Pseudococcus bingervillensis Magnin, 1955

Williams, D. J. & Matile-Ferrero, D., 2020, Report on two African mealybug species (Hemiptera: Sternorrhyncha Coccomorpha), Zootaxa 4750 (3), pp. 439-440 : 439-440

Pseudococcus bingervillensis Magnin

When Magnin described this species from IVORY COAST, Bingerville, on Alchornea cordifolia (Euphorbiaceae) ( Magnin 1955), he compared it with Pseudococcus njalensis Laing ( Laing, 1929) , now Formicococcus njalensis (Laing) , a species that has since become well known as a vector of the virus causing swollen shoot disease of cacao ( Hall, 1945, Strickland, 1947). According to Ben-Dov (1994) the type material of P. bingervillensis is probably lost. Magnin showed long dorsal setae on the head including those associated with the cerarii. Laing (1929) described F. njalensis originally from Sierra Leone on coffee but it is now known to occur throughout West Africa on at least 77 plant species in 30 plant families (García-Morales et al. 2019).

Species in the genus Formicococcus Takahashi usually possess 18 pairs of cerarii, four of which occur on the head. Many of the cerarii each possess more than two conical cerarian setae. In an extensive study of the number of cerarii and numbers of cerarian setae on both sides of the body, on specimens from different localities and host plants in West Africa, Hall (1945) found wide variation. On the head and thorax only, the numbers of cerarii varied from 3–7 on one side, with a total of 6–36 conical cerarian setae. Specimens with the lowest counts were from Ashanti, Ghana, on Sterculia setigera (Sterculiaceae) . All the specimens that Hall examined are deposited in The Natural History Museum, London (BMNH). Also listed by Hall (1945) is the host plant Alchornea cordifolia from Ghana, the same plant species as that on which Magnin’s specimens were collected.

Hall (1945) also discussed the wide variation in numbers of setae and their lengths in the Formicococcus specimens he studied. Sometimes the conical cerarian setae are replaced by long flagellate setae, and Ezzat & McConnell (1956) (using the combination Planococcoides njalensis ) stated that sometimes the fine dorsal setae come close enough to the cerarii to be considered as auxiliary setae. In Magnin’s illustration, most of the marginal setae on the head are long and flagellate but there are four cerarii on one side with conical setae.

The Muséum national d’Histoire naturelle, Paris contains many specimens of F. njalensis , including many from Ivory Coast. Among these specimens are the following examples:

1. Côte d’Ivoire, Sakassou , N’Gata, Bois Sacré, on Alchornea cordifolia, C. Richard , 24.xi.1977, MNHN 7275 (4 slides, 3 adult females, 1 nymph) with 5 pairs of cerarii on the head containing conical setae, and a total of conical setae on each side of the body of: 14, 16, 17, 18, 13, 12 .

2. Côte d’Ivoire, Toumodi , Lamto, Yaoble Baca, on Alchornea cordifolia, C. Richard , 2.xi.1977, MNHN 7148 (3 slides, 4 adult females) with 5 pairs of cerarii on the head and thorax containing conical setae and a total of conical setae on each side of the body of: 14, 11, 11, 11, 11, 12, 10 and 10 .

Although the above localities are not close to Bingerville (a suburb of the capital, Abidjan), the data show that there is much variation in the numbers of head cerarii and their conical setae on specimens from the type host plant of Magnin’s species. Also, the characters used to separate P. bingervillensis from F. njalensis in Ivory Coast fall within the range of variation in specimens of F. njalensis from other parts of West Africa. Magnin also separated his new species from F. njalensis because some cerarian and long dorsal setae had bifid tips; however, sometimes these setae become split at the tips during preparation on microscope slides. Magnin also stated that the “pores circulaires” or simple pores on the dorsal margin of his species were fewer than in F. njalensis ; but Hall (1945) had already mentioned that there was some variation in their numbers in the material he had examined. We conclude that the name Pseudococcus bingervillensis Magnin is a junior synonym of Formicococcus njalensis (Laing) syn. n.

We thank Gillian Watson for kindly reading the manuscript and for important comments.