Eremoryzomys

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Eremoryzomys

Data Deficient (IUCN 3.1)[1]
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Rodentia
Family: Cricetidae
Subfamily: Sigmodontinae
Genus: Eremoryzomys
Weksler, Percequillo, & Voss, 2006
Species:
E. polius
Binomial name
Eremoryzomys polius
(Osgood, 1913)
It occurs in northwestern Peru (see text for details).
Range in northern Peru[2]
Synonyms
  • Oryzomys polius Osgood, 1913[3]
  • [Eremoryzomys] polius: Weksler, Percequillo, and Voss, 2006[4]

Eremoryzomys polius, also known as the gray rice rat

Wilfred Osgood, it was originally placed in Oryzomys and named Oryzomys polius. In 2006, a cladistic analysis found that it was not closely related to Oryzomys in the strict sense or to any other oryzomyine then known, so that it is now placed in its own genus, Eremoryzomys. The Brazilian genus Drymoreomys, named in 2011, is probably the closest relative of Eremoryzomys. Eremoryzomys has a limited distribution in the dry upper valley of the Marañón River
in central Peru, but may yet contain more than one species.

A large, long-tailed rice rat, with head and body length of 138 to 164 mm (5.4 to 6.5 in), E. polius has gray fur and short ears. There are well-developed

Data Deficient"; it is poorly known but may be threatened by habitat destruction
.

Taxonomy

The first two specimens of Eremoryzomys polius were collected by

Wilfred Osgood and M.P. Anderson in 1912. The next year, Osgood described these animals as a new species in the genus Oryzomys, Oryzomys polius.[3] Osgood wrote that he was unable to find any species closely related to O. polius and compared it with O. xanthaeolus (currently Aegialomys xanthaeolus) "for convenience".[6] Its relationships remained obscure ever afterward and it was never assigned to any of the several groups of species recognized within Oryzomys.[7]

In 2006, Marcelo Weksler published a large-scale

mesoflexus (one of the valleys between the cusps and crests) divided in two.[9]

In Weksler's analysis, species placed in Oryzomys did not form a coherent (

Drymoreomys albimaculatus, was described from southeastern Brazil, and phylogenetic analysis of morphological and molecular data suggested that this animal is the closest known relative of Eremoryzomys.[13]

Eremoryzomys is now one of about 28 genera[11] in the tribe Oryzomyini, which includes well over a hundred species distributed mainly in South America, including nearby islands such as the Galápagos Islands and some of the Antilles. Oryzomyini is one of several tribes recognized within the subfamily Sigmodontinae, which encompasses hundreds of species found across South America and into southern North America. Sigmodontinae itself is the largest subfamily of the family Cricetidae, other members of which include voles, lemmings, hamsters, and deermice, all mainly from Eurasia and North America.[14]

Description

Eremoryzomys polius is a large, long-tailed rice rat that in color resembles some North American

synapomorphy of Oryzomyini.[19]

Skull

In the

braincase, especially in old animals.[4] The parietal bones form part of the roof of the braincase and, unlike in some other rice rats, also extend to the sides of the braincase.[21] The interparietal bone at the back of the braincase is narrow and wedge-shaped, so that the parietal and occipital bones meet extensively.[22]

The incisive foramina are very long, extending well between the molars. The posterolateral palatal pits are well-developed and recessed into a

tegmen tympani, the roof of the tympanic cavity, a defining character of oryzomyines.[24]

In the mandible, the mental foramen, an opening in the mandible just before the first molar, opens to the outside, not upwards as in a few other oryzomyines.[25] The upper and lower masseteric ridges, which anchor some of the chewing muscles, usually join into a single crest at a point below the first molar and do not extend forward beyond the molar.[26] There is no distinct capsular process of the lower incisor, a trait Eremoryzomys shares with only a few other oryzomyines.[27]

Molars

The

anteroconid, the front cusps on the upper and lower first molar, are not divided into smaller outer and inner cusps.[12] Small accessory roots are absent from the molars, so that each of the three upper molars has two roots on the outer side and one on the inner side and each of the lower molars has one root at the front and one at the back.[29]

Distribution and status

As far as now known, Eremoryzomys polius is confined to a small area in central Peru, at an altitude of 760 to 2,100 m (2,490 to 6,890 ft),

Data Deficient". It is threatened by habitat destruction for cattle pasture and is not known from any protected areas.[1]

Notes

  1. ^ Weksler et al., 2006, p. 10; Percequillo et al., 2011, p. 388. Weksler, 2006, table 5, scores Eremoryzomys (as Oryzomys polius) as having overlapping squamosals and maxillaries (see character state definitions for character 30, p. 32).
  2. ^ Weksler et al., 2006, p. 10. Percequillo et al., 2011, p. 367, write that the fossa does not reach between the molars in Eremoryzomys.

References

  1. ^ . Retrieved 14 November 2021.
  2. ^ Pacheco et al., 2008; Musser and Carleton, 2005, p. 1153
  3. ^ a b c d Osgood, 1913, p. 97
  4. ^ a b c d e f g h Weksler et al., 2006, p. 10
  5. ^ a b Musser and Carleton, 2005, p. 1153
  6. ^ Osgood, 1913, pp. 97–98
  7. ^ Weksler, 2006, table 2, p. 130; Musser and Carleton, 2005, pp. 1144, 1158
  8. ^ Weksler, 2006, figs. 34–40
  9. ^ Weksler, 2006, p. 130
  10. ^ Weksler, 2006, pp. 75, 77, fig. 42
  11. ^ a b Weksler et al., 2006, p. 1
  12. ^ a b c Weksler et al., 2006, p. 11
  13. ^ Percequillo et al., 2011, p. 372
  14. ^ Musser and Carleton, 2005
  15. ^ Weksler, 2006, p. 24
  16. ^ Weksler, 2006, p. 17, table 5
  17. ^ Weksler, 2006, table 8
  18. ^ Steppan, 1995, table 5
  19. ^ Weksler, 2006, p. 52
  20. ^ Weksler, 2006, pp. 27–28, table 5
  21. ^ Weksler, 2006, p. 30
  22. ^ Weksler, 2006, p. 31
  23. ^ Weksler, 2006, pp. 38–39; Weksler et al., 2006, p. 10
  24. ^ Weksler, 2006, p. 40
  25. ^ Weksler, 2006, p. 41, table 5
  26. ^ Weksler, 2006, p. 44; Weksler et al., 2006, p. 11
  27. ^ Weksler, 2006, pp. 41–42; Weksler et al., 2006, p. 11
  28. ^ Weksler, 2006, pp. 43–44
  29. ^ Weksler, 2006, p. 43; Weksler et al., 2006, p. 11
  30. ^ Percequillo et al., 2011, p. 378
  31. ^ Musser and Carleton, 2005, p. 1153; Pacheco et al., 2008
  32. ^ Percequillo et al., 2011, p. 379

Literature cited