Based on what I read of this scenario, here is what I was able to come up with for a playable race. Perhaps a fallen comrade is replaced with a ghibrani who wishes to follow along and learn what they can, eventually leaving Elytrio.
GHIBRANI RACIAL TRAITS
Ability Adjustments: See Subspecies.
Hit Points: 4
Size and Type: Ghibranis are Medium monstrous humanoids with the ghibrani subtype.
Desert Stride: Ghibrani can move through nonmagical difficult terrain in deserts, hills, and mountains at their normal speed.
Reciprocal: Ghibranis receive a +2 racial bonus to Diplomacy checks.
Subspecies: Ghibrani belong to one of two subspecies: Husk or Membrane. All ghibrani start with -2 Intelligence, +2 Charisma at character creation. Ghibrani Husks receive a +4 racial bonus to saving throws against radiation effects. Ghibrani Membranes gain an extraordinary flight speed of 30 feet with average maneuverability. Additionally, Ghibrani Husk are hardy and resilient (+2 Constitution), while Ghibrani Membranes are lithe and more graceful (+2 Dexterity).
Low-Light Vision: Ghibranis can see in dim light as if it were normal light. For more details, see page 264 of the core rulebook.