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''Rhynchocyon'' is a genus of elephant shrew (or sengi) in the family Macroscelididae. Members of this genus are known colloquially as the checkered elephant shrews or giant sengis. It contains the following five species: *
Golden-rumped elephant shrew The golden-rumped elephant shrew (''Rhynchocyon chrysopygus'') is a small African mammal. It is the largest species of the elephant shrew family along with its close relative the grey-faced sengi. It is classified as endangered. Taxonomy and d ...
, ''Rhynchocyon chrysopygus'' *
Checkered elephant shrew The checkered elephant shrew or checkered sengi (''Rhynchocyon cirnei'') is a species of elephant shrew in the family Macroscelididae. Description Checked elephant shrews will grow to be around long, excluding their tail, making them one of ...
, ''Rhynchocyon cirnei'' *
Black and rufous elephant shrew The black and rufous elephant shrew (''Rhynchocyon petersi''), the black and rufous sengi, or the Zanj elephant shrew is one of the 17 species of elephant shrew found only in Africa. It is native to the lowland montane and dense forests of Kenya ...
, ''Rhynchocyon petersi'' *
Stuhlmann's elephant shrew The Stuhlmann's elephant shrew (''Rhynchocyon stuhlmanni'') is a species of elephant shrew that lives in the forests and savannas of Africa. It was discovered in 1893 and declared a new species. In the 1960s, however, it was downgraded to a sub ...
, ''Rhynchocyon stuhlmanni'' *
Grey-faced sengi The grey-faced sengi (''Rhynchocyon udzungwensis'') is a species of elephant shrew that is endemic to the Udzungwa Mountains of south-central Tanzania. The discovery of the species was announced in January 2008; only 15 species of elephant shr ...
, ''Rhynchocyon udzungwensis''


Ecology

The giant sengis are endemic to Africa, and usually live in lowland montane and dense forests, often "avoiding" edges of forest patches. They eat primarily insects such as beetles, termites, ants, and
centipede Centipedes (from New Latin , "hundred", and Latin , " foot") are predatory arthropods belonging to the class Chilopoda (Ancient Greek , ''kheilos'', lip, and New Latin suffix , "foot", describing the forcipules) of the subphylum Myriapoda, an ...
s, using their proboscises to dig them from the soil and its tongue to lick them up. Their facial morphology limits their diets to tiny invertebrates, and unlike other members of Macroscelidea, do not supplement their diet with foods such as nuts or small fruits. They typically build ground level nests for shelter requiring dry leaf litter. The primary structure of a nest for ''R. udzungwensis'', for example, consists of the excavation of a cup-like indentation in the soil, layered with leaves, and the covered with looser leaves as a roof covering. They usually construct their nests at the base of trees. They also use hollowed, fallen trees or trunks to retreat in shelter. They are typically active in the day ( diurnal), spending their nights sheltered. Other Macroscelidea species are known to bask in the sun as a method of thermoregulation to save energy. Giant sengis do not bask—and it is most likely due to their adaptation to shaded canopy forest environments. Sengis live in
monogamous Monogamy ( ) is a form of Dyad (sociology), dyadic Intimate relationship, relationship in which an individual has only one Significant other, partner during their lifetime. Alternately, only one partner at any one time (Monogamy#Serial monogamy, ...
pairs, defending hectare-sized territories. Pairs spend little time together except when the female is in
estrous The estrous cycle (, originally ) is the set of recurring physiological changes that are induced by reproductive hormones in most mammalian therian females. Estrous cycles start after sexual maturity in females and are interrupted by anestrous p ...
. Mating occurs quickly and offspring grow quickly with minimal parental investment—none of which of is paternal. Each species exhibits distinct and varying coat patterns and colors. Species and subspecies found in denser forests exhibit darker coloration and patterns while open woodland species exhibit lighter, chequers. The darker species ''R. petersi'', ''R. chrysopygus'', and ''R. udzungwensis'' still contain vestigial chequers, but are masked by the blended dark fur between them. This makes coat patterns an unreliable indicator of species delineation. The species are described as follows: *''R. chrysopygus'' exhibits a bright yellow patch of fur on its rump with very little black coloration at all. ''R. chrysopygus'' has a unique dermal shield (a specialized thickening of skin) on its rump. *''R. petersi'' has mostly orange- rufous coloration on its feet, ears, tail, chest, and on its face. Black fur extends from its rump and thighs up to its shoulders. *''R. udzungwensis'' has black feet, ears and a tail. Its face is griseous grey with its lower rump and thighs are black. The chest is pale yellow. *''R. cirnei'' and its subspecies feature six dark-colored stripes and spots (chequers) on its back. They contain little to no black fur, are lighter in color, and differ markedly by their lack of orange-rufous coloration found on its coastal relatives ''R. petersi'', ''R. chrysopygus'', and ''R. udzungwensis''. The subspecies ''R. c. macrurus'' exhibits a
clinal variation Cline may refer to: Science * Cline (biology), a measurable gradient in a single trait in a species across its geographical range * Cline (hydrology), a fluid layer with a property that varies * Cline (mathematics) or generalised circle, a circl ...
different from coastal populations towards inland populations.Corbet, G.B., Hanks, J., 1968. A revision of the elephant-shrews, family Macroscelididae. Bull. Br. Museum (Natural Hist.) Zool. 16, 45–111. *''R. stuhlmanni'' exhibits a similar coloration and pattern as ''R. cirnei'' differing notably by its white tail.


Taxonomy, distribution, and speciation

The genus' taxonomic status has been difficult to determine due to the very close similarities between populations. Up to ten species have been recognized, but over time they have been regrouped into four species. Recently, ''R. cirnei'', the species with the most subspecies, has had ''R. c. stuhlmanni'' separated into its own species based on updated molecular data. ''R. chrysopyguus'', ''R. cirnei'', and ''R. petersi'' are allopatrically distributed; with the more recently discovered ''R. udzungwensis'' and subspecies ''R. cirnei reichardi'' exhibiting parapatric distributions. Some introgression (
hybridization Hybridization (or hybridisation) may refer to: *Hybridization (biology), the process of combining different varieties of organisms to create a hybrid *Orbital hybridization, in chemistry, the mixing of atomic orbitals into new hybrid orbitals *Nu ...
) has taken place between ''R. udzungwensis'' and ''R. cirnei reichardi'' as detected by mtDNA. Estimated of population size and density vary and can be difficult to determine. However, measurements of the species populations has been undertaken. ''R. chrysopyguus'', in protected areas, is about 150 individuals per square kilometer (about 20,000 individuals); ''R. petersi'' is between 19–80 individuals per square kilometer; ''R. udzungwensis'' has an estimated 15,000–24,000 individuals. ''R. udzungwensis'' has a tiny distribution compared to the other species but resides in a protected forest.


References


External links

Sengis.org
is an overview website concerning all the sengi species maintained by researcher Galen B Rathbun of the university of the California Academy of Sciences. It hosts images, videos, bibliographies, among other topics about the order Macroscelididae. {{Taxonbar, from=Q742434 Elephant shrews Mammal genera Taxa named by Wilhelm Peters Taxonomy articles created by Polbot