Proechimys quadruplicatus Hershkovitz, 1948

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 : 141-143

Proechimys quadruplicatus Hershkovitz, 1948

Figures 57A, 57D

VOUCHER MATERIAL (N = 51): El Chino (MVZ 198518, 198534; UF 30720–30735, 30737– 30752), Orosa (AMNH 73801–73814), San Pedro (UF 30615, 30657, 30736).

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

IDENTIFICATION: Proechimys quadruplicatus is a large species that, in our region, has unremarkably brownish dorsal pelage—near Ridgway’s (1912) Dresden Brown or Snuff Brown—and abruptly pure-white ventral pelage. The ventral fur is somewhat denser and softer than those of most (but not all) other species in the region. The hind feet are distinctly bicolored in most specimens, with whitish hairs over the medial metatarsals and brownish hairs over the lateral aspect of the foot. The baculum is small in proportion to body size (9.2 mm in length and 3.3 mm in proximal width, on average, in three fully mature specimens), with weakly developed apical processes and an average width-to-length ratio of 0.35 (range = 0.33–0.37).

The incisive foramina are lyrate, weakly so in most examined specimens, but sometimes strongly; one specimen ( AMNH 73807 ), however, has more or less oval foramina, and another ( UF 30750 ) has foramina with subparallel margins. The incisive septum is complete in only about half the specimens we examined. The premaxillary part of the septum is usually short, and the vomerine portion is usually concealed, whereas the maxillary process is usually long, slender, and strongly keeled. The anterior palate is grooved in most specimens (strongly grooved in some), but it is more or less smooth in others (e.g., AMNH 73808). The mesopterygoid fossa always penetrates at least between the third molars and often between the second molars, resulting in an average mesopterygoid penetration score of 2.8 (range = 2–4). The floor of the infraorbital foramen often has a distinct groove for the infraorbital nerve, but it is occasionally quite smooth (e.g., in AMNH 73813). The temporal crest usually extends onto the parietals, sometimes for only a short distance, but often to a point just above the postglenoid foramen. Almost all lightly worn upper cheekteeth have four labial folds, although the posteriormost fold is often lost with advancing toothwear ; the sample formula for our sample (based on minimally worn teeth) appears to be 4-4-4(3)-4(3). Craniodental measurements of our specimens (table 41) broadly overlap those of Hershkovitz’s (1948) type series from eastern Ecuador .

The specimens from Orosa were identified by Patton and Leite (2015) as Proechimys steerei , but they are morphologically indistinguishable from the El Chino specimens that those authors referred to P. quadruplicatus . Although El Chino is south of the Amazon, Patton and Leite (2015: map 522) plotted this locality on the north bank of the river, an obvious lapsus. Proechimys quadruplicatus and P. steerei —both members of the Goeldii Group—are morphologically similar, but the mtDNA clades that we associate with these names (fig. 54, table 38) are vouchered by specimens that differ in external and dental characteristics. Whereas specimens of P. quadruplicatus (e.g., those from El Chino and Orosa) have drabbrownish dorsal fur, the specimens we identify as P. steerei (from Nuevo San Juan) have brighter, reddish-brown dorsal fur. Additionally, the predominance of 4-4-4-4 labial folds in the upper cheekteeth of both the El Chino and Orosa series ( P. quadruplicatus ) contrasts with our observation of 3-3-4-3 folds in the series from Nuevo San Juan ( P. steerei ). The diagnostic value of frequency differences that we observed in several other characters (table 39) are hard to interpret as taxonomic evidence due to the small size of our P. steerei sample (comprising only four adults; see below).

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

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

REMARKS: None of the specimens of Proechimys quadruplicatus from our region are accompanied by habitat information, but the series from Orosa was probably collected in várzea, which extends inland for several kilometers at this riverside locality ( Wiley, 2010). According to Valqui (2001) —most of whose voucher specimens (at the UF) were correctly identified— this species is “a strict várzea specialist ... it is the only spiny rat species in true seasonally flooded forest, especially in areas far from terra firme habitats.”