9 August 2024

The Atrophaneura alcinous mansonensis (Fruhstorfer, 1901) – Chinese Windmill had long been listed in the Hong Kong Butterfly List. Recently, many enthusiasts had recognised Byasa confusus (Fruhstorfer, 1901) as the only recognised species for Hong Kong.

To clear up the confusion, we conducted a survey at HKLS to verify the validity of this species.
A. alcinous had been recorded on various peaks in Hong Kong, namely Mt Baker, Mt Nicholson, Victoria Peak and the peaks on Lantau Island. The butterfly was described in detail in Bascombe et al’s book – The Butterflies of Hong Kong, including a drawing of the genitalia. For our exercise, we had obtained two specimens, one from Dr B on the race of Mt Baker from Hong Kong and one from a dealer in mainland China. The results can be seen in the following pictures.

The genitalia of the Hong Kong race match those of Byasa confusus mansonensis (Fruhstorfer, 1901) as illustrated by Dr Bozano in his book – Guide to the Butterflies of the Palearctic Region as well as in the drawing by Bascombe. While the genitalia of the mainland race indicate a different species, which is clearly distinguished by the characteristics in the harpe of the valva. In short, we concluded that the A. a. mansonensis previously recorded in Hong Kong should be treated as B. c. mansonensis.
The mainland specimen, which is easily obtainable, as well as live immatures, should therefore not be lightly considered as B. confusus and should never be released in Hong Kong.