Wraith Spider, Large (CR 3)

Large Undead
Alignment: Always chaotic evil
Initiative: +2 (Dex); Senses: tremorsense, darkvision 60 ft., Listen +6, and Spot +5

AC: 13 (-1 size, +2 Dex, +2 natural), touch 11, flat-footed 11
Hit Dice: 4d12+3 (29 hp)
Fort +1, Ref +3, Will +4
Speed: 30 ft., climb 20 ft.
Space: 10 ft./5 ft.
Base Attack +2; Grapple +1
Attack: Bite +4 melee
Full Attack: Bite +4 melee
Damage: Bite 1d8+4 plus 2d4 Strength
Special Attacks/Actions: Strength damage
Abilities: Str 17, Dex 15, Con -, Int 2, Wis 10, Cha 1
Special Qualities: undead traits
Feats: Alertness; Toughness
Skills: Listen +6 and Spot +5
Advancement: 5-9 HD (Large)
Climate/Terrain: Any underground
Organization: Solitary
Treasure: None

Source: City of the Spider Queen

Wraith spiders are undead creatures formed from the chitinous husks of monstrous spiders but animated by evil spirits from the realm of Kiaransalee.

A wraith spider appears much like it did in life, except that its eight eyes are hollow sockets through which the empty interior of its shell is dimly visible. A shadowy aura surrounds the creature, congealing to pure blackness around its fangs.