Bicyclus maesseni Condamin

Brattström, Oskar, Aduse-Poku, Kwaku, Collins, Steve C. & Brakefield, Paul M., 2015, Revision of the Bicyclus ignobilis species-group (Lepidoptera: Nymphalidae: Satyrinae) with descriptions of two new species, Zootaxa 4018 (1), pp. 57-79 : 65-68

Bicyclus maesseni Condamin

( Figs. 11–14 , 27 , 31 )

Bicyclus maesseni Condamin 1971 (Lipke Mate, Ghana)

Material studied. 79 ♂ & 127 ♀. See Supplementary Table 1.

Diagnosis. The male ( Fig. 11 ) has two well defined androconial structures (apart from the normal brush in the hindwing cellular area) that set it apart from the other species in the group ( Fig. 14 ). Just as in B. ignobilis a part of vein 1b on the dorsal hindwing is enlarged, but in B. maesseni the enlarged part is much shorter and wider, forming a distinctive bulge close to the base of the wing. There are no long black hairs covering this structure (as found in B. ignobilis ). There is also a quite distinct androconial structure located basally in space 1b, immediately above vein 1, on the dorsal forewing. It is formed by a patch of scales being slightly lighter than the dark base colour, and the basal part of the patch is covered by a loose collection of short hairs. Both sexes ( Figs. 11–12 ) also stand out from similar sympatric species by the heavily darkened veins crossing through the apical patch on the forewing, breaking the patch up in at least two or more separate light subunits.

Distribution. West Africa between Sierra Leone and western Nigeria ( Fig. 27 ). This species was previously thought to occur mainly in the Volta region in Ghana and in eastern Ivory Coast. However, a range of new records has recently been acquired from Liberia and Sierra Leone, as well as many more sites in Ghana, often in sympatry with B. ignobilis . Despite all of these new records B. maesseni is still the only representative of the group in the forests of the Volta region, where it can be reasonably common in the wetter areas. There is also a single specimen from Okomu in western Nigeria, collected by J. Wojtusiak in 1986 and kept in the MZUJ collections (T. Larsen & T. Pyrcz Personal Communication). We have investigated detailed photos of this specimen and it is clearly a male of B. maesseni . At first this might appear improbable, but in reality most species that are found in Volta also extend their distribution eastwards across the Dahomey gap into Western Nigeria and often further onwards to the east ( Larsen 2005). This suggests that the gap opened up well after most current western rainforest species was already dispersed on both sides of its current borders. It is therefore not impossible that the Okomu specimen is a representative from a small relict population in Western Nigeria. Okomu is one of the better-surveyed parts of this area so it is surprising that no other specimens have been previously found, but B. maesseni might just be incredibly rare east of the Volta region. As most forests in western Nigeria are now lost we might not be able to ever know if the species perhaps used to be more widespread until very recently.

Comments. We did not investigate the type material that is kept in MNHN, but the images in the original description ( Condamin 1971) are very clear, leaving no doubt about the morphological characters defining the species.

Figures

FIGURES 11 – 14. Bicyclus maesseni Condamin 1971. 11. Male, Ghana (OB – TER – 0067). 12. Female, Ghana (ABRI – 14 – 354). 13. Male genitalia, Ghana (OB – TER – 0067). 14. Androconial structures (OB – TER – 0067): There is a patch of androconial scales in the basal parts of space 1 b on the dorsal forewing covered by a loose comb of black hairs (encircled in white). The basal parts of vein 1 b on dorsal hindwing are enlarged into a small lightly coloured bulb, and this part of the vein is not covered by any long dark hairs. The enlarged part of the vein is shorter, but wider, than in B. ignobilis and usually very conspicuous (encircled in white). The basal parts of the hindwing cell-brush is also visible in the image.

FIGURES 27 – 29. Distribution maps for the Bicyclus ignobilis species-group. Records of different species from the same site have been slightly offset when presented in the same map so that all species symbols can be clearly seen. Multiple records close to each other have been collapsed to a single point. The complete distributional data is available in Supplementary Table 1. 27 – 28. B. ignobilis (Open Squares) and B. maesseni (Open Crosses). 27. West Africa up to the Cameroonian border. 28. Cameroonian border and eastwards. 29. Remaining species occurring between Nigeria and Eastern DRC: B. brakefieldi (Filled Circles). B. ottossoni (Filled Crosses). B. rileyi (Open Circles). B. vandeweghei (Filled Diamonds).

FIGURES 30 – 36. Identification of females from the ignobilis- group. The images are not shown to scale, arrows indicate the main characters of importance for identification. 30. B. rileyi is much larger than any other species and the light markings in the apical patch continue below the eyespot in space 2, and often reach the lower margin of the wing. 31. B. maesseni has the edge of the apical patch more broken up in the area closest to the apical eyespot. Also, vein 4 is heavily marked with darker scales, breaking up the patch along its entire length. 32. B. ignobilis (western part of range) almost always lack the ventral hindwing spot in space 3, the apical patch is also much more solid than in B. maesseni with vein 4 just making a dark indentation in the basal part of the light patch. 33. B. ignobilis (eastern part of range) has vein 4 more heavily darkened so that the apical patch is sometimes fully broken up in sections. This makes them appear similar to B. maesseni, but the latter species is not sympatric in the eastern part of the range of B. ignobilis. The ventral discal band gradually gets a more pronounced edge at the end of the cell on both wings in a clinal fashion towards the east of the species range. 34. In B. ottossoni the basal part of the apical patch lacks indentations of dark scales along vein 4. The outer borders of the patch are much better defined than in the other species. The distal margin of the forewing is also much less convex, giving the wing a more squared shape. 35. B. vandeweghei have much more prominent light shading around the hindwing eyespots. The apical patch is otherwise similar to B. ignobilis. 36. B. brakefieldi have a more yellowish colour in the apical patch, and the part of the patch being placed basally of the eyespot is a bit fainter than in other species.