Report on two African mealybug species (Hemiptera: Sternorrhyncha Coccomorpha)
Author
Williams, D. J.
Author
Matile-Ferrero, D.
text
Zootaxa
2020
2020-03-12
4750
3
439
440
journal article
10.11646/zootaxa.4750.3.11
48538d4e-ef4b-40ef-bff3-e01a344cce31
3707450
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.