Rare biological phenomenon spotted in dragonflies

A male Scarlet Skimmer.

A male Scarlet Skimmer.  

When Renjith R.V and Vivek Chandran spotted a peculiar dragonfly, the Scarlet Skimmer (Crocothemis servilia) , in the Puzhakkal area of the Kole wetlands in Thrissur last year, little did they know that they were documenting a very rare biological phenomenon.

Even though the dragonfly was perched in the deep marsh, Mr. Renjith managed to take a photograph of it. They were puzzled by its appearance as male dragonflies typically have a prominent blood-red colouration in almost all the body parts, including the head, thorax, abdomen and legs, and the female is pale yellow in colour with a dark brown thorax and legs.

But the one they spotted on July 14 as part of the Kole Odonata Survey 2019, conducted by the Society for Odonate Studies and Kole Birders in association with Kerala Agricultural University and the Kerala Forest and Wildlife Department, was “part red and part yellow”.

Later, while compiling data, they were thrilled to find that they had recorded ‘gynandromorphism’ — a very rare biological phenomenon. Their finding has been published in the latest issue of the Journal of Threatened Taxa under the title ‘A Record of gynandromorphism in the Libellulid Dragon fly Crocothemis Servilia from India’.

Genetic aberration

Gynandromorphs are chimeric individuals having both male and female tissues and it is viewed by the scientific community as a genetic aberration. Even though common in some arthropod taxa such as Crustacea and Arachnida, the paper says it is very rare in odonates and only 30 individuals from seven families have been reported with the condition worldwide.

The spotted individual showed bilateral gynandromorphism of only the thorax, half of which showed blood red colouration as in males and the other half pale yellow characteristic of females. The base of the wing of the red half was marked with rich amber, in contrast with the other wing base which was paler. The head, legs and abdomen showed typical female morphology.

It had mixtures of male and female external characters ranging from almost entirely female to about equally divided. They were symmetrical in development with normally dimorphic structures mostly having characters intermediate between the typical male and female conditions.

Further research has to be undertaken to investigate the influence of environmental factors on this phenomenon, says Renjith, a school teacher in Palakkad and Vivek, a Ph.D. scholar in dragonflies.

The Society for Odonate Studies has been conducting surveys at Kole wetlands since 2018 and 37 species of dragonflies and damselflies have been reported from the wetlands so far.

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