Aleyrodes

Gill, Raymond, 2012, A preliminary report on the World species of Bemisia Quaintance and Baker and its congeners (Hemiptera: Aleyrodidae) with a comparative analysis of morphological variation and its role in the recognition of species Raymond Gill, Insecta Mundi 2012 (219), pp. 1-99 : 14-15

Aleyrodes appear most similar to the Bemisia group of species (most specifically the afer group),

although they do not exhibit the development of tubercles or other protuberances. They can be separated by the median width of the 7 th abdominal segment anterior to the vasiform orifice subequal to the width of the other segments, and that in the adults the 4th antennal segment is subequal in length to the 5 th segment. In the afer group, the width of the 7 th abdominal segment is much less than that of the other segments, and the adult antennal segment 4 is shorter than segment 5. Molecular data suggests that Aleyrodes and Bemisia are not closely related.

As suggested by Gill and Brown (2010), Dinsdale et al. (2010) and De Barro et al. (2011), the taxonomic status of B. tabaci is a complex problem, and is possibly a complex of as many as 24 sibling or cryptic species. Whatever the case, there is little morphological evidence to justify separating any of the forms within the tabaci complex, except for B. capitata ( Fig. 15) and possibly the grass feeding form from Sudan ( Fig. 51). If this is true, then there would appear to be a similar situation within the afer complex. The afer complex specimens show a much greater amount of morphological variability than does the tabaci complex, as illustrated here and by Gill and Brown (2010), and this morphology was at one time used to separate species and even genera. But after careful study of the morphological variability, it is apparent that the species and generic limits formerly used in this group of whiteflies are a problem even more complicated than it is in the tabaci complex. Due to the extreme variability in the afer complex, it is probably no longer feasible to try to maintain species or generic limits in this group and other intermediate forms based on morphology alone. The same is true for the tabaci complex, although the amount of morphological variation between populations of B. tabaci is not nearly as great.

The afer complex specimens show a highly variable morphology that is in part affected by host and possibly by other environmental factors. When this variability is studied on a worldwide scope,

not only may species status be suspect, but also that of genera, as suggested by the synonymy of