Much as I like Swords & Wizardry, it's distinctly lacking in malevolent frog-men carrying out the will of Tsathoggua. I now shall rectify this oversight.
Players in my Dwimmermount campaign should not, of course, interpret this post as indicative of anything they may or may not encounter in the bowels of that mystic mountain. Really.
Armor Class: 4 
Hit Dice: 2
Attacks: 2 claws (1d6), 1 bite (1d4) or 1 weapon (1d8)
Saving Throw: 16
Special: Breathe Water, Hop, Paralyzing Bite
Move: 9 (swim 12)
Challenge Level/XP: 4/120 XP
Ranine are degenerate, subterranean creatures who serve the foul frog-demon Tsathoggua. Like their master, the Ranine are of broadly batrachian appearance but possess small bat-like ears in addition to vicious fangs and, in many cases, small horns. They are drawn to underground locations suffused with Chaotic energies, so many also possess chaotic traits of both the major and minor varieties.
Ranine shy away from sunlight and suffer a -1 penalty to their attack rolls and saving throws when they operate aboveground. If given sufficient room in combat, these creatures can hop at enemies, which gives them a +1 bonus to attack and damage rolls. When fighting at close quarters, they try to bite opponents in order to inject them with a paralyzing poison. Failure to save against it results in paralysis for 3D6 turns. Ranine in groups larger than six typically include a leader, who can cast clerical spells as if it were a cleric of the same level as his hit dice.
Precisely how the Ranine reproduce is a mystery, as they appear to be completely asexual. Given that these beings prefer to take opponents prisoner rather than slay them outright, some sages have postulated that the Ranine somehow "convert" their prey into new frog-men to swell their ranks. If true, these creatures pose an even more terrible threat to civilization than is commonly supposed.