This Cordulid I photographed near the start of the Maromba trail (near Hotel Simon) in Itatiaia. It belongs in the genus Neocordulia (Garrison, Von ellenrieder and Louton).

She looks more or less similar to the female Neocordulia in this link:
http://www.macromia.com/Downloads/Trip_Report0311.pdf
But.... I haven't been able to find any other Neocordulia pictures yet.

03/02/2008
The Neocordulia taxa that might be possible here, are:
N. androgynis
N. carlochagasi
N. mambucabensis
N. matutuensis
N. setifera
N. volxemi
This is based on the range given on Dennis Paulson's website.

13/3/2008
literature examined in Naturalis.

First some abstracts from the descriptions in:
M.L. May, 1992. A review of the genus Neocordulia, with a description of Mesocordulia subgen. nov. and of Neocordulia griphus spec. nov. from Central America, and a note on Lauromacromia (Odonata: corduliidae). Folia Entomologica Mexicana 82: 17-67.

Androgynis
Androgynis has yellow costa and pterostigmata yellowish-brown, grey-brown body with black dorsolateral spots and lateral and middorsal streaks on most segments, segments 7-9 moderately widened an dnot depressed dorsoventrally, face mostly clear yellowish-tan, pterothorax with metallic areas brilliant grass green. femora light brown, sometimes darker distally, tibiae pale on extensor surface, variable dark stripes laterally and apically, with black setae; tarsi dark.

Carlochagasi (female unknown)
face mostly ochraceous with no metallic blue, Pterothorax with metallic green areas brilliant green. legs ochraceous except apical 1/3 of femora and femorotibial joints nearly black. Costa light brown. Segments 7-9 strongly widened.

Setifera
face mostly yellow-brown, nearly concolorouson vertex with no metallic blue. Pterothorax with metallic areas rather bright green, without blue overtones. Femora brown in basal 2/3 to 3/4, abruptly changing to black distally, tibiae an tarsi black. Wing veins, influcing costa and pterostigmata black or very dark brown. abdomen black or dark reddish brown dorsally and dorsolaterally. Segments of 7-9 in female hardly widened, not depressed.

Volxemi
face yellowish to orange-brown. Pterothorax with metallic areas bright green. Femora mostly orange-brown, shading to dark brown at apexes, tibiae and tarsi dark brown.

Matutuensis (Machado, 2005, taken from that article)
labium, labrum yellowish, remaining parts of olive brown. Pterothorax brown, covered with yellowish pilosity with bright metallic green areas.... Femura brownish with the distal third or fourth black. Tibiae black except fro the keels that are yellow. Tarsi black. pterostigma dark brown.

Mambucabensis (Costa and Santos, 2000, taken from that article)
Face yellowish brown.... Pterothorax reddish broen with large areas of metallic green and covered with numerous yellowish setae. Coxae, trochanter, proximal ends of femur and tibiae light brown, distal ends of femur and tarsi black. All tibiae keeled along its entire length. Wing venation black, pterostigma light brown, small
Segments 1-10 yellowish red dorsally. Thge female is closest to N. setifera but differs from it by characeteristics cited i the key.
Costa and Santos (2005) contains a key to the subgenus Neocordulia.

All in all I come to the conclusion that it must be a female Neocordulia setifera or Neocordulia mambucabensis.
Following the key in Costa and Santos, I come to the same conclusion:
1 costa dark.... (not pale)
3 cerci black... (hot yellow)
4 a Total length: 56-57 mm; metafemur 14 mm; pterostigma dark-brown; metafemur with spines along anterolateral angle large and close-set, those in distal 1/3 longer than half the distance between adjacent spines; abdomen length 42 mm......setifera
4 b Total length 45 mm; metafemur 12 mm; pterostigma yellow; metafemur with spines along anterolateral angle smaller and more widely spaced; abdomen length 32 mm.
[copied from Costa and Santos: Neocordulia mambucabensis spec. nov., a new dragonfly from rio de janeiro, Brazil (anisoptera: corduliidae). Odonatologica 29(3): 247-253.

Although I cannot recall the measurements (larger in my memory), I tend to opt for Neocordulia mambucabensis on the basis of pterostigma colour, leg colouring (brown tibiae, not black). The abdomen colouring confuses me, as it seems too dark for the descibed colour of N. mambucabensis and too light for the described colour of N. setifera.
.... although most of those are not in the Key, but they are in the descriptions...
spines on metafemur - have to work on that one....