Sympetrum sanguineum Newman, 1833 (Odonata, Anisoptera) - only one species with dimorphic females or two sibling species with identical males?

In this paper it is described a new Sympetrum species - Sympetrum bigeminus sp. nov. from Romania. The male of this new species is similar almost to identity with Sympetrum sanguineum from which differs only in the more conspicuous lateral thoracic sutures. The females are different from Sympetrum sanguineum by the vulvar scale, which is prominent (well visible in lateral view), incurved, with a deep concavity, and shortly bilobed, thus showing morphological characters of a different and distinct species.