New data on comparative morphology and distribution of spiny rats Proechimys cuvieri and P-cayennensis (Echimyidae : Mammalia) in french Guyana

A collection of 160 preserved specimens of Proechimys spp. (Echimyidae: Rod entia) originating from French Guiana was studied morphologically in order to improve the knowledge on the co-occurrence of P. cuvieri and P. cayennen sis. By using morphological criteria proposed by Patton (1987), 134 P. cuvi eri Fetter, 1978 and 26 P. cayennensis (Desmarest, 1817) were recognized, c onfirming that the largest species is the most abundant. Terrestrial spiny rats come from 18 localities in French Guiana, covering d ifferent environments (primary and secondary forests, as well as open savan nah regions). Both species were found together in syntopy in a few localiti es (Nouragues, Saint-Eugene, Petit-Saut, Piste Saint-Elie), and they appear largely sympatric at a regional scale. External measurements show a large overlap of values, and do not allow to r ecognize each species, whereas the crown lengths of upper molars appear to be species-specific, whatever the age of the animals. Tables of external an d cranial measurements are provided for animals sorted into four classes of age, as the post-weaning growth is particularly important in Proechimys.