Photographed at Lagoa Cigana. Tim Manolis identified this damsel as Helveciagrion spec, probably H. simulacrum or H. obsoletum. Unfortunately it seems the quality of my photos isn't good enough to make a definite identification, based on the appendages.

13/3/2008
Today I checked the original descriptions of both species in the Annals of the Carnegie Museum, Volume 6 (1909) on pages 173 and 176. The names were then Acanthagrion chirihuanum and Skiallagma simulacrum. Machado introduced the genus Helveciagrion in 1980 in an article in Lundiana, which I cannot check here at the museum. Recently Helveciagrion chirihuanum turned out to be a synonym for Leptagrion obsoletum (Selys 1876). So now the name for this species is Helveciagrion obsoletum.

So now I am comparing Helveciagrion obsoletum (chirihuanum) with Helveciagrion simulacrum.
From both descriptions it seems that the species are fairly similar. The individual on these photos seems more similar to Helveciagrion simulacrum.
- prothorax seems to have a little bit of black, which should be present in simulacrum and not in obsoletum.
- pterothorax has a black line along the humeral suture, which should be present in simulacrum and not in obsoletum. Obsoletum only has a black mark on the upper end of the humeral suture.
- S2-3 however seems closer to Obsoletum, which has a 'short isolated transverse band on the dorsum of 2 at two-thirds length and the hindmost sixth of 3' black. Simulacrum has a 'rounded spot on the posterior half of 2 connected with the hind end of the segment and in some with the anterior margin by a mid-dorsal black line, and the hindmost fourth of 3' black.
- S10 seems all-black, seeming to fit neither of the two. Obsoletum has S8-10 blue. Simulacrum has S8-9 and the sides of 10 blue....

So.... I still don't know....
Next time I want to check the original description of 'Leptagrion obsoletum' and the description of Helveciagrion vulcanoae (which is not available in Naturalis).

Helveciagrion is now considered a junior synonym of Telebasis (Garrison 2009)