Kerala gets a new dragonfly added to its insect fauna

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The south Indian state of Kerala has got a new entrant to its list of insects recently when a group of researchers have found Microgomphus souteri Fraser, a dragonfly which was not spotted from the state in the past. The fly adds to the 138 member strong Odonata fauna of Kerala.

The new fly adds to the 138 member strong Odonata fauna of Kerala. The insect was spotted from Vlayamchal in the Aaralam Wildlife Sanctuary in Kannur district which is located in the slopes of the Brahmagiri ranges in northern Western Ghats.

The fly which belongs to the Microgomphus genus actually comes under Gomphidae family of dragonflies which are also known as Club-tails for the bulbous last segment of their abdomain. The Microgomphus members of Gomphidae are the smallest in the family with a unique appearance of black and greenish yellow colours.

Microgomphus souteri 
found in Aaralam Wild Life Sanctuary in Kerala
(Photo courtesy Dr.  Mohammed Jafer Palot )

According to researchers, the discoidal cell on the fore wing and hind wing of these flies differ in their shape. Moreover, the fore wing is shorter than the hind wing. The absence of an incomplete basal antenodal nervure and inner branches of superior anal appendages makes them distinct. Slightly notched inferior appendages and the presence of more than two transverse nervures between the sectors of the arc, also helps identifying the genus Microgomphus.

Among other members of the genus Microgomphus, M. souteri  differs with Antehumeral stripes on its thorax which are not confluent with mesothoracic collar. Apart from other features, the two large triangular greenish spots on the black labrum also helps distinguishing them. The 4^th and 5^th abdominal segments of this fly don’t have the mid dorsal oval yellow spots while the 8^th and 10^th segments have no yellow markings.

However, it is also reported that the specimen collected from Aaralam Wildlife Sanctury showed minor variations from the specimen in the earlier record.

Distribution of Microgomphus souteri

Usually found in the humid parts of the Western Ghats and North East India from heights of 609.5 MSL and above, other members of this genus are reported from South Asian countries like Myanmar, Malaysia, Sumatra, Singapore, Sri Lanka, Cambodia, Laos, Vietnam, Borneo and Africa.

Though usually arboreal, the males of the species are found resting on rocks in the streams or vegetation on the banks of their parent rivers. India has four members of the species M. chelifer, M. torquatus (Selys, 1854) and M. verticalis (Selys, 1873), apart from M. souteri.

The  present study is the second recorded spotting of the species from India, the first being from Sampaje in Coorg district of the adjacent state of Karnataka some 88 years back.