Nectomys Peters, 1861

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 : 54-55

Nectomys Peters, 1861

Species of Nectomys , commonly known as water rats, are distinctively large (> 150 g) amphibious cricetids that occur in or near streams and rivers throughout much of tropical and subtropical South America below about 2500 m. Five species are currently recognized ( Bonvicino and Weksler, 2015), of which two occur in the Yavarí-Ucayali interfluve. Water rats have glossy-brownish or -blackish-brown dorsal fur; gray-based buffy ventral fur; small ears (not reaching the eye when laid forward); long, macroscopically naked, unicolored (all dark) tails; and large hindfeet with small interdigital webs (not extending distally beyond the ends of the first phalanges), naked claws (not concealed by ungual tufts), and visibly scaly soles. Water rat skulls have deep zygomatic notches; anteriorly convergent interorbital regions with well-developed supraorbital beads; long palates; well-developed, complex, and deeply recessed posterolateral palatal pits; and derived carotid circulations (pattern 3 of Voss, 1988). There is usually a notch in the posterolateral margin of the squamosal that is homologous with the subsquamosal fenestra of other Neotropical cricetids, but the fenestra itself is not patent. The molars are higher crowned than those of most other oryzomyines, pentalophodont (with well-developed mesolophs and mesolophids), and lophodont (with interpenetrating lingual and labial flexi). Morphological comparisons with the closely related genus Amphinectomys have already been discussed in the account for A. savamis (above) with the most conspicuous contrasts summarized in table 9.

ETHNOBIOLOGY: The Matses do not recognize more than a single species of water rat in their tribal territory, but the specimens we collected in the vicinity of Nuevo San Juan are all Nectomys apicalis , so our ethnographic information is summarized in the following account.