528 Rev. K, St. Aubyn Rogers' Bionomic Notes on 



The relation of the eastern and western sub-species of 

 Fscudacrwa hoisduvali to tlieir respective Acroeine models 

 is interesting and peculiar. There can be no doubt that 

 the eastern sub-species trimenii with its conspicuous sub- 

 apical yellow-ochreous fore-wing bar, mimics Acriea acara 

 (in Avhich the apical portion of the fore-wing is warm red- 

 dish-ochre), and bears no very close resemblance to areca or 

 to any of the other large red black-marked eastern Acrseas, 

 The western hoisduvali, on the other hand, is a much 

 closer mimic of Acrxa egina, the western representative of 

 areca, than it is of zetes, the representative of the eastern 

 model of trimenii. This is all the more remarkable because 

 zetes is replaced by acara in the Cameroons, as I was 

 astonished to find in the collection of the Brussels Museum. 



This mimetic relationship is unusual, and is all the 

 more remarkable because the eastern mimic is transitional 

 into the western, the eastern model into the western zetes, 

 the western model into the eastern egina. It is probable 

 that this curious relationship is to be explained by the 

 fact that acara is, on the whole, predominant over areca 

 in the range of trimenii, and egina (the W. representative 

 of areca) predominant over zetes (the W. representative of 

 acara) in the range of hoisduvali. (Compare Mr. Roland 

 Trimen's account on pp. 552-554.*) 



A very interesting detail in the mimetic resemblance 

 of the Fseudacr/ea is to be seen in the palpi, which are 

 oranffe like those of Acriea acara, A. areca, A. anemosa, 

 and A. natal ica. A parallel case is to be found m the 

 3fciJiona-Thyridia-cenived combination of tropical South 

 America, in which the yellow or orange-clubbed antennae 

 of the models are mimicked by Danainie (Ituna), Pierinie 

 {Dismorphia) and Castniid moths. In both cases the 

 small size of the mimetic feature is probably compensated 

 by its prominence. E. B. P. 



c. Comhination of small fulvous and hlach Acrxas from 

 Wcithaga. 



This group consists entirely of species of the genus 



* Just as Mr. Trimen finds obv^ious links with the western boisdn- 

 vali in the pattern of certain eastern indivichxals, and especially 

 one of the Rubai specimens liere referred to, so also a clear transition 

 towards the eastern trimenii may be seen in Angolan specimens in 

 whicli a trace of the ochreous sub-apical fore-wing bar is present. 

 It is however probable that acavd and not zetes is the Angolan form. 



