vols 1 and 2. John Wiley & Sons.