Hi, uh, here's my attempt at the encyclopedia texts! I did my best to describe the aliens' improvements without knowing the concrete details.
FLOATER CONSUL (ol' green cape)
Live: These abominable beings constitute the elite of the Floater social heirarchy. While the exact nature of the Consuls' authority is unknown, sightings indicate that they direct the hideous human experiments aboard Floater ships and lord over the abductees. In combat, Consuls have the devil's speed and a frightening constitution above that of their lesser brethren.
Dead:
Cross-sectional analysis with common Floaters reveal that Consuls deviate little from their minions in phsiology, aside from cursory mechanical improvements to the life support and levitation systems, likely token symbols of their status. It can be assumed that the Consuls' extraordinary lethality is simply trained, an occurrence so rare in the alien military as to seem perversely admirable.
SECTOID ORION (plural: Orions) (elite sectoid)
live: A mysterious Sectoid subspecies, distinguished from their common brethren by skin color. Though physically meager, the Orions possess superior brains which manifest in the forms of supernormal cognitive and psionic ability.
dead: On closer inspection, this subspecies appears to have been cross-bred with another race entirely, inheriting a highly cultivated psionic strength and unusual tissue pigmentation. While organ and bone structures are largely unchanged, Orion brain tissue is far denser than that of a common Sectoid. Any further genetic deviations are unknown, as are the origins of the anomalous genes.
SHOCK MUTON (black muton)
Live: Whereas common Mutons move very deliberately, displaying a slow and impervious sense of power, these Shock Troops move as if there were sulpheric acid coursing through their hearts. The jump pack bestows great mobility, allowing them to plough through obstacles even more frighteningly than a common muton.
Dead: The Shock Muton's biology is identical to that of a common Muton; its one catch is a surgically implanted hormone controller, no bigger than a child's fist. This small metal box can trigger the production of a norepinephrine-like hormone in such exorbitant quantities as to drive an average human insane. The jump pack appears to have been crudely wired direct to the nervous system.
MUTON WARLORD: (red muton)
Live: Marked by regal red catsuits, these despotic overlords rule the Mutons in battle. Each the equivalent of ten Genghis Khans, they rampage mercilessly wherever they are set loose. Though physically dominant, they are clearly too savage to provide any sort of complex leadership; thus, it may be assumed that directions come mainly from a higher power, and that Warlords are, in a sense, lords in name only.
Dead: Autopsy of the Warlord reveals a terrifying network of invasive implants and drug-enhanced musculature; this is, quite literally, a Muton on steroids. The cranial cavity and vital organs are shielded by thin, flexible alloy plates which have been fused to the bone structure. A hormone controller is installed beneath the ribs, capable of flooding the specimen's body with an agonizing fury. The most striking feature, however, is a cranial "skull cap," resting just below the alloy plating. This curious brain shield seems to have the property of deflecting all psychic attacks upon the Warlord's mind, without disrupting commands from its masters. The exact mechanics of this operate far above our current understanding of psionics.
CHRYSSALID GERMINATOR (pink chryssalid)
Live: Like the common Chryssalid, the Germinator is able to inject its victims with unborn offspring. This subspecies, however, ejects its young from the mouth in an acidic discharge. The projectile spawn is concealed in a jagged shell which penetrates the victim's body on contact, breaking the skin and then inseminating the host with a burning acid payload.
Dead: The eggs in this Chryssalid subspecies are kept in a repulsive hive of gelatinous sacs, each throbbing with acidic ichor. A long "fallopian tube" connects the egg sacs to the throat, effectively allowing the Germinator to discharge its spawn at a distance with a voluntary muscle contraction.
SNAKEMAN GLYCON (dark snakeman; other optional names: Krait, Gorgon)
Live: This frightening Snakeman variant is capable of unnerving speed. The Glycon exhibits an unsophisticated aggression beyond that of common Snakemen, although it appears to be no more or less intelligent. Furthermore, the darker skin pigmentation implies an even more extreme heat tolerance.
Dead: Inspection of this variant specimen reveals a snake-like tail much more powerful and capable of quick acceleration than that of its common brethren. Curiously, this immense muscle occupies so much of the Glycon's body that it contains no eggs, and appears to be incapable of reproduction altogether. We may extrapolate that this specimen was engineered exclusively for combat, and is incapable of social or sexual interaction. Samples of the darkened tissue confirm that this specimen boasts a heat resistance beyond that of any humanoid organism we have yet encountered.