Revision of the Bicyclus ignobilis species-group (Lepidoptera: Nymphalidae: Satyrinae) with descriptions of two new species
Author
Brattström, Oskar
Author
Aduse-Poku, Kwaku
Author
Collins, Steve C.
Author
Brakefield, Paul M.
text
Zootaxa
2015
4018
1
57
79
journal article
10.11646/zootaxa.4018.1.3
f419affc-926c-4c76-b8ee-568f0891c0b0
1175-5326
289462
1D7114C5-225C-403E-9F08-F28B5E1E6571
Bicyclus ignobilis
Butler
stat. rev.
(
Figs. 2–6
,
27–28
,
32–33
)
Mycalesis ignobilis
Butler 1870
(
Gold Coast
=
Ghana
)
Bicyclus ignobilis eurini
Condamin & Fox 1963
(Lolodorf,
Cameroon
)
syn. nov.
Bicyclus ignobilis acutus
Condamin 1965b
(Bwamba Forest,
Uganda
)
syn. nov.
Material examined.
Type
material:
Holotype
(
ignobilis
) ♀:
Gold Coast
(
Ghana
),
No further data,
BMNH
(E) #1054538 (
BMNH
).
Holotype
(
acutus
) ♂:
Uganda
,
Buamba Forest (
0°49’N
,
30°04’E
), Sem[u]liki Valley,
2,300– 2,800 ft
.,
3–7.xi.1911
, S.A. Neave leg., No. Rh. 18232 (
BMNH
). Allotype (
acutus
) ♀:
Uganda
,
Budongo Forest (
1°45’N
,
31°25’E
), Unyoro,
3,400 ft
.,
11–15.xii.1911
, S.A. Neave leg., No. Rh. 18233 (
BMNH
).
Non-type material.
276 ♂
& 453 ♀. See Supplementary
Table 1
.
Diagnosis.
Both sexes of
B. ignobilis
usually lack an eyespot in space 3 on the ventral hindwing (
Figs. 2–4
,
32–33
), while all other species in the
ignobilis-
group generally have this spot fully developed. However, there is variation in this trait and occasional specimens of
B. ignobilis
may have a fully developed eyespot. Nevertheless it is a useful initial diagnostic tool before looking at more subtle characters, but not something to alone rely on for identification. The male can be identified by the presence of an extended comb of short shiny black hairs extending from space 1c, in a direction towards the tornal point of the wing and partly covering a prominently enlarged section of vein 1b. The vein is enlarged for about one half to two-thirds of its total length starting from near the base of the wing, and the enlarged section is covered with modified beige scales clearly standing out from the darker colour of the wing (
Fig. 6
). There are no traces of androconial structures on the dorsal forewing. The female is harder to identify in cases where the eyespot in space 3 on the ventral hindwing is not missing, but in general the shape of the forewing apical band should be sufficient. Specimens from the eastern part of the range (
Fig. 33
) have vein 4 more heavily marked in dark, almost breaking up the apical patch in a similar way as in
B. maesseni
(
Fig. 31
) (see section on female identification below). However, the species are only co-occurring in West Africa, where
B. ignobilis
generally have a more solid apical patch (
Fig. 32
). It is therefore a quite reliable identification cue in the areas where the two species occur sympatrically. Across its entire range there is a clinal change in the wing pattern in both sexes of
B. ignobilis
. The main difference is a gradual change in the shape of the ventral hindwing discal band that gets a sharper angle at the distal end of the cell of both wings in an eastwards direction. Another less marked difference is a generally cleaner white and better-developed apical band in males from further east, western males tend to have faintly marked yellow white patch (
Fig. 3
). In addition, as stated above, the female band is often a little more broken up by vein
4 in
the eastern parts of the range.
Supression of subspecific taxa.
The rather strong geographic variation in the species was the basis for the descriptions of two additional subspecies. Specimens from between
Liberia
and western
Nigeria
were assigned to the nominate subspecies (
Type
locality:
Ghana
), while the name
B. ignobilis eurini
Condamin & Fox 1963
was assigned to specimens between eastern
Nigeria
and
DRC
(
Type
locality: Lolodorf,
Cameroon
). The populations found in the extreme east of the range, mainly
Uganda
and
Tanzania
, were assigned the name
B. ignobilis acutus
Condamin 1965b
(
Type
locality: Bwamba Forest,
Uganda
). However,
Condamin (1973)
later suggested that this difference might indeed be clinal, and it is likely that he saw more material of an intermediate morphology in the time between describing the subspecies in the first place up until writing his 1973 monograph. After investigating over
700 specimens
from across the entire range of the species, without finding any area where a sharp transition between the previously described subspecies takes place, we hereby suppress
eurini
and
acutus
as valid names and consider
B. ignobilis
as a single taxon with a marked clinal variation.
Distribution
. The species is distributed between
Sierra Leone
and Central
Uganda
, reaching the Lake Victoria forests in Eastern
Tanzania
. It extends further south than any other species in the
ignobilis
-group with a small number of records in southern
DRC
(
Fig. 27–28
).
Comments.
The original description of the species (
Butler 1870
) does not mention anything regarding the male morphology, and it is likely that the single female individual in BMNH currently recognised as a
type
(Voucher ID: BMNH(E)1054533) was the only specimen available to Butler. Aurivillius appears to have made the first published description of
B. ignobilis
males. In his report (
Aurivillius 1893
) on material collected by Yngve Sjöstedt in
Cameroon
between
1890 and 1891
, he clearly notes the black haircomb on the hindwing. Sjöstedt was reported to have collected two pairs of the species, and four matching specimens bearing labels with his name are still in the collections of NHRS. The
types
of
Bicyclus ignobilis eurini
were not studied (they are located in the Carnegie Museum in Pittsburgh,
USA
). However, the original publication (
Condamin & Fox 1963
) has detailed photos of the
holotype
and allotype, and describes the main morphological characters in extensive detail. We did investigate several specimens from the same general location in
Cameroon
(Supplementary table 1).