Come to think of it, anyone else find it lame that the 'loths all have modern animal features?

I think yugoloths looked exactly how they do now long before the mortal animals they superficially resemble, or any mortal life at all, existed. 'Loths have nothing to do with animals, so I don't like the idea of them reflecting contemporaneous animal life. Arcanoloths look like jackals because the meanings of jackals existed long before jackals did.

Then why do the Obyriths all reflect ancient animal life? I mean, I'm sure Obox-Ob adopted the rodent associations later, but refuse-feeding arthropods and worms date all the way back to the Cambrian explosion. Dagon also possesses features of many bygone-era animals-- namely cephalopods and early fish (yeah, cephalopods still exist to day, but they first sprang up IIRC in the Devonian or Carboniferous) He also possesses reptilian hands.

The Baernaloths are uber-ancient, hidden/reclusive evils-- the progenitor race to all fiends. They're not going to change for anybody. Besides that, representing an extinct animal = more alien, which for prettymuch every extant sentient race = automatically more frightening. Though come to think of it, why would they WANT to go to the trouble of taking a new form if they don't intend to ever be found by mortals?

Here's some yugoloth types that I would add:

Fornicoloth: Voluptuous beauties with divination-thwarting powers who polymorph into beautiful demons or devils in order to seduce generals and other leaders in the Blood-War and extract their secrets (before anyone groans at the name, it's not any worse than Canoloth *dog*, Skeleroth *need I even say?* Nycaloth *night*, Piscoloth *fish*, Echinoloth *starfish/sea urchin/sea biscuit*, Mezzoloth *middle/medium*, or Ultroloth...)

Kleptoloth: Worm-like low-end loths with tentacle-like whiskers. It is their duty to covertly collect overdue debts by secretly robbing the debtor at most inconvenient times. Being stretchy, rubbery worms, they can squeeze through the tiniest of spaces. They carry collected debts in their Stomachs of Holding.

Limoloth: Skeleroth-like loths whose aura deprives all mortal life within range of nutrients, causing starvation within minutes (and eventually death if said mortals cannot escape)

Those are the ones I can think of just immediately off my head. I'm sure I could eventually think of others. Looking at the list of Eugathodaemons and Cacodaemons on Theoi.com, the following themes are also fitting of yugoloths:

--amnesia
--helplessness
--Mockery/ridicule/blame (actually sounds fairly amusing and quite yugoloth-like. Imagine trying to defeat a tag-team of Tanar'ri while a Momoloth keeping a healthy distance from the battle ridicules your every move along with the style of your armor or robe. Then, he turns to the female thief and comments about the asymmetry of her breasts, and comments that the obscene size of the barbarian's axe indicates he is surely compensating for the miniscule size of his manhood.)
--silence/quiet/peace/loneliness (creature spreads the disease known as "Animus Blindness", identical to Life Blindness from the Book of Vile Darkness, except that it blinds the victim to anything possessing an animating spirit, which also includes undead, deathless, and sometimes even non-living constructs.)
--poverty

Most of the Yugoloths mentioned here along with the concepts apply to the Old Paradigm, though the Fornicoloths, Kleptoloths, and Momoloths are part of the New Paradigm.

EXTRA GOODIES

brief history of Taba: Taba, like most Yugoloth lords, is extremely old, and was originally part of the Old Paradigm. Back then, she was the thief of youth and health, inflicting lassitude, wasting, and premature age on her victims. With the Great Migration to Gehenna, she changed her portfolio to perfectionism and theft (Particularly Hellbreakers and Abyssbreakers)
Taba appears as a lovely, lithe humanoid thief with garnet-red pupils, small bat-like wings and a long spiny tail. The wings are too small for flying, but are just large enough to to slow and/or direct her fall. The wings are very flexible and can be draped over her shoulders to minimize space. Her spiny tail is prehensile and highly useful for grappling creatures or objects-- it is primarily used for the latter. Her skin has chameleon-like powers of camouflage and can exude a slimy mucus (as per the Grease spell) if she so wishes, used primarily for escape artist attempts. She possesses both a set of lungs and a set of gills.

Bubonix: Bubonix is the Yugoloth lord of misinformation, deceit, poison, ambition, and sabotage. Along with Syphilia (see Lady of Flattery below) and the Oinoloth, he makes up the triumvate of the three most powerful Yugoloth lords aside from the General of Gehenna himself. The festering sores on his body come in a myriad of colors, sizes, and appearances, and each kind oozes a different type of poison.

Cholerix: Cholerix is a minor Yugoloth Lord of mercenaries, greed, ruthlessness, massacres, raids, marauderers, collateral damage, and opportunism.
Bubonix's success so far is due largely to Cholerix's merciless treatment of the Gehreleths and other natives in kind.

The Oinoloth's portfolio is disease, pain, despair, and dogged adherence tradition.

NEEDED YUGOLOTH LORDS:
The following is a summary of Yugoloth lords needed in the setting:

--Lady of flattery, guile, and leaked military secrets
Yugoloth lord of Gehenna whose portfolio is the use of sex and flattery for infiltration and manipulation. In fact, she is one of the three most powerful of the yugoloth lords aside from the General of Gehenna-- of equal power to the Oinoloth and Bubonix, and her full portfolio also includes bribery and drug use. In her natural form, she is a voluptuous humanoid with spined, razor sharp wings, large breasts, and... .
...
Okay, there's no way of describing this in a detached scientific way without it being incredibly obscene. Essentially, she's a dick-girl. However, she can polymorph into other inviting forms *and genders* and can alter her external genitalia into whatever form she wishes.) As lame as the name sounds, I'm going with Syphilia unless anyone can come up with a better name (and I'm just now noticing the double-pun here, as ~philia is the Latin suffix for love). As the Lady of Bribes, she is dressed in luxurious clothing and much jewelry.

--Lord of Interrogation
A many-spined yugoloth lord of interrogation, torture, prolonguing of agony, and evil applications of healing and medicine. He lives on the Gray Waste. As expected, this Yugoloth lord not only possesses the Heal skill, but also many spell-like abilities for healing-- only used to prolong a victim's suffering.

--Lord of Disaster
Appearance not decided, but he exists on the Gray Waste. While Bubonix is the lord of man-made disasters, the Lord of Diaster is the lord of natural disasters-- disasters of the elements (fires, storms, floods, etc.), famine/starvation, as well as the helplessness and powerlessness that accompanies them.

Hermaphroditic is too vague (for instance, it could mean she has a separate set of both types, or that they're ambiguous)

Also, the reason I just went with "she's a dickgirl", is that if you actually look closely at most of the drawn dickgirl porn out there (if you must know, I only look for the lulz since dickgirl smut often has other hilarious weirdness going on in it), you'll note that (at least in most of the pics), the chicks don't actually have male genitalia or both male and female genitalia, but rather a set of highly modified female genitalia (I'm sure that unless you're either a chick or familiar with comparative anatomy or embryology that you have no idea what that means, but if you are familiar with any of the above, you probably have a pretty good idea what I'm getting at.)