For years, Mikrogeophagus, a genus of dwarf South American cichlids, has been comprised of two named species – altispinosus and ramirezi. Common names for these two species are the Bolivian Ram and German Blue Ram, respectively.
Now there is a third, Mikrogeophagus maculicauda.
As described by Wolfgang Staeck, et al. (PDF) last year, this beautiful little fish naturally resembles its genus mates. However, one defining physical characteristic is the dark spot or blotch found at the base of the caudal peduncle. Hence the latin name maculicauda. Another characteristic is the feathery elongations of the caudal and dorsal fins of males. Found in the eastern portion of the upper Rio Guaporé drainage of Brazil, the species is being exported but has yet to establish a foothold in the hobby.
For more information about the maculicauda, see the paper linked above or visit its recent entry in the The Cichlidroom Companion.