MIMETIC ASSOCIATIONS 



49 



the female A. lycoa is probably synaposematic with the black and white forms of Amauris 

 and Planema, but as we pass eastwards the pattern gradually changes in both sexes, though 

 less rapidly in the male. The spots and hind-wing patch become less indefinite in outline, 

 and much more clearly separated, whilst the latter marking undergoes a change from white 

 to yellow, and the ground-colour becomes much darker. From Sierra Leone down to the 

 French Congo and across the Congo State comparatively httle change is observable, but 

 at Entebbe there is sufficient modification to enable the examples from that locality to be 

 distinguished from the extreme western forms. At Kilimanjaro we have a further develop- 

 ment to the fallax form of Rogenhofer, figured in Plate III. In this the spots are clearly 

 defined in both sexes, but they remain white in the female and pale yellow in the male. 

 The hind-wing patch in both sexes is pale yellow. The insect has become modified so as to 

 resemble the dominant eastern Danaines, Amauris echeria and A. alhimaculata. Up to this 

 point the species is sexually dimorphic, but in the remarkable Abyssinian subspecies, A . lycoa 

 aequalis, R. and J., this character disappears, and we have both sexes alike in coloration. 

 The ground-colour is brownish-black, the hind-margin of the secondaries having, especially 

 in the female, a tendency to a reddish-brown colour. The spots and hind-wing patch are 

 clearly defined, and of a rather deeper yellow than in the other forms. ^ 



In the case of A . johnstoni there is no sign of sexual dimorphism. All the varieties occur 

 in both sexes, nor is there good reason to separate them into geographical subspecies, with 

 the exception of the toruna form. This latter occurs at Toro in Western Uganda and also in 

 the Urundi country between Lake Kivo and Lake Victoria Nyanza, to the north-east of Lake 

 Tanganyika. As the figure on Plate III shows, it is a very perfect mimic of Planema latifas- 

 ciata, Sharpe (also figured on the same plate), which occurs in the same region. In the 

 Tiriki Hills and on Kilimanjaro the commonest form is the confusa of Rogenhofer, a white- 

 or yellow-spotted form very closely resembling lycoa fallax, and mimicking the same Danaine 

 species. Here we find also the typical johnstoni of Godman ( = semifulvescens, Oberth.), some 

 examples of which, having the hind-wing discal area white, instead of yellowish as in the 

 type, show a modification in the direction of Planema poggei. This form is illustrated on 

 Plate VIII, Fig. 13. The form fulvescens, Oberth., Plate III, Fig. 26, has almost lost the 

 spots of the fore-wing and the patch in the secondaries, and is synaposematic with Danaida 

 chrysippus f. dorippus and Acraea encedon f. daira. All the johnstoni forms, except some 

 examples of toruna, have the distal outline of the hind-wing patch somewhat edentate, giving 

 it a quadrate appearance. 



There is in the Tring Museum a family of Acraea johnstoni bred from a batch of ova 

 at Nguelo, Usambara. It consist of nine individuals, comprising two and one ? fulvescens 

 of fairly typical form, one ? fulvescens somewhat intermediate to the type, two and one ? 

 resembling the type form { = semifulvescens), but with the discal patch of the hind- wings 

 whiter, one of the confusa form, spots and hind-wing patch yellow, and one 5 of the confusa 

 form with all the markings white. The causes underlying the development of these 

 polymorphic forms remain somewhat obscure. We can only at present call attention to the 

 fact that of the innumerable patterns which might conceivably be assumed, only those are 

 developed which resemble the appearances of dominant protected forms, and we must await 

 the time when further investigation based on extensive breeding experiments may throw 

 additional light on these complicated associations. 



1 It is interesting to note that the sleeken form entirely devoid of white spots. It is doubtless in 

 of A . echeria occurring in Abyssinia is characterized mimicry of this form that the white spots have dis- 

 by having the markings of a deeper and duller ochreous appeared from the female lycoa aequalis. 

 than in other forms of the same species, whilst it is 

 1200 G 



