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Cloud-dwelling spiny pocket mouse

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Cloud-dwelling spiny pocket mouse
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Rodentia
Family: Heteromyidae
Genus: Heteromys
Species:
H. nubicolens
Binomial name
Heteromys nubicolens
Anderson, 2006[1]

The cloud-dwelling spiny pocket mouse (Heteromys nubicolens) is a species of rodent (Rodentia) that is endemic to the high elevations of Cordillera de Tilarán and Cordillera de Guanacaste within Costa Rica.[2] It is contained within the Heteromys desmarestianus species complex.[2]

Taxonomy and Etymology

The cloud-dwelling spiny pocket mouse (Heteromys nubicolens) is contained within the subfamily Heteromyinae (spiny pocket mice), which represents a monophyletic grouping within the rodent family Heteromyidae.[2][3][4] It was officially designated as a species in 2006 and is in valid taxonomic standing with the Integrated Taxonomic Information System (ITIS).[2] This mouse gets both its common and scientific name from its range distribution within the cloud forests of northwestern Costa Rica.[2] Nubicolens, or cloud-dwelling, is derived from the Lain nubes (cloud) and colo (dwell or inhabit).[2]

Originally, H. nubicolens was thought to be contained within Heteromys desmarestianus.[2] However, recent morphological, karyological, and genetic information has revealed that H. desmarestianus represents a species complex consisting of at least 11 distinct haplotype groups.[2][5] Three of these haplotypes have been designated as unique species--Heteromys goldmani, Heteromys oresterus, and H. nubicolens--while the remaining eight are thought to represent variants of H. desmarestianus due to geographical variation.[5] Limited taxonomic sampling has prevented the complete determination of phylogenetic relationships within the Heteromys genus.[2][5]

Description

Fur Coloration and Texture

The dorsal fur of the cloud-dwelling spiny pocket mouse is dark brown, with faint grizzling and thin ochraceous hairs intermixed among spines.[2] The grizzling is less pronounced along the midline, creating a slight dark dorsal stripe.[2] The ventral fur is pure white and lacks spines.[2] Their ears are dark brown to grey and their tail is strongly bicoloured along most of its length but becomes uniformly dark at the distal end.[2] Limb coloration extends from the body coloration, with dorsal surfaces exhibiting dark fur and ventral surfaces exhibiting white fur.[2]

Morphology

H. nubicolens ranges in length from 291 mm to 358 mm with head-to-tail length ranging from 104 mm to 183 mm.[2] Its mass ranges from 60 g to 136 g.[2] The tail length is typically longer than the head-to-body length.[2] Its hind feet are relatively large with a naked planar surface.[2] It has a dental formula of I1/1, C0/0, P1/1, M3/3, totaling 20 teeth.[2] More detailed measurement and cranial morphology information can be found in Anderson and Timm (2006).[2]

Geographical Variation

Within the genus Heteromys, it has been noted that lower elevation populations sometimes exhibit increased spininess than higher elevation populations.[6][7] However, it is not certain whether this trend is also seen in H. nubicolens.

Comparisons to Similar Species

Due to their close geographic range and phylogenetic relatedness, H. nubicolens is most easily confused with H. desmarestianus.[2] Outwardly, the two species are nearly identical with both displaying dark brown dorsal fur and white ventral fur.[2] However, H. nubicolens can be differentiated by its larger size and distinct cranial morphology.[2] On average, H. nubicolens exhibits larger cranial proportions than H. desmarestianus; however, H. desmarestianus exhibits a wider interorbital distance and braincase (for more detailed differences in cranial morphology, see Anderson and Timm, 2006).[2] In Peñas Blancas Valley where the two species are thought to overlap, H. desmarestianus has pronounced ochraceous hairs around the neck region, creating a 'collar' of sorts that can also be used to differentiate it from H. nubicolens.[2]

Alongside size and cranial morphology, H. nubicolens also differs from H. desmarestianus and other species within this complex by the absence of an ochraceous lateral line, less grizzling in the fur, a larger tail to head-and-body length, and the presence of a grey dorsal stripe due to a reduction in ochraceous hairs along the midline.[2] However, none of these features are distinctive enough to allow for a confident identification.[2]

In comparison to other species within Heteromys, the dark brown grizzled fur of H. nubicolens helps differentiate it from most other species which typically possess either pale brown grizzled fur or slate grey fur that lacks grizzling.[2] Further, size and cranial features, along with distinct geographic ranges can be helpful in distinguishing between species within Heteromys.[2]

Hybridization

No interspecies hybridization has been confirmed in H. nubicolens. However, two specimens collected near Río Colorado exhibit cranial morphology that is intermediate of H. nubicolens and H. desmarestianus, suggesting the possibility of hybridization between these two species along their narrow range overlap.[2] However, genetic studies are needed to confirm hybridization within the Heteromys genus.

Geographic Range

The cloud-dwelling spiny pocket mouse (H. nubicolens) is endemic to the Cordillera de Tilarán and Cordillera de Guanacaste within Costa Rica where it ranges in elevation from 750 m to 1840 m.[2] Populations of H. nubicolens have been discovered in three highland areas--Monteverde, Volcán Rincón de la Vieja-Volcán Santa María, and Cerro Cacao--but populations may exist elsewhere in areas lacking survey efforts.[2] These populations are separated by areas of intervening lowlands, which likely causes geographic isolation.[2]

Habitat

The cloud-dwelling spiny pocket mouse (H. nubicolens) inhabits the forest floor within higher elevation forests ranging from 750 m to 1840 m, depending on the specific population.[2] Species within Heteromys tend to prefer wetter forests, in contrast to their sister genus, Liomys, that show a preference for semiarid and subtropical forests.[2] H. nubicolens appears to have a moderate tolerance for anthropogenically disturbed habitats, but is not found within highly disturbed areas such as those affected by agriculture or development.[2] Further, it can be found within both primary forests and secondary forests over 20 years old.[2] However, higher capture rates within secondary forests suggests they occur more commonly in these habitats over primary forests.[2] These mice show no difference in distribution between naturally regenerated and reforested secondary forests, suggesting they fare equally well in either habitat.[8] Variation in elevation range based on locale suggests that temperature and precipitation may both play a role in the distribution of H. nubicolens.[2]

Diet

No information is known about the dietary habits of H. nubicolens. However, H. desmarestianus is mainly a graminivore, but will occasionally also eat insects, fruits, small vertebrates, and plant matter.[9][10][11][12] Further, many other species of Heteromys have also been documented eating seeds, fruits, and insects, along with fungus. This suggests that H. nubicolens is likely a generalist graminivore.

Reproduction

Breeding can occur at any time throughout the year. [2]

Conservation Status

Preliminary research suggests that H. nubicolens does not require any species conservation protection, however, more studies on its distribution and population size are required to make an informed decision based on IUCN criteria.[2][13] Further, much of the known range of H. nubicolens is contained within extensive private and governmental reserves.[2]

Due to its preference for moderate to low disturbance, closed-canopy forests, H. nubicolens is at risk of deforestation and increased urbanization.[2]

Genetic Data

Karyotyping of H. nubicolens shows that it has a diploid number of 2n = 60 and a fundamental number of FN = 86.[2]  The unique Barcode Index Number (BIN) can be found on the Biodiversity of Life Database (BOLD) under the accession number AAC7365.[14] Sequences specimens are housed at the Royal Ontario Museum in Canada.[14]

References

  1. ^ "Heteromys nubicolens Anderson, 2006". www.gbif.org. Retrieved 15 October 2023.
  2. ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad ae af ag ah ai aj ak al am an ao ap aq ar Anderson, Robert P.; Timm, Robert M. (2006). "A New Montane Species of Spiny Pocket Mouse (Rodentia: Heteromyidae: Heteromys) from Northwestern Costa Rica". American Museum Novitates. 3509 (1): 1. doi:10.1206/0003-0082(2006)3509[1:ANMSOS]2.0.CO;2. ISSN 0003-0082.
  3. ^ Anderson, Robert P; Gutiérrez, Eliécer E (2009-12-15). "Chapter 2. Taxonomy, Distribution, and Natural History of the Genus Heteromys (Rodentia: Heteromyidae) in Central and Eastern Venezuela, with the Description of a New Species from the Cordillera de la Costa". Bulletin of the American Museum of Natural History. 331: 33–93. doi:10.1206/582-2.1. ISSN 0003-0090.
  4. ^ Hafner, John C.; Hafner, Mark S. (1983). "Evolutionary Relationships of Heteromyid Rodents". Great Basin Naturalist Memoirs (7): 3–29. ISSN 0160-239X.
  5. ^ a b c Rogers, Duke S.; González, Malinda W. (2010-08-16). "Phylogenetic relationships among spiny pocket mice (Heteromys) inferred from mitochondrial and nuclear sequence data". Journal of Mammalogy. 91 (4): 914–930. doi:10.1644/09-mamm-a-287.1. ISSN 0022-2372.
  6. ^ Anderson, Robert P.; JarríN-V, Pablo (2002-08). "A New Species of Spiny Pocket Mouse (Heteromyidae: Heteromys) Endemic to Western Ecuador". American Museum Novitates. 3382: 1–26. doi:10.1206/0003-0082(2002)382<0001:ANSOSP>2.0.CO;2. ISSN 0003-0082. {{cite journal}}: Check date values in: |date= (help)
  7. ^ Anderson, Robert (1999). "Preliminary review of the systematics and biogeography of the spiny pocket mice (Heteromys) of Colombia". Revista de la Academia Colombiana de Ciencias Exactas, Físicas y Naturales. 23: 613–630 – via ResearchGate.
  8. ^ Pruett, Noelle (2017-12-01). "The effects of reforestation on mammal diversity and abundance in Monteverde, Costa Rica". Tropical Ecology and Conservation [Monteverde Institute].
  9. ^ Rogers, D. S.; Schmidly, D. J. (1982-08-26). "Systematics of Spiny Pocket Mice (Genus Heteromys) of the Desmarestianus Species Group from Mexico and Northern Central America". Journal of Mammalogy. 63 (3): 375–386. doi:10.2307/1380434. ISSN 1545-1542.
  10. ^ Witt, Elisabeth. "Heteromys desmarestianus (Desmarest's spiny pocket mouse)". Animal Diversity Web. Retrieved 2023-10-15.
  11. ^ Janzen, Daniel H. (1983). Costa Rican Natural History. University of Chicago Press. ISBN 978-0-226-39334-6.
  12. ^ Fleming, Theodore H. (1974-05). "The Population Ecology of Two Species of Costa Rican Heteromyid Rodents". Ecology. 55 (3): 493–510. doi:10.2307/1935142. {{cite journal}}: Check date values in: |date= (help)
  13. ^ Bland, L. M.; Keith, D.A.; Miller, R.M.; Murray, N.J.; Ródriguez, J.P., eds. (2017-07-13). "Guidelines for the application of IUCN Red List of Ecosystems Categories and Criteria. Version 1.1". doi:10.2305/iucn.ch.2016.rle.3.en. {{cite journal}}: Cite journal requires |journal= (help)
  14. ^ a b "BOLD Systems: Taxonomy Browser - Heteromys nubicolens {species}". v3.boldsystems.org. Retrieved 2023-10-02.


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