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Aphidinae : Macrosiphini : Macrosiphum clydesmithi
 

 

Macrosiphum clydesmithi

Slender-cornicled oceanspray-fern aphid

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

Identification & Distribution

Adult apterous viviparae of Macrosiphum clydesmithi (see first three pictures below) are light green, with pale, or sometimes dusky-tipped, siphunculi. The antennae are longer than the body, and are pale with the apices to antennal segments III-V, and all of segment VI, dusky (cf. Macrosiphum rhamni on Pteridium, which has the apices very distinctly black). Antennal segment V is shorter than III (cf. Macrosiphum holodisci on Holodiscus which has segment V usually longer than III). Antennal segment III bears 0-17 secondary rhinaria, which are sometimes scattered beyond its mid-segment. The ultimate rostral segment (RIV+V) is 1.28-2.00 times the length of the second hind tarsal segment and bears 4-7 hairs. The head and tergites VII and VIII often have 1 or 2 spinal tubercles. The abdominal dorsum is entirely sclerotic, pale, and often heavily wrinkled. The dorsal abdominal hairs are much shorter than the basal width of antennal segment III, and are thick and capitate (cf. Macrosiphum osmaronia and Macrosiphum pteridis on Pteridium, which have longer, thin and only faintly capitate dorsal hairs) The siphunculi are very thin; usually they have no reticulations, but sometimes have 1 or 2 indistinct rows (cf. Macrosiphum pteridis, which have rather thick, robust siphunculi, with reticulations always present, usually consisting of several rows). The cauda has 6-8 hairs. Body length of adult Macrosiphum clydesmithi apterae is 1.70-2.96 mm.

Images above copyright Andrew Jensen, under a creative common licence.

Alate Macrosiphum clydesmithi are similarly coloured to the apterous viviparae except for the brownish thorax. Antennal segment III bears 16-53 secondary rhinaria, with rarely one rhinarium on segment IV.

Image above copyright Andrew Jensen, under a creative common licence.

Macrosiphum clydesmithi host alternates from its primary host, ocean spray (Holodiscus spp.) to its secondary host, bracken fern (Pteridium aquilinum). On bracken it is most often found in exposed sites such as open fields and roadsides, as well as rocky outcrops on the edges of mountains and cliffs. The species is holocyclic with mating occurring on the last remaining leaves on Holodiscus late in the year in October-November. The picture above show the ovipara of Macrosiphum clydesmithi. The species occurs in western North America, from Mexico to Washington.

 

Other aphids on the same host

Primary hosts

Macrosiphum clydesmithi has been recorded from 2 Holodiscus species (Holodiscus discolor, Holodiscus dumosus).

Secondary host

Macrosiphum clydesmithi has been reported on one Pteridium species (Pteridium aquilinum).

Acknowledgements

We are grateful to Andrew Jensen for making his images of Macrosiphum clydesmithi available for use under a creative commons licence.

We have used the species accounts given by Robinson (1980) and Jensen & Holman (2000), 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 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

  • Jensen, A.S. & Holman, J. (2000). Macrosiphum on ferns: taxonomy, biology and evolution, including the description of three new species (Hemiptera: Aphididae). Systematic Entomology 25, 339-372. Abstract

  • Robinson, A.G. (1980). A key to Macrosiphum (Sitobion) spp. (Homoptera: Aphididae) on ferns in North America, with descriptions of four new species. Canadian Entomologist 112, 955-961. Abstract