The dalmatian gene in isopods is possibly the most popular variety to keep. Initially, it was only available in a couple species, P. laevis and P. scaber, but has since developed and been isolated in a variety of additional species.
So, what is the dalmatian gene? Dalmatian is a recessive gene that affects the patterning of an animal. It does not change the color, but causes an absence of pigments, allowing color to appear only in spots. The gene expresses differently depending on the species, which may be due to a mix of the original stock it was isolated from and the way the gene interacts with that specific species. Dalmatian can be slightly frustrating to work with, because members expressing this trait are born patternless and gain spots as they age.
P. laevis "dairy cow"
Porcellio laevis is most well known for its variation of the dalmatian, known as "dairy cow". It does go by other names: in Germany it is commonly called "panda" and other parts of Europe even call it "dalmatian", although some keepers insist this is only given to laevis that have smaller spots. "Dairy cow" is a world wide term that keepers use throughout the trade, so this is what is most encouraged to use when discussing it in laevis. Porcellio laevis reach impressive sizes, typically 1.5cm, making them very popular because their large sizes makes the patterning even more observable. Laevis retains a heavily spotty population, some even being so saturated they border melanistic.
P. laevis "white"
Another mutation has been isolated from "dairy cow" called "white". This expression of the gene has minimal spotting, at most a few flecks, to create an almost entirely white population. An interesting aspect is that "dairy cow" laevis cannot breed with other mutations of laevis; whether it is orange, wild type, etc. It is theorized that the dalmatian mutation has made their genitalia incompatible.
P. scaber "dalmatian"
The next most well known expression of the mutation is "dalmatian" in P. scaber. Unfortunately, this species is known for regressing its pattern and trending towards a patternless population. There are a couple of theories as to why this may happen: the first being that high temps encourage low pattern; however when kept as low at 62F animals still trend to patternless. The next theory is that a shallow gene pool encourages patternless individuals, and there may be some truth to this one. Many keepers have had success out-crossing with other mutations and introducing fresh bloodlines from other dalmatian cultures. An additional method that can be used is linebreeding the culture back to a more patterned trend. This method won't prevent the low patterns from occurring completely, but encourages the population to trend to be more spotty.
The dalmatian gene in P. scaber has also been crossed to other mutations, most notably "Spanish orange". The result is "orange dalmatian", a great demonstration of the two genes. The more speckled dalmatians are also theorized to be a cross with the calico gene; the theory is the calico causes breaks in the spotting creating a speckled appearance. With all the scaber morphs available in the hobby, it will be interesting to see what is produced next!
Armadillidium vulgare "Japanese magic potion"
The next species well known for dalmatian spotting is A. vulgare. Dalmatian spotting in this species was given the name "magic potion", due to the unique appearance of black and yellow spots. The dalmatian gene only affects the dark pigment in isopods, so the natural yellow spotting in vulgare is layered with the dark spots. Magic potion is interesting in that there are actually two separate places that it has been isolated; in America and Japan. The American variety was isolated first, and the Japanese followed a year or two later, completely independently of the first. The Japanese variety is reportedly smaller, but reproduces much more quickly. The American line is also have said to have a much more spotty pattern than the Japanese.
Armadillidium vulgare "orange dalmatian"
The American line of magic potion has also produced another mutation. Rather than black spots, the spots on this line are orange! It is believed to be a spontaneous mutation, but it is not outside the realm of possibility that an orange vulgare crossbred with American magic potions.
Armadillidium nasatum "pearl"
Armadillidium nasatum also has a variation of dalmatian; but just barely. This expression of the dalmatian gene is a strange one in that is is only expressed in about 10% of males in the culture, making it a male sex-linked gene. Some other members of the culture have flecks of pigment but the majority of the culture is patternless with a base color of either beige or white.
An additional dalmatian mutation available in the US is from the species Oniscus asellus. This species also has natural yellow spotting- this spotting increases in size and brightness as the animals age. The name for this mutation is "Mardi Gras dalmatian" due to the differently colored appearance. This strain of dalmatian presents in quite a variety of ways; some specimens present with an almost striped appearance. Some cultures also produce "piebald" individuals, where there is a lack of patterning and the rest appears normal.
There is also a species of Cubaris that presents with spotting similar to dalmatian, Cubaris sp. "Shiro Utsuri". However, this was collected, not isolated, so it is considered a locale and representation of the species, not a mutation. We don't currently have this species in our possession so we don't have photos to link in this blog.
Additional species not available in the US presenting the dalmatian mutation are Armadillidium granulatum and Armadillidium depressum. These species are dark, with natural yellow spotting and the mutation presents similarly to Armadillidium vulgare. They have both been given the name "magic potion" due to the similarities.
Dalmatian is an exciting mutation that is cute and resents with many possibilities. People enjoy keeping dalmatian both due to the genetic possibilities and as a pet to observe.