Thomasomys ucucha

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Thomasomys ucucha
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Rodentia
Family: Cricetidae
Subfamily: Sigmodontinae
Genus: Thomasomys
Species:
T. ucucha
Binomial name
Thomasomys ucucha
Voss, 2003
The species is known from a single site in north-central Ecuador.

Thomasomys ucucha, also known as the ucucha thomasomys,

T. hylophilus, which occurs further to the north. The species is listed as "vulnerable" in the IUCN Red List as a result of habitat destruction
.

Medium-sized, dark-furred, and long-tailed, T. ucucha can be distinguished from all other species of Thomasomys by its large, broad,

incisive foramina, openings at the front of the palate, are short, and the palate itself is broad and smooth. The root of the lower incisor is contained in a prominent capsular process
.

Taxonomy

The first three specimens of Thomasomys ucucha were collected in 1903 at

T. silvestris, but T. hylophilus was not included in this study.[7] All are members of Thomasomys, a diverse genus that occurs in the northern Andes, from Bolivia to Venezuela.[8] Together with Rhipidomys and a few other, smaller genera, Thomasomys forms the tribe Thomasomyini, which includes over fifty species found in South America and Panama. Thomasomyini in turn is part of the subfamily Sigmodontinae of the family Cricetidae, along with hundreds of other species of mainly small rodents.[9]

Description

Thomasomys ucucha is a medium-sized Thomasomys with a relatively long tail. The dense, fine, and soft fur is dark brown on the upperparts, changing gradually into the grey underparts. The mystacial

mammae.[10] In thirty-six specimens, head and body length is 94 to 119 mm (3.7 to 4.7 in), averaging 110 mm (4.3 in); tail length is 122 to 151 mm (4.8 to 5.9 in), averaging 140 mm (5.5 in); hindfoot length is 26 to 30 mm (1.0 to 1.2 in), averaging 28 mm (1.1 in); ear length is 17 to 20 mm (0.67 to 0.79 in), averaging 18 mm (0.71 in); and weight is 24 to 46 g (0.85 to 1.62 oz), averaging 36 g (1.3 oz).[11]

The front (rostral) part of the

braincase is robust.[10]

The

tegmen tympani, the roof of the tympanic cavity, overlaps the suspensory process of the squamosal bone. At the back of the mandible (lower jaw), there is a capsular process to receive the root of the lower incisor,[10] which is absent in T. hylophilus.[12]

The large upper incisors are

anteroconid (the equivalent of the anterocone on the first lower molar) is often undivided and the third molar is unreduced.[10]

The glans penis is rounded, short, and small and is superficially divided into left and right halves by a trough at the top and a ridge at the bottom. Most of the glans is covered with penile spines, except for an area near the tip.[10]

Distribution and ecology

Thomasomys ucucha occurs only in the

sympatrically with seven other species of Thomasomys.[8] With Akodon latebricola and Thomasomys erro, T. ucucha is one of three species that are known only from the northeastern Andes of Ecuador.[18]

Conservation status

Thomasomys ucucha is locally common, but has a very limited known distribution.

IUCN because of its highly localized distribution; it may be threatened by the destruction of its habitat for agricultural purposes,[1] but occurs near or in several protected areas.[19][15]

References

  1. ^
    doi:10.2305/IUCN.UK.2018-1.RLTS.T136487A22366894.en
    . Retrieved 19 November 2021.
  2. ^ Musser and Carleton, 2005, p. 1184
  3. ^ a b c d e Voss, 2003, p. 10
  4. ^ a b Voss, 2003, p. 2
  5. ^ Beolens et al., 2009, pp. 410–411
  6. ^ Voss, 2003, p. 12
  7. ^ Lee et al., 2015, fig. 2
  8. ^ a b Voss, 2003, p. 8
  9. ^ Musser and Carleton, 2005
  10. ^ a b c d e f g h Voss, 2003, p. 11
  11. ^ Voss, 2003, table 1
  12. ^ a b c d e f Voss, 2003, p. 13
  13. ^ Voss, 2003, table 2
  14. ^ a b Voss, 2003, p. 14
  15. ^ a b c Lee et al., 2015, p. 7
  16. ^ Voss, 2003, pp. 14–15
  17. ^ Voss, 2003, p. 15
  18. ^ Voss, 2003, p. 37
  19. ^ a b Tirira, 2007, p. 198

Literature cited

External sources

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