Rattus exulans (Peale, 1848)

Pine, Ronald H., Mack, Andrew L. & Timm, Robert M., 2017, Marsupials And Rodents Of The Admiralty Islands, Papua New Guinea, Occasional Papers of the Museum 352, pp. 1-30 : 22

Rattus exulans (Peale, 1848)

Pacific Rat

Thomas (1914:439) reported three specimens of “ Epimys browni ” from “ Manus Island.” Taylor et al. (1982), referring to these same three specimens, recorded them as from “ Manus Is., 5 m, 02°04′S, 147°00′E,” treated them as members of Rattus exulans browni (Alston, 1877) , and gave their catalog numbers as BMNH 14.4.1.18–14.4.1.20. Owing to the known recent past and assumed present mobility of this commensal species, we do not recognize subspecies.

Williams (1999) did not report R. exulans as having been found at the Pamwak archeological site on Manus, but T. F. Flannery (in litt.) states that he did find this species in remains from there. Although Aplin et al. (2015:51) stated that Flannery (1995b) reported R. exulans from the Pamwak site, this is not the case.

Aplin et al. (2015:57) reported having caught 13 specimens in 2014, encountering this species in a variety of habitats on Manus, noting “They appeared to be most numerous in the garden and village habitats, and to be relatively scarce in the natural forest.” This is not surprising in view of the commensal nature of this species. In addition to trapped individuals, visual sightings and camera trap records were also recorded.

We here report five additional trapped specimens, housed at the University of Kansas. These are KU ♂ 163725 and KU ♀ 163726 from Manus, without more precise known locality and taken by unidentified collectors ; KU ♂ 163727 from “ Tulu 1” at 1°57.371′S, 146°50.282′E, 34 m; and KU ♂♂ 163788, 163929 from Manus but from no named locality at 2°0.102′S, 146°48.634′E. Elevation for 163729 was 31 m.

In addition to the specimens at the University of Kansas, there are two specimens in the collection of PNGMAG, identified as belonging to that species and from the Admiralties. These are PNGMAG 22514 from “ Airie Base Camp ” with the nearest village given as Pelikawa (2°12′0″S, 146°55′59″E or 2.2°S, 146.933°E—but see locality information for next specimen), on Manus, said to be a flat skin but preserved in “75% alcohol,” specimen not seen ; PNGMAG 22477 from “ Airie ” [apparently = Aerie Camp or Airie Camp at 2°07′S, 146°42′E —see Bonaccorso (1998:427)], images of study skin and skull seen . PNGMAG 22477 , on the basis of photographs, seems to have atypical coloration for R. exulans , being unusually reddish dorsally but with an apparently unremarkable gray-based venter with broadly cream-colored tips . The skull appears to be that of an R. exulans , however, in shape, size, and dentition. Taylor et al. (1982:277) stated that the quality and color of the pelage of R. e. browni are “highly variable.” However, they stated unequivocally (p. 278) that the ventral fur is gray-based.

The affinities of the exulans on Manus might warrant further study. Although the upper toothrow lengths of the KU specimens fit within the range given by Taylor et al. (1982), there is considerable variation in tooth size in these Manus specimens. The teeth of immature 163728 are especially large, compared to those of the other specimens from there.