Proechimys cuvieri Petter, 1978

Voss, Robert S., Fleck, David W. & Jansa, Sharon A., 2019, Mammalian Diversity And Matses Ethnomammalogy In Amazonian Peru Part 5. Rodents, Bulletin of the American Museum of Natural History 2024 (466), pp. 1-180 : 139-140

Proechimys cuvieri Petter, 1978

Figures 56B, 56E

VOUCHER MATERIAL (N = 38): Nuevo San Juan (MUSM 11259, 11263, 11266, 11271, 11308, 11309), Orosa (AMNH 73792–73800, 74089– 74092), San Pedro (UF 30558, 30559, 30561, 30563, 30565, 30567–30572, 30574, 30577, 30788; MVZ 198511), Siete de Julio (30576, 30780, 30782, 30783).

UNVOUCHERED OBSERVATIONS: Field identifications of this species cannot be accepted as valid without supporting voucher material.

IDENTIFICATION: Proechimys cuvieri is another medium-sized species, indistinguishable in external and craniodental dimensions from P. brevicauda (table 40), which it likewise resembles in most qualitative morphological traits. The dorsal pelage is brownish—like the dorsal pelage of most sympatric congeners ( P. steerei , with distinctively reddish-brown dorsal pelage, is the unique exception; see below)—but in side by side comparisons it appears more coarsely grizzled and has broader and stiffer spines than those of P. brevicauda . The ventral pelage is entirely white

41 Despite the abundance of Proechimys species in our region, ecological information summarized in these accounts is limited because many MUSM specimens were preserved in fluid, and their skulls have yet to be extracted and cleaned; these specimens could not be confidently identified to species, nor were we able to confidently identify all juvenile specimens among those with cleaned cranial material.

in some specimens (e.g., AMNH 74090, MUSM 11263), but it is marked with pale brown—especially on the throat and laterally—in others (AMNH 73797, 73798, 73800). The ventral fur is thin and feels harsh to the touch because it consists mostly of soft spines with only a few wool hairs mixed among them. Most specimens have brownish dorsal fur on the hind feet, which do not differ conspicuously in coloration from those of P. brevicauda based on the material we examined. By contrast, the baculum (which we examined from eight specimens) is diagnostically short (6.8 mm, on average), broad (5.7 mm proximally), and deeply forked ( Patton et al., 2000: fig. 137), with an average ratio of basal width to length of about 0.94 (range = 0.74–1.18), quite unlike the bacular morphology of other spiny rats in our region.

Distinctive craniodental traits of Proechimys cuvieri include consistently strongly lyrate incisive foramina from which shallow grooves extend onto the posterior part of the diastema but usually not between the premolars, resulting in an ungrooved (or very weakly grooved) and usually ridgeless anterior palate. The incisive septum is complete, with a long premaxillary portion and a short maxillary portion that is not strongly keeled in any specimen we examined; the vomer is usually at least partially exposed. The mesopterygoid fossa always extends between the third molars, often deeply (mean score for this character = 2.5, range = 2–3). The floor of the infraorbital foramen is usually smooth (range of scores = 1–1.5), and the temporal crest usually lacks a distinct parietal extension, although more or less distinct extensions of variable length occur in a few specimens (e.g., AMNH 73796, 73797). The first two upper cheekteeth have only three labial folds, but M2 usually has four, and M3 sometimes also does, resulting in a sample formula of 3-3-4(3)-3(4).

Our specimens correspond closely to Patton and Leite’s (2015: 974) qualitative description of Proechimys cuvieri , although the ventral pelage of our specimens (as previously noted) is sometimes marked with pale brown and the hind feet are usually brownish, such that this species cannot be distinguished consistently from P. brevicauda based on pelage coloration, at least in our region. Additionally, whereas Patton and Leite describe this species as typically having three labial folds on each upper cheektooth, M2 usually—in 13 of 17 specimens we scored for this character—has four labial folds in our material.

Measurements of our series (table 40) closely resemble those of topotypical specimens of Proechimys cuvieri (from French Guiana; Voss et al., 2001: table 45) despite substantial mtDNA (cytochrome b) divergence among geographic populations of this widespread species ( Patton and Leite, 2015) or species complex ( Dalapicolla et al., 2024). Measurements of our series also resemble those of P. cuvieri from the Rio Juruá as reported by Patton et al. (2000: table 64), with the unique exception of mean condyloincisive length (CIL), for which Patton et al.’s sample differs from ours by more than two standard deviations, an obvious lapsus. 42 As previously noted by Voss et al. (2001), there are substantial differences in cranial trait frequencies among geographic populations of P. cuvieri , but morphological differences have yet to be convincingly correlated with mtDNA clade membership, so their taxonomic relevance is unclear.

ETHNOBIOLOGY: The Matses have no special name for this species.

MATSES NATURAL HISTORY: No interviews were focused on this species.

REMARKS: Six specimens of Proechimys cuvieri from Nuevo San Juan are accompanied by habitat information. Of these, three were trapped in upland primary forest and three were trapped in swiddens ; all recorded captures were made in traps set on the ground. By contrast, the 13 specimens from Orosa were almost

42 The mean value for CIL in the Juruá series according to Patton et al.’s (2000) table 64 is 39.6 mm, which is the same value as the sample minimum provided in the next column. Most of the Juruá series has been returned to Brazil, but the mean value for CIL computed from measurements of 10 specimens remaining at the MVZ is 45.6 mm (J.L. Patton, personal commun.), which is very close to the corresponding mean in our series.

certainly taken in várzea, which extends for several kilometers inland from this riverside locality ( Wiley, 2010). According to Valqui (2001) —most of whose voucher specimens (at the UF) were correctly identified—this species was found to be “restricted to streambeds of small to medium size streams of primary terra firme forest, where they are often the most abundant spiny rat.” The lack of consistency in these data suggest that P. cuvieri is a habitat generalist, at least in our region.