The species traditionally placed in Pseudostigmatidae are all Neotropical. Two range as far as northeastern Mexico: Mecistogaster ornata occurs in Tamaulipas and Pseudostigma aberrans in both Tamaulipas and Nuevo Leon. In 2006, molecular phylogenetic analysis confirmed that the African damselfly Coryphagrion grandis, previously often classified within Megapodagrionidae or in a monotypic family Coryphagrionidae, belonged within family Pseudostigmatidae, close to genus Mecistogaster, as was proposed already ten years before. This finding suggests that the family dates back to before the breakup of the supercontinent Gondwana.

Adults of the family are exceptionally large for damselflies, with wingspans as high as 190 mm reported for Megaloprepus and body length up to 130 mm for Pseudostigma aberrans. The pterostigma - a thickened, pigmented cell found on the leading edge of the wing in other odonates - is either missing or else modified into a pseudostigma of several cells. In some species the pseudostigma is a large colored spot covering most of the tip of the wing.

Mecistogaster is a genus of large Neotropical damselflies in the family Pseudostigmatidae. It contains 11 species.

Mecistogaster ornata (Rambur, 1842) ranges in Middle America from Mexico, Guatemala to Panama, and South America. It is a very large damselfly, with body length 86-87 mm. Adults fly in understory of rainforest where they apparently glean spiders and wrapped spider-preys from webs. Larvae, described by Ramirez, breed in water-filled holes of trees. Hedstrom and Sahlen found this species was missing entirely from non-seasonal, tropical wet lowland forest and non-seasonal, tropical moist forest at mid elevation in Costa Rica, while it was active year round in seasonal, tropical dry lowland forest and tropical semi-dry forest, as well as in seasonal, tropical moist evergreen forest and tropical montane moist forest, both at mid-elevation. 

Male identification: 
    - Abdomen length 82 mm.
    - Large with elongate abdomen. 
    - Thorax dark with yellow stripes. 
    - Wing tips yellow on upperside, becoming dark on underside with age. 

Female identification: 
    - Similar to male. 
    - Abdomen length 77 mm, hindwing length 54 mm.

The species is native to Argentina; Brazil; Colombia; Costa Rica; Ecuador; French Guiana; Mexico; Panama; Peru; Suriname; Trinidad and Tobago; Venezuela, Bolivarian Republic of. This species is known from over 50 locations (many being within protected areas) but there is no data available on population sizes.  The species is accessed by IUCN Red List as Least Concern.

Accepted subspecies include:
     - Mecistogaster ornata acutipennis  (Selys, 1886) 
     - Mecistogaster ornata ornata  (Rambur, 1842)