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Prosciurillus weberiWeber's dwarf squirrel

By Rachel Weber

Geographic Range

Prosciurillus weberi (Weber's Sulawesi dwarf squirrel) is endemic to Sulawesi in Indonesia. The voucher specimen of P. weberi was found near Palopo and Masamba, in the lowlands around the central mountains, in the east near Teluk Bone, and along the southeastern lowlands of the central core of Sulawesi. The complete geographic distribution of P. weberi is unknown and may be larger than what is represented. This expanded range may include the eastern coast of the central core of Sulawesi, westward through to the northern part of the Tempe Depression along the margin of the mountains and northwards along the western coast. (Jentink, 1890; Musser, et al., 2019; Musser, et al., 2010)

Habitat

Prosciurillus weberi is a forest obligate similar to other endemic Sulawesi squirrels, and occur in areas of tropical evergreen rain forest, where the elevation is no higher than 100 m. Little else is known about the habitat of P. weberi but it is suspected that P. weberi occupies a similar habitat to closely related species P. topapuensis and P. alstoni that both occupy the upper canopy. (Musser, et al., 2019; Musser, et al., 2010)

  • Range elevation
    100 (high) m
    328.08 (high) ft

Physical Description

Weber's Sulawesi dwarf squirrels are distinguished by a broad black band that runs from the neck towards the root of the tail, and long black fur tufts at the tips of the ears. Hair lines the inside of the pinnae and there are no nape patches behind the ears. The underside is reddish orange and the sides, body and legs are red to black. The tail tip is a black tuft, and the body of the tail has red and black rings. Weber's Sulawesi dwarf squirrels have two molars, the first of which is well developed. Weber's Sulawesi dwarf squirrels have a head to body measurement ranges from 160 mm to 187 mm, a measurement of the tail without tuft as 142 mm and a measurement of the tail with tuft as 220 mm. (Corbet and Hill, 1992; Jentink, 1890; Musser, et al., 2010)

  • Sexual Dimorphism
  • sexes alike
  • Range length
    160 to 187 mm
    6.30 to 7.36 in

Reproduction

There is little information available about the reproductive mating systems of Weber's Sulawesi dwarf squirrels.

Little information is available about the reproductive behavior of Weber's Sulawesi dwarf squirrels.

There is little information available about parental investment in reproduction in Weber's Sulawesi dwarf squirrels. However, it is likely that females do the majority of parental care, as in other squirrel species.

  • Parental Investment
  • female parental care
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • female

Lifespan/Longevity

There is little known about the lifespan of Weber's Sulawesi dwarf squirrels.

Behavior

Specifics on the behavior are unknown. However, Weber's Sulawesi dwarf squirrels are likely to be similar to other squirrels, such as being diurnal, arboreal, and communicating largely with acoustic, visual, and chemical cues. (Musser, et al., 2010)

Home Range

There is no information on home range reported in the literature. (Musser, et al., 2010)

Communication and Perception

There is limited information about communication in Weber's Sulawesi dwarf squirrels. Other members of the Prosciurillus leucomus group communicate with alarm calls in response to similar eliciting factors such as diurnal avian predators, oncoming rain, and human sounds. Calls are made individually rather than in a chorus. (Musser, et al., 2010)

Food Habits

There is little known about the food habits of Weber's Sulawesi dwarf squirrels, but it is suspected that P. weberi has a similar diet to closely related species Prosciurillus topapuensis and Prosciurillus alstoni that eat soft fruits, seeds and insects. (Musser, et al., 2010)

  • Animal Foods
  • insects
  • Plant Foods
  • seeds, grains, and nuts
  • fruit

Predation

Known predators of endemic Sulawesi squirrels include the endemic Sulawesian civet, Macrogalidia musschenbroekii, as well as diurnal avian predators such as hawks and eagles. There is limited knowledge of anti-predator responses of Weber's Sulawesi dwarf squirrels. (Musser, et al., 2010)

Ecosystem Roles

Little is known about the ecosystem roles of Weber's Sulawesi dwarf squirrels. There are no known ectoparasites of P. weberi. (Musser, et al., 2010)

Economic Importance for Humans: Positive

There are no known positive effects of Weber's Sulawesi dwarf squirrels on humans.

Economic Importance for Humans: Negative

Squirrels in the genus Prosciurillus contribute to crop loss in cacao plantations. Little else is known about adverse affects of P. weberi on humans. (Riley and Priston, 2010)

  • Negative Impacts
  • crop pest

Conservation Status

Prosciurillus weberi is considered endangered by the IUCN Red List due to continued forest destruction for logging and land clearing to create agricultural fields along the geographic range of P. weberi in south Sulawesi.There is a strong research bias towards well-known, threatened Sulawesi species in regards to conservation and it is likely that data deficient species such as P. weberi may be at higher risk than suggested. (Broto and Mortelliti, 2018; Musser, et al., 2019)

Other Comments

Prosciurillus weberi was originally named Sciurus weberi, and it remains a synonym for the species. The estimated divergence of P. weberi was 3.79 million years ago, and there has been 2 million years of divergence between individuals indicating a significant level of genetic diversity within a limited geographical range. (Hawkins, et al., 2016; Jentink, 1890)

Contributors

Rachel Weber (author), University of Manitoba, Annemarie van der Marel (editor), University of Manitoba, Tanya Dewey (editor), University of Michigan-Ann Arbor.

Glossary

Australian

Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.

World Map

acoustic

uses sound to communicate

arboreal

Referring to an animal that lives in trees; tree-climbing.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

chemical

uses smells or other chemicals to communicate

diurnal
  1. active during the day, 2. lasting for one day.
endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

female parental care

parental care is carried out by females

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

island endemic

animals that live only on an island or set of islands.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

omnivore

an animal that mainly eats all kinds of things, including plants and animals

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

tactile

uses touch to communicate

terrestrial

Living on the ground.

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

References

Broto, B., . Mortelliti. 2018. The status of research on the mammals of Sulawesi, Indonesia. Mammal Review, 41/1: 78-93.

Corbet, G., J. Hill. 1992. The mammals of the Indomalayan region: a systematic review. London, United Kingdom: Oxford University Press.

Hawkins, M., J. Leonard, K. Helgen, M. McDonough, L. Rockwood, J. Maldonado. 2016. Evolutionary history of endemic Sulawesi squirrels constructed from UCEs and mitogenomes sequenced from museum specimens. BMC Evolutionary Biology, 16:80: 80. Accessed October 27, 2019 at https://doi.org/10.1186/s12862-016-0650-z.

Jentink, F. 1890. Mammalia from the Malay Archipelago. II. Rodentia, Insectivora, Chiroptera. Pp. 115-130 in M. Weber, Zoologische Ergebnisse einer reise in Niederländisch Ost- Indien.. Leiden: E.J. Brill. Accessed October 27, 2019 at https://www.biodiversitylibrary.org/item/184538.

Musser, G., T. Dando, R. Kennerley. 2019. "Prosciurillus weberi" (On-line). The IUCN Red List of Threatened Species. Accessed October 27, 2019 at https://www.iucnredlist.org/species/18365/22256206#taxonomy.

Musser, G., L. Durden, M. Holden, J. Light. 2010. Systematic Review of Endemic Sulawesi Squirrels (Rodentia, Sciuridae), with Descriptions of New Species of Associated Sucking Lice (Insecta, Anoplura), and Phylogenetic and Zoogeographic Assessments of Sciurid Lice.. Bulletin of the American Museum of Natural History, 339.1: 1-260.

Riley, E., N. Priston. 2010. Macaques in farms and folklore: exploring the human–nonhuman primate interface in Sulawesi, Indonesia. American Journal of Primatology, 72/10: 848-854.

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