. Bonner zoologische Beiträge : Herausgeber: Zoologisches Forschungsinstitut und Museum Alexander Koenig, Bonn. Biology; Zoology. Small mammals from forest islands 405 Length of upper molars o o o o o o — — J Width of M1 Fig. 3: Bivariate plot of "Width of Ml" versus "Length of upper molars" for Praomys h. hart- wigi (n = 33) and P. h. obscuras n. ssp. (n = 32); all ages and both sexes combined. slightly smaller than in hortwigi (Table 2). Differences exist in the greatest length of skull, mastoid width, crown length of upper toothrow, and w
. Bonner zoologische Beiträge : Herausgeber: Zoologisches Forschungsinstitut und Museum Alexander Koenig, Bonn. Biology; Zoology. Small mammals from forest islands 405 Length of upper molars o o o o o o — — J Width of M1 Fig. 3: Bivariate plot of "Width of Ml" versus "Length of upper molars" for Praomys h. hart- wigi (n = 33) and P. h. obscuras n. ssp. (n = 32); all ages and both sexes combined. slightly smaller than in hortwigi (Table 2). Differences exist in the greatest length of skull, mastoid width, crown length of upper toothrow, and width of first upper molar (Figs 2, 3). The molars not only differ in size but also in the crown pattern (Fig. 2). While some show the "typical" hartwigi pattern with only tl and t2 present at the first upper molar, 13 out of 33 specimens have at least traces of a t3 (Fig. 2 G), in some cases more than that (Fig. 2 K). Also, the arrangement of the first transverse laminae is strongly angular in hartwigi (Fig. 2 A—E) and less so in obscurus (Fig. 2 F—K). This also counts for the second lamina of the first and se- cond molar, giving obscurus a less "stephanodont" aspect. Discussion: With the present material at hand w^e cannot make a clear decision whether obscurus represents a subspecies of hartwigi (a view^ favoured by Dieterlen) or a different species (the view favoured by Hutterer). Both populations are separated by a distance of about 100 km and have not been found to occur in sympatry yet, which seems unhkely as both live in isolated forests on different plateaus. The mor- phological differences are obvious. However, within the genus Praomys both hartwigi and obscurus share a similarly long pelage, large body size, large molars, and similar skuh proportions. Erik Van der Straeten (Antwerp), whom we consulted during our study, kindly performed a principal compound analysis with measurements he had taken from our specimens. His results are equally
Size: 2346px × 1065px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookcoll, booksubjectbiology, booksubjectzoology
