Cleon
Legend
Although it is Medium, a monitor lizard is only 3 to 5 feet long, so I'd just use that and call it a day.
That's a bit tougher than I would like, I was thinking something halfway between a Monitor Lizard and a regular Lizard, e.g.:
Riding Lizard
Small Animal
Hit Dice: 1d8+1 (5 hp)
Initiative: +2
Speed: 30 ft. (6 squares)
Armor Class: 14 (+1 size, +2 Dex, +1 natural), touch 13, flat-footed 12
Base Attack/Grapple: +0/-12
Attack: Bite +3 melee (1d4)
Full Attack: Bite +3 melee (1d4)
Space/Reach: 5 ft./5 ft.
Special Attacks: —
Special Qualities: Low-light vision
Saves: Fort +3, Ref +4, Will +0
Abilities: Str 11, Dex 15, Con 13, Int 2, Wis 12, Cha 2
Skills: Listen +3, Spot +3
Feats: Run, Weapon Finesse (B)
Environment: Warm forests
Organization: Solitary or herd (2-20)
Challenge Rating: 1/4
Advancement: —
Level Adjustment: —
A lizard that looks like a yard-long iguana with unusually long legs and a shortened tail.
Riding lizards are a herbivorous reptiles of unusual intelligence and sociability that can be trained as mounts or beasts of burden. Their small size means they are mostly used by tiny humanoids, especially the Cayman lizardfolk.
A riding lizard is 2 to 3 feet long (excluding tail) and weighs about 40 pounds.