Four images of three different butterflies, taken at two sites. Although all these look like dry season forms, all were taken recently toward the end of the wet season. I have various ideas about them, bit nothing really fits.
Image 1 and image 2, taken at Nam Nao, nc Thailand. Upper and under side of the same butterfly. Mycalesis nicotia?
Image 3 from nearby Nam Nao. Mycalesis gotama?
Image 4. From Kaeng Krachan, northern peninsula Thailand. Looks similar to Mycalesis mnasicle, but not right.
Many thanks for the reply. Sorry about the confusion of images 1 and 2 being the same butterfly. Those two photos were taken only a few seconds apart, so I assumed must be the same. Just goes to show how confusing these bushbrowns are!
So what constitutes dry season forms? I have always assumed it would be those adults flying in the dry season. All these images were taken in October, after three months plus into the wet season and still raining with good vegetation. What is the definition of a dry season form please?
In conclusion ;2 is the upperside of M. intermedia.
1 & 4 (likely) are the undersides.
Regarding wsf & dsf .
wsf are typical forms which occur in areas with seasonless climates.
In Malaya in the north border areas with 2-3 months of little rain dsf appear. Melanitis leda dsf appears freguently even in Malaya & Singapore.
In the north subtropical belt dry season also coincide with the cooler winter months & decreased daylight & these two factors are stated to be also responsible for some forms of dsf.
Photoperiodism (daylight > or < than 12 hrs.) ,affects mainly Pierids eg Appias, Cepora & Captopsilia.
Temperature ,ie spring & summer broods affect some species eg Papilio bianor, maackii.
However there are areas in the tropical belt where the main factor is the rain & dsf is probably due to the decreased humidity.
This will affect the non-feeding pupal stage . Even if it rain the lower humidity is enough to trigger some changes in the pupa, a process not reversible by subsequent rain.
The susceptibity to change will varies from species to species. M. leda may need a small drop in humidity.
In Singapore a pupa in a rain-shelterd spot but exposed to the sun may soon experienced a severe drying effect. M. perseoides seem to have a dsf form in Singapore.
Singapore. http://1.bp.blogspot.com/-jx3Ps1jjyS..._adult_03Y.jpg https://media.mnn.com/assets/images/...utterfly_0.jpg
TL Seow : Cheers.
Last edited by Psyche; 23-Oct-2017 at 07:21 AM.
Reason: clarification