The Elysian Desert is a swamp-like region that exists three miles to the west of the Omaticaya territory. The name was given as a joke to early RDA explorers for it's toxic fumes and highly volatile chemicals that were found in the swamp. The Na'vi do not venture anywhere near the region as they percieved it to be an unholy ground where exists all nightmares and demons. It is believed the swamp came about as a direct result of floodings from the nearby mountains. As rivers and streams could not form, the water became trapped within the rich ground that was deeply seeded by large trees and stubborn vegitation that refused to die.
The known flora within the Elysian Desert are quite common and could easily be found anywhere else on Pandora. With the few exceptions. Certain willow trees have mutated to thrive on the chemically toxic waters, using it to produce highly hallucinogenic properities that are stored in the glowing tendrils of the tree. Other flora such as webbed vines and thick bushes exist here simply to supplement on the toxic waters for their own personal and still unresearched use. By all means, no flora let alone fauna could rightfully exist within this lethal swamp.
Prior to the search party led by Jia Hawthorne into the swamp, early RDA explorers could only hover by Samson vehicles to research on the region. Knowing that settling in and talking a simple walk into the swamp was certainly a dangerous task. As resources were severely limited during the early phase of colonization, the explorers only mapped and catalogue what they could. No known fauna was spotted during a brief time there. When the search party was tasked into going in this region, they were not prepared to encounter creatures that did not resemble anything close to what was catalogued elsewhere on Pandora.
The nicroarachnia is a newly discovered species named by Dr. Simon Jei-Suun, a xenobiologist stationed at Hell's Gate. These creatures resemble somewhat to spiders commonly found on Earth yet the difference between the two are radical. Due to the harsh environment of the swamp, the creature is believed to evolve in the toxic swamp of the Elysian Desert, developing scales to withstand the acidic waters. A gas-sac like organ beneath the body allows for a sharpened needle-like weapon to be fired out from the sac and directly into flesh. Once the needle made contact with the flesh, a poison of unknown chemicals react with blood, causing a violent reaction before exploding. The damage as a result can be lethal if hit at critical parts of a body.