Genus Smynthurodes

Smynthurodes [Fordini]

Smynthurodes are rather small aphids, the apterae of which have two distinctive characteristics: (a) The second segment of the antenna is distinctly longer than the first, being similar in length to the third segment. (b) The primary rhinaria on the last two segments have thick, hairless, sclerotized rims. The alatae have the forewing veins dark-bordered, and the third antennal segment has numerous hairs, most of which are much longer than basal diameter of that segment.

There is only one species in the genus, Smynthurodes betae. It produces small midrib galls (for fundatrix) or larger leaf-edge galls (for her offspring) on Pistacia in the Mediterranean region, and as far east as Pakistan. The parthenogenetic generations feed on the roots of many dicotyledonous plants.

Smynthurodes betae (bean root aphid)

On the primary host (Pistacia), Smynthurodes betae fundatrices induce small red midrib galls, and their offspring induce yellow-green or red spindle-shaped leaf margin galls. On the secondary host (roots of many plants) adult apterae are small to medium-sized, globular in shape, and coloured a dirty yellowish white (see first picture below). They are wax dusted, and clothed with numerous fine hairs. Their immatures are light green (see second picture below). The head, prothorax, antennae and legs are light brown. The antenna are 5-segmented (cf. Trama species which have six antennal segments) and the second antennal segment is elongated and about the same thickness as the third antennal segment. There are thick sclerotized rims on the primary rhinaria of the last two antennal segments. There are no siphunculi (cf. Protrama, Tetraneura and Anoecia species, which have siphunculi). The body length of the adult Smynthurodes betae aptera is 1.6-2.7 mm.

Alates of Smynthurodes betae have dark transverse bars on the abdominal tergites.

Where the primary host (Pistacia) is found, the bean root aphid goes through its full life cycle, host alternating from Pistacia to numerous secondary hosts, especially in the Asteraceae, Fabaceae and Solenaceae. Smynthurodes betae can also persist on its secondary hosts as anholocyclic parthenogenetic populations. It commonly overwinters in ant's nests. Anholocyclic parthenogenetic populations of Smynthurodes betae are found in most countries of the world, except the coldest parts. It goes through its full life cycle in North Africa, Israel, Syria, Iran, southern Crimea, Transcaucasus and Pakistan.

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Acknowledgements Whilst we make every effort to ensure that identifications are correct, we cannot absolutely warranty their accuracy. We have mostly made 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.