After a short notice upon its author, whose scientific works are presently rather unknown, we publish the first complete translation in French language of the original description of the extinct Holocene Hippopotamus madagascariensis Guldberg, 1883, which was published in Riksmaal, an ancient Norvegian language incomprehensible for most palaeontologists. We provide a mammalogical comment of that description, showing that the Guldberg’s specimen actually pertains to the other small species of Holocene Malagasy hippo, Hippopotamus lemerlei Grandidier, 1868. Since Guldberg’s publication, that initial confusion was spread in many scientific works and has important taxonomical consequences. Thus, in 1902, C. J. F. Major described under the name H. madagascariensis Guldberg, 1883 a new Malagasy skeleton which is quite different from H. lemerlei. But because H. madagascariensis is no more than a replacement name for H. lemerlei, it is not usable. We then propose the new name Hippopotamus guldbergi to designate the species described in 1902 by C. J. F. Major.
Mammalia, Hippopotamus madagascariensis, Madagascar, Holocene, new species.