Monday, February 28, 2011

37. Ceriagrion olivaceum olivaceum (Laidlaw, 1914)

Number: 37
Family: Coenagrionidae
Genus: Ceriagrion
Species: Ceriagrion olivaceum olivaceum
Common name(s): Rusty Marsh Dart
Habitat: Small ponds (uplands & lowlands)
Province(s) sighted: Nam Nao National Park (Petchabun); Phu Khieo Wildlife Sanctuary (Chaiyaphum); River Chi and Nam Phong NP (Khon Kaen); Khao Soi Dao NP (Chantaburi).  Sightings (by me): Uncommon
In flight (that I have seen): November-February

I saw a female of this species about two years ago in Khon Kaen, but I never seen one since. When I visited Khao Soi Dao National Park last December, however, I saw several! Near the entrance there was a small pond that had a number of species. Just away from the water's edge in the grasses, I saw a Ceriagrion species and soon realised that it was Ceriagrion olivaceum. A new species for me! There were a number of females, but I only saw one male. Since then, I have spotted males at a small number of other places, though I am yet to spot another female.

The male
Both sexes are very similar, but the male has a little more yellow/brown colouration to the abdomen. That said, I have now seen many specimens and the colours seem to vary slightly, especially on the abdomen.

This male from Phu Khieo WS, has a reddish upper abdomen and is almost white on the underside.

Another from Nam Nao NP, with a more uniform brownish abdomen.

The female
The female is paler in colour but both sexes have a distinct 'olive' coloured thorax, which I presume gives it its name.

Here is the first female I saw at Khao Soi Dao NP.

It seems to be more common than I first thought and that it may easily be overlooked. It is quite difficult to spot and tends to hide away in the long grasses.

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