Try these (based only on the movie version):-
Species: Arachnid
Type Mass Strength Dexterity Endurance
Eater 500 kg 4d6 3d6 4d6
Weapons: Mandibles (Teeth) +2
Armour: 3
Species: Winged Arachnid
Type Mass Strength Dexterity Endurance
Hunter 200 kg 3d6 4d6 3d6
Weapons: Mandibles (Teeth) +1
Armour: 2
Note: This species can fly, and it exhibits the behaviour of an aerial Hunter when stalking its prey. It prefers to bear its victims away to a high location, to feed upon its meals at leisure.
Species: Brain Bug
Type Mass Strength Dexterity Endurance
Eater 5000 kg 2d6 1d6 2d6
Weapons: Special
Armour: 0
Note: Incapable of movement under own steam. Has to be borne by a carpet of smaller (1kg) servitor drone bugs.
Note: Telepathic, Psionic Strength 12, Telepathy (constant low level Telempathic communication with all arachnids within Planetary range, costs 0 Psionic Strength). Does not know Shield or Assault psionic powers, though can use the Probe telepathic power.
Special Weapon: Brain Consumption: The Brain Bug uses a long, articulated spike like a large ovipositor. Thrusting this into the head of its victim, killing the victim instantly, the brain bug sucks out the victim's brain matter.
The brain bug acquires the victim's thoughts and memories - over the six hours required to digest the human brain matter, the bug can roll its own Intelligence and / or Education, and use up to 1d6 of the victim's skills including Tactics skill, if any.
Alternatively, the brain bug can use the consumed brain matter to restore any Psionic Strength points it may have spent.
Species: Tanker
Type Mass Strength Dexterity Endurance
Eater 20000 kg 10d6 3d6 10d6
Weapons: Plasma +3
Armour: 5
Special Weapon: Plasma The Tanker shoots a spray of burning, toxic, acidic plasma from its front mandibles, extending outwards in a cone roughly twenty metres by ten. All caught in the srea of effect are affected. If the plasma hits organic matter, it does 2d6 damage per combat round to the target. Full body armour alone protects agains the plasma, but the plasma dissolves all armour but ship's hull plating at a rate of 1d6 points per combat round.