Within the realms of Tredecimos which contain at least one moon in relative cosmic proximity to life - namely Abaris, Arboria, Ventif, Trivalis, Petrifos, and Penumbris - there are humans and metahumans who become afflicted with one of the many variations of the curse of Bestiathropy, often referred to as Werebeasts. This curse is tied to the lunar cycle, causing the host to painfully transform into a large, semi-anthropomorphic animal form. The curse is spread intravenously when one of these Werebeasts bites another human or metahuman as-of-yet unafflicted with the curse.
Worth noting is that while Lumenis and Petrifos do have moons nearby, Lumenis is a realm of inherent Law and Good, devoid of the chaotic tendencies that come with the curse, or the inherent malevolence that it is often at the very least associated with; and Petrifos is a realm of stone, and werebeasts of that realm are often of a gem-skinned variety with rock hard teeth.
There are currently 20 known subsects of the Bestiathropy curse, and thus 20 different types of werebeast. Each branch of Bestiathropy is tied to a specific phase of the lunar cycle; with two to each crescent and gibbous phase, and a third to every other phase. Important to note is that certain realms which have a nearby moon, have their cosmic makeup in such a fashion as to only allow some phases of the lunar cycle. This, of course, would mean these realms are greatly limited in which werebeasts noticeably reside there. Studies have shown that it is incredibly rare for one to contract more than one type of Bestiathropy, however there have been reports of the occasional hybrid Bestiathrope; and even Werepyres (vampire- werebeast hybrids) have often been spoken of.
Below are detailed the physicalities, lunar relations, and behaviors of the Bufalusthrope, Bufothrope, Caprathrope, Castorthrope, Catusthrope, Coluberthrope, Dracothrope, Equusthrope, Falcothrope, Lepusthrope, Lycanthrope, Musthrope, Pardusthrope, Porcusthrope, Squalusthrope, Testudothrope, Tigristhrope, Trygonthrope, Ursathrope, and Vulpathrope.
The Bufalusthrope, better known as the Werebuffalo, is a Bestiathrope which presents as a large, shaggy haired, anthropomorphic buffalo in grey, brown or black coloration. Werebuffalos transform by the turning of the 3rd quarter moon.
Bufothropes, better known as Weretoads, present as anthropomorphic toads, twice in size than even most Toadish Amphibor. They are generally green, grey, or blue in coloration, and transform by the turning of the waning gibbous moon.
Caprathropes, better known as Weregoats, present as large, anthropomorphic goats in grey, white, brown, or black coloration. They transform by the turning of the full moon.
Castorthropes, more commonly known as Werebeavers, transform by the turning of the waxing gibbous moon into very large, muscular, anthropomorphic beavers, generally brown or black in coloration.
The Catusthrope, better known as the Weregorilla, transforms into a gorilla which is bigger than most normal gorillas; generally grey, silver, black, or brown in coloration, by the turning of the 1st quarter moon.
Coluberthropes, better known as Wereserpents, transform by the turning of the waxing crescent moon into large serpentine creatures. This particular branch is often looked upon with mockery, as it is generally considered off putting at the very least to see a snake the size of a boa constrictor with arms and legs. Wereserpents generally appear in black, green, or white coloration.
Dracothropes, better known as Weredragons, are afflicted with a strain of Bestiathropy which transforms them into anthropomorphic Dragons by the turning of the new moon. The particular coloration of the Draconic form derives from that of the one who bit them.
Equusthropes, better known as Werehorses, are bestiathropes which transform by the turning of the waning crescent moon into anthropomorphic horses. Werehorses often appear black, grey, white, or brown in coloration.
The Falcothrope, better known as the Werefalcon, transforms by the turning of the 3rd quarter moon into an anthropomorphic falcon creature. They are generally grey, black, or blue in coloration.
Lepusthropes, better known as Wererabbits, are Bestiathropes which transform by the turning of the waning gibbous moon into large, anthropomorphic rabbit creatures. They are generally grey, white, brown, or black in coloration; and relatively more docile than most other werebeasts.
Lycanthropes, better known as Werewolves, are generally the first thing that comes to mind when one speaks of werebeasts in general. By the turning of the full moon, a large, shaggy-furred, anthropomorphic wolf form is assumed. Lycanthropes are generally brown, grey, white, rusty red, or black in coloration.
Musthropes are better known as Wererats. Those afflicted with Musthropy transform by the turning of the waxing gibbous moon; into large, anthropomorphic rat creatures. They are usually red, white, black, or brown in coloration, though some are hairless.
The Pardusthrope, better known as the Werepanther, transforms by the turning of the 1st quarter moon; into a large, sleek, anthropomorphic panther creature. Werepanthers are generally black, dark blue, or dark brown in coloration.
Porcusthropes, better known as Werehogs, transforms into its anthropomorphic hog creature form by the turning of the waxing crescent moon. They are generally black, pink, or brown in coloration.
Squalusthropes are also called Weresharks. Despite being an inherently aquatic, fish based branch of the Bestiathropy curse, the anthropomorphic form of the Wereshark is able to breathe on land; making it more amphibious in nature than most would expect. The transformation into the Shark form is tied to the turning of the new moon; and they are often blue, grey, or white in coloration.
Testudothropes, also known as Weretortoises, are Bestiathropes which transform by the turning of the waning crescent moon; into their large, anthropomorphic tortoise form, complete with a large shell which they can recede into if needed. Weretortoises are calmer and less prone to violence than most Werebeasts; and are often blue, green, grey or black in coloration.
The Tigristhrope is also known as the Weretiger, and transforms into their anthropomorphic tiger form by the turning of the 3rd quarter moon. They are usually orange, white, or grey in coloration, with black stripes.
Trygonthropes, also known as Wererays, transform into a large, anthropomorphic stingray form by the turning of the full moon. Much like the Wereshark, these forms have arms and legs despite being fish based; and can breathe on land as well as water. They generally appear blue, black, or grey in coloration, with a peach or white belly.
Ursathropes, also known as Werebears, are those who transform by the turning of the 1st quarter moon, into large, anthropomorphic bear creatures. Werebears are usually grey, brown, black or white in coloration.
Vulpathropes, better known as Werefoxes, are Werebeasts which transform by the turning of the new moon into large, anthropomorphic fox creatures. They can be more playful rather than aggressive in comparison to most other Werebeasts; and are usually red, grey, black, or brass in coloration.

YOU ARE READING
Tredecimosian Beastiary
FantasyA growing collection of lore specifically regarding the wildlife of the realms of Tredecimos.