There are three Ischnura species on Cuba: Ischnura capreolus, Ischnura hastata and Ischnura ramburii.
Ischnura ramburii resembles Ischnura capreolus but the difference is in the last two segments of the abdomen.
Ischnura ramburii has segment 8 completely blue while Ischnura capreolus has segment 9 (the last segment) completely blue.
The other Ischnura sp. occurring on Cuba, Ischnura hastata, looks totally different and does not have a blue segment at the end of the abdomen.
Rambur's Forktail is one of a number of damselflies that have two forms of female, one colored like the males and one colored differently.
One theory is that the females that are colored like males may be relieved of the constant pressure by males to mate.
Females may gain nothing by numerous additional matings after their first mating, and such matings can interfere with their feeding and predator avoidance.

Playa Larga area, Cuba, 12 January 2016