Macroscelididae is a family of animals commonly known as elephant shrews, or sengis. The family contains 19 extant species within 4 currently accepted genera. The family Macroscelididae is the only extant family in the order Macroscelidea, within the superorder Afrotheria. The genera within Macroscelididae are divided in two extant subfamilies: the subfamily Rhyncocyoninae contains the genus Rhynchocyon, collectively called "giant elephant shrews" or "giant sengis", and the subfamily *Macroscelidinae contains the genera Elephantulus, Macroscelides, and Petrodromus, collectively called “soft-furred elephant shrews" or "soft-furred sengis".
Recently, researchers have discovered new species and also suggested changes to the current taxonomic relationships between members of the family Macroscelididae. In 2008, grey-faced sengis (Rhynchocyon udzungwensis) were described in the northern montane forests in Tanzania and Karoo rock sengis (Elephantulus pilicaudus) were described in South Africa. Both were established as de novo species rather than from rearrangement of previously described taxa. In 2012, Karoo round-eared sengis (Macroscelides proboscideus) and Namib round-eared sengis (Macroscelides flavicaudatus) were recently raised to full species species status from their former classification of subspecies. Furthermore, a study in 2014 identified a third, previously undescribed species in the same genus, named Etendaka round-eared sengis (Macroscelides micus).
More recently, genetic evidence suggests that species in the genus Elephantulus represent a paraphyly, and there are currently proposals to reclassify species into new genera. Namely, there is evidence that North African sengis (Elephantulus rozeti) are more closely related to four-toed sengis (Petrodromus tetradactylus) and should be reclassified as Petrosaltator rozeti. Other research indicates that Somali sengis (Elephantulus revoili) and rufous sengis (Elephantulus rufescens) belong to a newly proposed genus, Galegeeska. (Corbet and Hanks, 1968; Dumbacher, et al., 2012; Dumbacher, et al., 2014; Rathbun, 2009; Rovero, et al., 2008; Smit, et al., 2011)
Sengis are endemic to Africa. They are absent from northwest Africa and the Sahara desert. The majority of species in the family Macroscelididae are found in South Africa, around or below the equator. However, Somali sengis (Elephantulus revoili) and rufous sengis (Elephantulus rufescens) are present in the Horn of Africa and North African sengis (Elephantulus rozeti) live in the Maghreb region in northern Africa. (Corbet and Hanks, 1968; Rathbun, 2009)
Sengis are found in a wide range of terrestrial environments. They live in arid and semi-arid grasslands and shrublands, as well as closed-canopy forests, mesic woodland scrub habitats, coral rag forests, fallow agricultural sites, and arid gravel plains. Some species are found in regions with little to no vegetation and winter temperatures that fall below 0 °C. However, most sengis live in open or closed-canopy forests and establish shelters under vegetation, in rock crevices, or in burrows. Some species excavate their own burrows, but other species use abandoned termite mounds or burrows created by rodents. Giant elephant shrews (subfamily Rhynchocyoninae) will nest in leaf litter on the forest floor, but soft-furred sengis (subfamily Macroscelininae) are not known to nest in this fashion. (Rathbun, 2009)
Species in the family Macroscelididae have a complicated taxonomic history. They were considered to be closely related to true shrews (family Soricidae), moles (family Talpidae), and hedgehogs (family Erinaceidae), within the order Afrosoricida and were once included in the family Afrosoricida. However, based on more recent molecular and genetic evidence, sengis are now classified in a separate order, Macroscelidea and are considered part of the superorder Afrotheria.
Sengis are represented by one extant family, Macroscelididae, which includes two subfamilies: giant elephant shrews (Rhynchocyoninae) and the soft-furred elephant shrews(Macroscelidinae). Giant sengis are represented by the genus Rhynchocyon which currently contains four species. Soft-furred sengis by three genera, although two new genera have recently been proposed based on genetic evidence. The three genera that are currently recognized are Macroscelides, with three species, Elehpantulus, with 11 species, and Petrodromus, with one species. However, it is proposed that the genus Elephantus is polyphyletic, and that Petrodomus and Macroscelides should be subsumed within Elephantulus to create a monophyly. New evidence suggests that the sengi subfamilies diverged around 26 million years ago, with Rhynchocyoninae in eastern and central Africa and Macroscelidinae in eastern and southern Africa. Taxonomic relationships within the family Macroscelididae continue to be revised as new species are discovered or distinguished from currently recognized species. (Douady, et al., 2003; Scalici, et al., 2018; Smit, et al., 2011)
Sengis are small-bodied mammals with soft pelage that varies from gray to reddish brown in color. Sengis have long, flexible noses, a trait which characterizes the family Macroscelididae. Sengis also have long tails and long, thin legs, with hind legs that are longer than their forelegs. They also have large eyes and ears. There is some variation in size and coloration between genera in the family Macroscelididae. Soft-furred sengis (subfamily Macroscelidinae) generally have tan or brown fur, and are smaller in size, and are smaller in size, ranging from 104 to 122 mm in combined body and head length and 122 to 166 mm in tail length. Depending on the species, soft-furred sengis weigh 45 to 208 g. In contrast, giant sengis (subfamily Rhynchocyoninae) are larger and tend to have a combination of dark red, light yellow, and black coloration. On average, species of giant sengi measure 315 mm in combined body and head length and 242 mm in tail length, and they average 540.3 g in body mass. Sexual dimorphism is not common in either subfamily, although male golden-rumped sengis have slightly longer canines and thicker skin on their rumps compared to females.
The dental formulae of species in the family Macroscelididae vary slightly, but is as follows: 1-3/3 1/1, 4/4, 2/2-3 for a total of 36 to 42. Sengis have complete zygomatic arches, quadrate molars, fenestrated palates, and some species have enlarged auditory bullae. (Corbet and Hanks, 1968; Dumbacher, et al., 2012; Montuire, 2020; Rathbun, 1979)
Sengis are monogamous, although the pair bonds they form are not as strong as those of other monogamous species. Male sengis exhibit behaviors such as scent marking and mate guarding, which likely play a role in maintaining monogamous relationships. The territories of mating pairs generally overlap, although the territories of males usually do not overlap with other male territories. Their mating behaviors of many sengi species are not well understood, although there have been more in-depth studies on the mating behaviors of round-eared sengis (Macroscelides proboscideus). Round-eared sengi males and females both show sexual behavior towards neighbors of the opposite sex. Although individuals with larger body mass do not have consistently larger territories are, they do have more energy to invest in mate-guarding behaviors. (Rathbun, 1979; Schubert, et al., 2009)
Sengis typically have litters of 1 to 2 precocial young. The breeding season and amount of parental investment varies among sengi species. For example, round-eared sengis (Macroscelides proboscideus) have a breeding season that lasts from June to January, during which they produce 2 to 3 litters of young. Female round-eared sengis gestate young for an average of 61 days and enter postpartum estrus for only 1 day. In contrast, golden-rumped sengis (Rhynchocyon chrysopygus) breed throughout the year and typically have only 1 offspring per litter and rufous sengis (Elephantulus rufescens) have gestate their young for 56 days and have 1 to 2 offspring per litter. Newborn sengis are highly precocial. They are capable of standing and running within 1 day and are fully weaned after an average of 5 days. Sengi juveniles are fully independent from their parents within 25 days and by the time young are 40 days old, parents show aggressive territorial behaviors towards their offspring. (Rathbun, 1979; Schubert, et al., 2009)
Sengis exhibit limited parental investment, especially because newborn sengis are precocial and often reach complete independence within 40 days. Males do not care for their offspring, although males of many species maintain trail systems and exhibit aggression towards intruding adult males. These behaviors indirectly benefit offspring, since juveniles use the same trail systems as their parents and likely benefit from reduced competition with neighboring sengis. Females nurse their offspring, but typically for less than 1 minute per day. Otherwise, females do not associate closely with their offspring and mostly leave them in protected areas such as rock crevices or low vegetation. Sengi adults begin to display territorial behaviors towards their offspring within 40 days, although exact timing depends on local habitat quality and resource availability. (Rathbun, 1979; Schubert, et al., 2009)
Sengis live an average of 1 to 3 years in the wild, although longevity varies between species. Captive individuals have been observed to live 7 to 11 years, also depending on species. (Gomes, et al., 2011; Weigl, 2005)
Sengis are primarily cursorial, although their method of locomotion may be better defined as saltatorial in some situations. Many species of sengi are diurnal, although some are crepuscular or partially nocturnal. Sengis are sexually monogamous, but they are primarily solitary and mating pairs maintain separate or partially overlapping territories. There are no observations of coordinated activities in any sengi species with the exception of mating behavior. Although sengis occasionally share parts of their territories with their mates, the territories of neighboring males rarely overlap, and encounters between males often leads to competition. Many sengi species maintain trail networks throughout their territories, and will clear debris from their trails using their forefeet. Some species, such as golden-rumped sengis (Rhynchocyon chrysopygus), build nests by making small depressions in the soil and filling them with fallen leaves.
Sengis spend their active time maintaining their trails, foraging for insects, or seeking mates. Sengis spend the rest of their time resting in sheltered areas or basking in the sun, and many species enter torpor in cold weather. Sengis sleep briefly and intermittently, often in a crouched position and with their eyes partially open. Some species rest in abandoned burrows, while others rest under dense vegetation or in rock crevices. Sengis exhibit frequent arousals from rest and are highly vigilant while active, using their ears, eyes, and noses to sense potential predators. They are often observed flicking their tails or drumming their feet rapidly on the ground. Sengis often exhibit foot drumming when they encounter unknown conspecifics or potential threats. (Rathbun, 1979; Rathbun and Rathbun, 2006)
Sengis perceive their environment using visual, acoustic, and chemical cues. They have large eyes and ears and particularly elongated, flexible rostrums, which give them a highly developed sense of smell. While they are active, sengis constantly sniff their environment, moving their rostrums to detect scents from prey, predators, or conspecifics. Sengis exhibit limited social communication. Some sengi species will interact briefly by touching noses and sniffing each other, but this form of communication is uncommon. Most intraspecific interaction is related to reproduction. Breeding pairs will interact to reproduce, and males will interact aggressively towards neighboring males to maintain social monogamy. Sengis also display aggressive behaviors when competing for food.
Sengis communicate indirectly with conspecifics through scent marking. Many sengi species have scent glands that they rub against the ground when foraging throughout their territory. Most species exhibit some form of territory marking, although there is interspecific variation in the methods by which they scent mark. For example, rufous sengis (Elephantulus rufescens) establish dung piles instead of chemicals from scent glands to mark their territories. (Rathbun, 1979; Rathbun and Rathbun, 2006)
Sengis are primarily insectivorous, although many also consume plant material. Sengis mostly consume small invertebrates, such as termites and ants. Some sengis also eat plant seeds and fruit, such as the drupes of Premna resinosa shrubs, when available. Sengis forage primarily along their trail systems, where they use their ears and noses to detect prey on the ground or on low plants. Their dilambdodont cheek teeth support their insectivorous lifestyle. (Montuire, 2020; Rathbun, 1979)
The most common predators of species in the family Macroscelididae are birds of prey, lizards, snakes, and larger mammals. However, specific predators of different sengi species depend on their geographic range. Many sengis have cryptic coloration, with a light brown or grey pelage that helps them blend in with exposed dirt or rocks. Sengis also have behavioral adaptations to avoid predators. If they sense nearby predators, sengis instinctively remain still to not give up their location. However, if predators continue to approach their location, sengis flee along their system of trails and find another safe location wait until there is no longer a threat of predation. Sengis use their tails to slap leaf litter, or use their feet to drum the ground. These behaviors are often associated with predatory threats, and may serve as a method of communicating alarm to conspecifics. (Rathbun, 1979)
Sengis consume small invertebrates and occasionally consume plant material. They likely help control the populations of invertebrate prey and may play a limited role as seed dispersers. They also serve as prey for reptiles, birds of prey, and larger mammals. Sengis shape their immediate environment by creating and maintaining trails throughout their territory. They use these trails to forage and escape predators, but the trails are also used by other animals. Furthermore, the piles of debris that sengis create by clearing trails serve as microhabitats for invertebrate species.
Some sengi species will use abandoned burrows or nests originally made by rodents. There are reports of commensalism between small birds and sengis. As sengis forage, small birds follow them and eat any insects that sengis uncover but do not eat, such as grasshoppers (order Orthoptera) and spiders (order Araneae). (Rathbun, 1979)
There are no known positive economic impacts of sengis on humans.
There are no known negative economic impacts of sengis on humans.
Many species in the family Macroscelididae are impacted by habitat loss and fragmentation due to anthropogenic activity, such as deforestation. The populations of some species are stable, but other species, such as round-eared sengis (Macroscelides probscideus) are considered "Threatened" by the IUCN Red List. (Cole, et al., 1994; Rathbun, 1979)
Alexandria Polich (author), Colorado State University, Galen Burrell (editor), Special Projects.
living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.
uses sound to communicate
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.
an animal that mainly eats meat
uses smells or other chemicals to communicate
having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.
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.
parental care is carried out by females
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
An animal that eats mainly insects or spiders.
Having one mate at a time.
having the capacity to move from one place to another.
This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.
the area in which the animal is naturally found, the region in which it is endemic.
scrub forests develop in areas that experience dry seasons.
reproduction that includes combining the genetic contribution of two individuals, a male and a female
uses touch to communicate
Living on the ground.
A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.
A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.
A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.
uses sight to communicate
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