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Aphidinae : Macrosiphini : Semiaphis horvathi
 

 

Semiaphis horvathi

Short-cornicled hogs-fennel aphid

On this page: Identification & Distribution Other aphids on the same host

Identification & Distribution

Adult apterae of Semiaphis horvathi (see first picture below) are brown (or greenish if our identification is correct) with a grey head and waxy bloom. Their antennae are somewhat less than 0.5 times the body length, with a terminal process that is 1.6-2.5 times as long as the base of antennal segment VI. The apical rostral segment (RIV+V) is 0.7-1.0 times the as long as the second hind tarsal segment (cf. Semiaphis cervariae, which has RIV+V only 0.5-0.6 times HTII). There are well-developed flat marginal tubercles usually present on the prothorax and abdominal tergites I-V, mostly much larger than spiracular apertures, and spinal tubercles usually present on abdominal tergites V-VII. The siphunculi are flangeless, and curved towards the midline; they are less than 0.6 times the cauda, but more than 0.8 times as long as their basal widths (cf. Semiaphis cervariae, which has siphunculi very short and broad-based, 0.4-0.6 times as long as their basal widths). The body length of adult Semiaphis horvathi apterae is 1.6-2.0 mm.

Note: The specimens shown here were identified as Semiaphis horvathi on the basis of the length and shape of the siphunculi (short, flangeless, curved towards midline), and the ratio of terminal process/base of segment VI (for these specimens about 2.2). The colour when alive (dark green) does not agree with the original description ('brown'), but that may have referred to the colour after preservation. It is the only Semiaphis species so far known from Peucedanum officinale.

Images above by permission, copyright Marko Šćiban, all rights reserved.

The alatae are described as brown, with small light brown marginal sclerites. There are 21-28 secondary rhinaria on antennal segment III, 4-8 on segment IV and 1-2 on segment V. The antennal terminal process is 2.6-3.0 times the base of antennal segment VI. Spinal tubercles are somewhat raised, and occur irregularly on abdominal tergites V-VII.

First image above by permission, copyright Zoran Gavrilović, all rights reserved.
Second image above, copyright Krzysztof Ziarnek under a Creative Commons 4.0 licence.

Semiaphis horvathi is believed to be monoecious holocyclic. It has so far been recorded from two genera of Apiaceae, namely Peucedanum and Ferula species. The aphids live in small colonies. The shoot tips of the plant are compressed and the leaves are deformed. Semiaphis horvathi is known from Eastern Europe (Czech Republic, Hungary, and now Serbia), and central Asia (Kazakhstan, Russia).

 

Other aphids on the same host

Semiaphis horvathi has been recorded from 4 Peucedanum species (Peucedanum alsaticum, Peucedanum cervaria, Peucedanum morisonii, Peucedanum officinale).

Semiaphis horvathi has been recorded from 4 Ferula species (Ferula dissecta, Ferula leiophylla, Ferula songarica, Ferula varia).

Acknowledgements

We are grateful to Marko Šćiban, and Zoran Gavrilović for permitting us to reproduce their images of Semiaphis horvathi.

We have made provisional identifications from high resolution photos of living specimens, along with host plant identity. We have used the species account of Szelegiewicz (1967), together with information from Roger Blackman & Victor Eastop in Aphids on Worlds Plants. We fully acknowledge these authors (see references below) 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).

Useful weblinks

References

  • Szelegiewicz, H. (1967). Neue Blattlaus-Arten (Homoptera: Aphididae) aus ungarn. Acta Zoologica Academiae Scientiarum Hungaricae 13 (3-4), 433-444. (p. 433)