Luzon Montane Forest Mouse - Discovery

Discovery

The Luzon montane forest mouse was the first species of Apomys ever to be discovered. In 1895, an expedition was organised which brought to Europe the first specimens of several genera, including Carpomys, Rhynchomys and Crunomys. During this expedition, in February, England explorer John Whitehead captured a number of unknown rats on a site called Lepanto on Mount Data, at an altitude of approximately 2,500 m (8,200 ft). In 1898, British biologist Oldfield Thomas described these animals as an "interesting species", but identified them as Mus chrysocomus, a species from Sulawesi that is now known as yellow-haired hill rat (Bunomys chrysocomus) and reckoned among the genus Bunomys, which is not actually closely related to Apomys. Thomas sent a specimen to the Staatliches Museum für Tierkunde Dresden, where Adolf Bernard Meyer concluded that the animal did not resemble Mus chrysocomus. Meyer described th animal as Mus datae in 1899, after its type locality – Mount Data (at the time the generic name Mus was used more broadly than it is now). For a long time, little was known about Mus datae, until 1913, when American biologist Ned Hollister described eight rats from Luzon under the name Epimys datae ("Epimys" was the name of the genus that would later become Rattus). These were in fact examples of the Himalayan field rat (Rattus nitidus), but they were only identified as such in 1977, by Guy Musser, another American biologist. Meanwhile, in Britain, John Ellerman had finally placed Mus datae with its relatives in Apomys, in 1941. Eleven years later, in 1952, American zoologist Colin Campbell Sanborn announced that he had captured 54 specimens of A. datae on Mount Data. A good part of this catch, however, was later found to consist of specimens of the Luzon Cordillera forest mouse (A. abrae), a species which had been described by Sanborn in the same article in which he had made his announcement.

In a 1982 article, Musser defined the genus Apomys and gave the first modern description of A. datae, while also correcting Sanborn's mistake in the identification of his collection. It was revealed that Sanborn had not been the only one to get the major species of Apomys from Luzon cofused: the holotype of the species Apomys Major, described by Gerrit Smith Miller of the Smithsonian Institution in 1910, turned out to have been a specimen of A. datae, while the other animals to have been identified as A. major were discovered to be examples of A. abrae. Since that time, Apomys major has been considered a subjective synonym of A. datae. Musser identified A. datae as the only member of the "Apomys datae group" within the genus, being different from all other species. In 1993 and 1994, the species was observed in the Sierra Madre, at an altitude between 760 and 1,650 m (2,490 and 5,410 ft), but this probably concerns a population of a separate, undescribed species. A second species within the A. datae group was described by Luis Ruedas, in 1995: Apomys gracilirostris. In the 21st century, the knowledge about A. datae was expanded with data from genetic research. In 2002, the karyotype was revealed, and in 2003, the phylogenetic relationship with A. gracilirostris was confirmed, based on common features in the species' DNA. Most recently, the animal has been found on several new locations in North Luzon.