The Amazing Volcano Rabbit

I've been reading up on this critter for the past few days, ever since I pulled out some old mammal texts I had sitting on the shelf. I got sucked in and thought I would share a bit of what I've read.

The volcano rabbit, Romerolagus diazi, is found on the slopes of only four volcanoes in Mexico, south of Mexico city. These four - Pelado, Iztacohuat, Tlaloc and Popocatepetl - are part of the transvolcanic belt (TVB; also called the trans-Mexican volcanic or transverse neovolvanic belt), a biogeographic zone in the center of the country that exhibits a high level of endemism; in other words, there is a large number of organisms in the TVB that are unique to that area.

Volcano rabbits look like pikas with slightly exaggerated features - short ears, short legs and vestigial tails. Their dark, mottled coats blend with the bare basaltic rock and exposed volcanic soil. They're also one of the smallest rabbits in the world, second only to the pygmy.

Rabbits, or lagomorphs, were lumped in with the rodents (order Rodentia) until 1912, when J.W. Gidley created a new order for them. Unlike rodents, lagomorphs have a pair of "peg teeth", incisors that sit snugly behind their primary, ever-growing teeth (not to mention several other distinguishing features). In recent years, molecular data has shown that lagomorphs are indeed very closely related to rodents, though they retain their separate classification.

Pikas (Ochotonids) split from rabbits and hares (Leporids) about 35 million years ago in Asia, eventually differentiating into many forms, including a now extinct genus, Prolagus. In the late Pleistocene leading into the present period, the Holocene, there was an unprecedented and relatively rapid diversification of certain Leporids.

Why is that significant? Because the volcano rabbits were not a part of this later, rapid diversification, as you can see in the figure above. Some experts believe that they may be the most basal Leporid alive, but nevertheless a descendant of the first known rabbit, Alilepus.

Unfortunately, the volcano rabbit's habitat is terribly fragmented by barrier habitats and freeways. They are isolated in pine forests, roughly one to two miles in elevation, relying on the thick undergrowth of bunch grass habitat called "zacaton" for shelter and food.

The zacaton and the entire TVB is threatened by human influences. These areas are burned to clear more land for agriculture and livestock. Quite plainly, more research needs to be done not only on this area as a while, but on its individual inhabitants. There are only a handful of papers on the volcano rabbit despite its obvious uniqueness. Fortunately, the IUCN is working on a plan to protect and preserve the TVB and its special inhabitants.