i6i 



THE GEOGRAPHICAL DISTRIBUTION OF THE 

 MOTHS OF THE SUBFAMILY BISTONINAE. 



J. \V. HESLOP HARRISON. M.Sc. 



VIII.— THE GENUS ZAMACRA (MEYRICK). 



Zamacra. 



Sub-genus Acanthocampa (Dyar.). Species with two pairs 

 of spurs on the posterior tibiae. 



Acanthocampa excavata (Dyar.). Distribution '.—Japan. 



Acanthocampa diaphanaria (Piing.). N. Persia. 



Sub-genus Zamacra (Meyrick). Species with one pair of 

 spurs on the posterior tibia?. 



Zamacra flabellaria (Heeg.). N. W. Africa, Greece and its 

 islands, Sardinia, Sicily, Asia Minor, Cyprus, Syria, Armenia 

 and Mesopotamia. 



Zamacra marocana (Dognin). Morocco. 



Zamacra juglansiaria (Graes.). Ussuri district and Japan. 



Zamacra okamotonis (Mats.). Japan. 



Of lepidopterous freaks, Zamacra is one of the strangest, 

 with its huge plumose antennas, its curious narrow triangular 

 wings and the reduced genitalia in both sexes ; and these 

 latter unique features mask its affinities and cause great 

 difficulty in assigning it to its correct position. In spite of 

 its anomalies, careful study shows that everything in its 

 structure is purely Bistonine, and its genitalia, when analysed 

 point by point, only serve to emphasise this. 



To determine its point of attachment to the main Bistonine 

 line is still, however, a difficult problem. Its plumose male 

 antennas indicate that it originated early, as this character 

 seems to differentiate Bistonine forms developed in early Pliocene 

 (or possibly late Miocene times) ; whilst the existence of species 

 within its limits provided with the full complement of two 

 pairs of spurs on the posterior tibiae shows that it is a transition 

 genus evolved just when the Non-Boarmioid forms were in 

 the making. Again, its peculiar half-developed wings suggest 

 that it arose at a time when the first wingless mutations 

 occurred, and when this feature was not sexlinked but was 

 passed on in a manner showing blending inheritance. But 

 this combination of plumose antennae, double-spurred tibiae, 

 and incipient female apterousness was only possible at some 

 point between the evolution of Megabiston and Phigalia — and 

 appealing to its larva for indications — we find that its larva 

 is spined or humped ; thus its origin is thrown near to that of 

 Phigalia. Now both Megabiston and Phigalia, as their 

 distribution, particularly that of the former, proves, are of 

 North-eastern Asiatic origin. From this, it is clear that Zam- 

 acra was cradled in the same area ; and this is rendered the 



1917 May 1. 



