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Friday, June 29

Kerala gets a new dragonfly added to its insect fauna

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, odonates in Aaralam Wilde life sanctuary, insects of Kerala
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 4th and 5th abdominal segments of this fly don’t have the mid dorsal oval yellow spots while the 8th and 10th 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.

Friday, June 8

Spider Diversity in India

Believe it or not, these eight legged creatures comprise the largest order of animals in the animal kingdom. As with other micro fauna, the Indian subcontinent is rich with spider diversity too. According to an updated check list in 2012 India has1685 spider species from 438 genera and 60 families . Among this, 91 species are Mygalomorphs or spiders with their fangs pointed down without crossing each other, as in other group of spiders.  The remaining 1595species belong to Araneomorphs, or spiders with fangs which are opposite in direction, crossing over to each other.

According to research reports, out of the total spider species found in India, 70 are exclusively from Karakorum area, or in other words, endemic to Karakorum area.

Critically Endangered Spiders of India
According to International Union for Conservation of Nature (IUCN) the international agency which monitors the conservation status of organisms,If the population decline is severe among a species which wipes away almost 90 percent of the population in a decade, that species can be considered as critically endangered.

 IUCN also suggest that if the extent of occurrence of the organism shrinks to 100 km2 area, or to a single location, it can be listed as critically endangered, indicating that it is closer to a possible extinction or a state where it no more exist in the face of the mother earth. If only less than 250 mature members of the species are known to exist, it also indicate that a species is critically endangered.

The Rameswaram Ornamental Spider (Poecilotheria hanumavilasumica)
Also known as the Rameswaram Parachute Spider, this beautiful organism is facing the risk of a possible extinction from the face of earth. This special spider has been so far found only from India, with the last record being from 2004.

The Rameswaram Ornamental Spider, Poecilotheria hanumavilasumica, Rameswaram Parachute Spider
The Rameswaram Ornamental Spider
These spiders are found to be semi-social which makes them live some time in groups or alone. These shy creatures tend to live in hiding and are found along the coastal savannah, tropical lowland rain forests and montane forests. They have been reported from altitudes up to 2000 m above mean sea level.
These spiders are dangerous with their ability to deliver quick poisonous bites. But their bits are not fatal in nature. However, they are finding their population falling down with their typical habitats being altered and degraded due to human intervention.

Present conservation status
According to IUCN, Rameswaram Parachute Spiders are restricted to a Rameswaram Island and the associated mainland close to the island, limiting its presence to a 100 km² area. However, based on the reports of occurrence, the actual area of occurrence of these rare species of spiders can be less than 6 km² area. IUCN documents claim that they are found on tamarind, casuarina and mixed dry deciduous tree and palm plantations here.
 Apart from the island, the species has been recorded from less than 15 severely fragmented locations also.
The alteration of habitat is the major threat to these spiders as their distribution is restricted. For instance, when the tamarind plantation sprawling to 5 hectares were recently grazed down by government authorities to build up government quarters, it killed all the 70 individuals found in the plantation. The flood o tourists and the associated construction activities are again sweeping away the remaining population of this rare spider.
Due to the loss of natural vegetation, continuing decline in area and absence of enough mature individuals may soon make this rare creature to vanish from the face of earth. Unfortunately, the legal machinery in India is yet o make any move to save this spider.

 The Gooty Tarantula (Poecilotheria metallica)
Also known as Peacock Parachute Spider, this magnificent creature is also facing risk of extinction in Indian subcontinent to which it is endemic. With a visually appealing steel blue color and patches of intense orange-yellow, black and white, it is also a victim of international pet trading rackets which smuggle them beyond borders to sell.
 The Gooty Tarantula, Poecilotheria metallica, Peacock Parachute Spider
Reported from Gooty (Ooty/Udagamandalam) and from forests between Nandyal and Giddalur in the state of Andhra Pradesh in South India, it is also believed to have an area of occurrence of less than 100 km².
While habitat loss and degradation are the major threats to this spider which is known to live in deciduous forests, international pet trade rackets are the second major threat to these small beautiful creatures. IUCN has issued a warning that at the present rate, the species may disappear from earth in the near future.