Naked-tailed Voalavo
Encyclopedia
Voalavo gymnocaudus, also known as the Northern Voalavo, Naked-tailed Voalavo, or just Voalavo, is a rodent
in the family Nesomyidae
found in the highlands of northern Madagascar
. Discovered in 1994 and formally described in 1998, it is the type species
of genus Voalavo
; its closest relative is Voalavo antsahabensis of the Central Highlands
. DNA sequence
data suggests it may be more closely related to Eliurus grandidieri than to other species of the closely related genus Eliurus
. V. gymnocaudus is found at 1250 to 1950 m (4100 to 6400 ft) above sea level in montane wet and dry forest in the Marojejy and Anjanaharibe-Sud massifs. Nocturnal and solitary, it lives mainly on the ground, but can climb, and probably eats plant matter. Despite a small range, it is classified as "Least Concern
" because it lacks obvious threats and much of its range is within protected area
s.
Voalavo gymnocaudus is a small, mouse-like rodent with soft, gray fur which is only slightly darker above than below. The ears are short and rounded. The long tail appears mostly naked and lacks a distinct tuft, which is present in Eliurus. It differs from V. antsahabensis mainly in the values of some measurements. The skull is delicate, with a long, narrow rostrum (front part), narrow interorbital region
(between the eyes), and no development of ridges on the braincase. The molars
are relatively high-crowned (hypsodont
). Body mass is 17 to 25.5 g (0.60 to 0.90 oz).
of Madagascar remained almost totally unstudied until the 1990s. A 1994 survey of the Anjanaharibe-Sud Reserve
partially filled this gap and led to the discovery of two new species: Eliurus grandidieri (genus Eliurus
) and Voalavo gymnocaudus, the first known and type species
of the genus Voalavo
. Both species were formally described in 1998 by Michael Carleton and Steven Goodman
. The generic name, Voalavo, is a general Malagasy word for rodent, and the specific name, gymnocaudus, refers to the naked tail, which distinguishes V. gymnocaudus from the related tufted-tailed rats (Eliurus). In 2000, the species was also recorded from the nearby Marojejy National Park
.
Meanwhile, in 1999, Sharon Jansa and colleagues published a molecular phylogenetic study of the Nesomyinae
, the native Malagasy rodents, using the mitochondrial
gene cytochrome b
. Their results suggested that the current definitions of Eliurus and Voalavo may not be correct, because they found that V. gymnocaudus and E. grandidieri are more closely related to each other than to the remaining species of Eliurus. However, the DNA of Eliurus petteri
, a possible close relative of E. grandidieri, could not be sampled, so Jansa and colleagues recommended further evaluation of the problem. According to a 2003 report, data from nuclear
genes also support the relationship between V. gymnocaudus and E. grandidieri, but E. petteri remains genetically unstudied and the taxonomic issue has not been resolved.
A second species of Voalavo, Voalavo antsahabensis, was named in 2005 from central Madagascar. Morphological differences between the two are subtle but consistent, and the cytochrome b sequences of the two species differ by about 10%. In mammals, closely related species regularly differ by less than 5% in their cytochrome b sequences, and a divergence of more than 5% within a single species suggests the presence of cryptic species.
Voalavo gymnocaudus is a small, mouse-like rodent. It differs from the very similar V. antsahabensis mainly in some measurements, such as a greater tail length. It also resembles small species of Eliurus, but the fur is darker and there is no tail tuft. The fur is soft, short, and thick, and appears dark gray on most of the upperparts, but more brownish on the sides. On the back, the cover hairs, which form the main part of the fur, are three-colored: most of the hair is gray, followed by a narrow light buff band and a black tip. The longer guard hair
s are black. The fur of the underparts is not different in overall color, but the individual hairs are gray for about three quarters of their length and white at the tips, except for those at the chin, which are white throughout.
The mystacial vibrissae (whiskers on the upper lips) reach the tips of the ears when pressed against the head. The short, rounded ears themselves are naked on the inside, but covered with short brown hairs on the outer surface. Females have three pairs of mammae. The digits and metapodial
s are mostly covered by white hairs. Short ungual tuft
s of hairs surrounding the bases of the claws are present. There are five pads on the forefeet and six on the hindfeet. On the hindfeet, the fifth digit is nearly as long as the middle three and the first (the hallux
) is much shorter. The tail is longer than the head and body and appears naked for most of its length, but fine hairs are visible near the tip. Although the lower side is slightly lighter, there is no clear difference in coloration between the upper and lower sides. The skin of the tail is gray, and it is covered lightly by fine hairs that are dark brown over most of the length of the tail, but white near the tip.
(a plate on the side of the skull) extends back to about the front of the first upper molar
(M1). The zygomatic notch, a notch in the upper part of the zygomatic plate, is small. The zygomatic arch
es (cheekbones) are narrow, but as usual in nesomyines contain a relatively long jugal bone. The interorbital region
(between the eyes) is narrow and short and lacks accessory shelves and ridges. The braincase also lacks such ridges.
The incisive foramina
(openings in the front part of the palate
) are medium in length, and do not reach the first molars. Their back margin is angular, not rounded as in V. antsahabensis. The diastema
(the gap between the upper incisor
s and molars) is shorter than in V. antsahabensis. The bony palate is broad and lacks notable ridges and other features, except for a pair of foramina (openings) near the place where the first and second molars (M1 and M2) meet. The back border of the palate is at the level of the middle of the third molars (M3). In the bony roof of the mesopterygoid fossa, the opening behind the palate, wide sphenopalatine vacuities
(openings) are present. A thin alisphenoid strut
(a piece of bone on the lower side of the skull separating two foramina) is present in specimens from Marojejy, but not in those from Anjanaharibe-Sud. The tegmen tympani, the roof of the tympanic cavity
, is reduced.
The root of the lower incisor is visible at the back of the mandible
(lower jaw) as a slight protrusion; a true capsular process
is absent. There are 13 thoracic (chest), 7 lumbar, 4 sacral, and 38 or 39 caudal (tail) vertebrae. The humerus
(upper arm bone) lacks an entepicondylar foramen
.
. On the lower incisor, the enamel contains series of fine ridges. The toothrows are longer than in V. antsahabensis. As in Eliurus, the molars are incipiently hypsodont
(high-crowned) and the individual cusps have lost their identities, having merged into transverse laminae that are not connected longitudinally. There are three laminae on each first and second molar, two on the third lower molar, and the laminae cannot be differentiated on the third upper molar. Although the first and second molars are similar to each other in size, the third (upper and lower) molars are conspicuously smaller. There are three roots below each upper and two below each lower molar.
, Anjanaharibe-Sud and Marojejy, but may range more widely. At Anjanaharibe-Sud, the species has been found in wet mountain forest at 1950 m (6400 ft), where it occurred with the indigenous rodents Eliurus majori and Nesomys rufus as well as the introduced
black rat
(Rattus rattus), and in drier forest at about 1300 m (4270 ft), where it may live alongside other species of Eliurus and Gymnuromys roberti. The Marojejy records come from similar habitats at 1250 to 1875 m (4100 to 6150 ft) above sea level.
V. gymnocaudus probably largely lives on the ground, but is able to climb in vegetation. It likes areas with dense networks of roots, among which it moves using runways and natural tunnels. The species is nocturnal (active during the night), is solitary, probably eats fruits and seeds, and bears up to three young per litter.
A variety of parasitic arthropod
s have been recorded on V. gymnocaudus: mite
s from the families Laelapidae
and Trombiculidae
(both Marojejy and Anjanaharibe-Sud), the demodicid mite Demodex (Marojejy only), the atopomelid mite Listrophoroides (both Marojejy and Anjanaharibe-Sud), and unidentified sucking lice
(Anjanaharibe-Sud only). In 2007, a laelapid mite found on V. gymnocaudus in Anjanaharibe-Sud was described as a new species, Andreacarus voalavo
. The apicomplexa
n parasite Eimeria
has also been recorded in Anjanaharibe-Sud V. gymnocaudus.
s. The species is therefore classified as "Least Concern
" on the IUCN Red List
.
Rodent
Rodentia is an order of mammals also known as rodents, characterised by two continuously growing incisors in the upper and lower jaws which must be kept short by gnawing....
in the family Nesomyidae
Nesomyidae
Nesomyidae is a family of African rodents in the large and complex superfamily Muroidea. It includes several subfamilies, all of which are native to either continental Africa or to Madagascar...
found in the highlands of northern Madagascar
Madagascar
The Republic of Madagascar is an island country located in the Indian Ocean off the southeastern coast of Africa...
. Discovered in 1994 and formally described in 1998, it is the type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
of genus Voalavo
Voalavo
Voalavo is a genus of rodent in the subfamily Nesomyinae, found only in Madagascar. Two species are known, both of which occur in mountain forest above 1250 m altitude; Voalavo gymnocaudus lives in northern Madagascar and Voalavo antsahabensis is restricted to a small area in the central part...
; its closest relative is Voalavo antsahabensis of the Central Highlands
Central Highlands (Madagascar)
The Central Highlands, Central High Plateau, or Hauts-Plateaux are a mountainous biogeographical region in central Madagascar. They include the contiguous part of the island's interior above 800 m altitude...
. DNA sequence
DNA sequence
The sequence or primary structure of a nucleic acid is the composition of atoms that make up the nucleic acid and the chemical bonds that bond those atoms. Because nucleic acids, such as DNA and RNA, are unbranched polymers, this specification is equivalent to specifying the sequence of...
data suggests it may be more closely related to Eliurus grandidieri than to other species of the closely related genus Eliurus
Eliurus
Eliurus is a genus of rodent in the family Nesomyidae.It contains the following species:* Tsingy Tufted-tailed Rat * Ankarana Special Reserve Tufted-tailed Rat...
. V. gymnocaudus is found at 1250 to 1950 m (4100 to 6400 ft) above sea level in montane wet and dry forest in the Marojejy and Anjanaharibe-Sud massifs. Nocturnal and solitary, it lives mainly on the ground, but can climb, and probably eats plant matter. Despite a small range, it is classified as "Least Concern
Least Concern
Least Concern is an IUCN category assigned to extant taxon or lower taxa which have been evaluated but do not qualify for any other category. As such they do not qualify as threatened, Near Threatened, or Conservation Dependent...
" because it lacks obvious threats and much of its range is within protected area
Protected area
Protected areas are locations which receive protection because of their recognised natural, ecological and/or cultural values. There are several kinds of protected areas, which vary by level of protection depending on the enabling laws of each country or the regulations of the international...
s.
Voalavo gymnocaudus is a small, mouse-like rodent with soft, gray fur which is only slightly darker above than below. The ears are short and rounded. The long tail appears mostly naked and lacks a distinct tuft, which is present in Eliurus. It differs from V. antsahabensis mainly in the values of some measurements. The skull is delicate, with a long, narrow rostrum (front part), narrow interorbital region
Interorbital region
The interorbital region of the skull is located between the eyes, anterior to the braincase. The form of the interorbital region may exhibit significant variation between taxonomic groups....
(between the eyes), and no development of ridges on the braincase. The molars
Molar (tooth)
Molars are the rearmost and most complicated kind of tooth in most mammals. In many mammals they grind food; hence the Latin name mola, "millstone"....
are relatively high-crowned (hypsodont
Hypsodont
Hypsodont dentition is characterized by high-crowned teeth and enamel which extends past the gum line. This provides extra material for wear and tear. Some examples of animals with hypsodont dentition are cows, horses and deer; all animals that feed on gritty, fibrous material. The opposite...
). Body mass is 17 to 25.5 g (0.60 to 0.90 oz).
Taxonomy
The rodent fauna of the Northern HighlandsNorthern Highlands
The Northern Highlands are a mountainous biogeographical region of northern Madagascar. The region includes the Tsaratanana Massif and smaller nearby massifs such as Marojejy, Anjanaharibe-Sud, and Manongarivo...
of Madagascar remained almost totally unstudied until the 1990s. A 1994 survey of the Anjanaharibe-Sud Reserve
Anjanaharibe-Sud Reserve
Anjanaharibe-Sud Reserve is a wildlife reserve of Madagascar. It was nominated to the UNESCO Tentative List of World Heritage Sites in Madagascar in 2008 as an extension to the Rainforests of the Atsinanana....
partially filled this gap and led to the discovery of two new species: Eliurus grandidieri (genus Eliurus
Eliurus
Eliurus is a genus of rodent in the family Nesomyidae.It contains the following species:* Tsingy Tufted-tailed Rat * Ankarana Special Reserve Tufted-tailed Rat...
) and Voalavo gymnocaudus, the first known and type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
of the genus Voalavo
Voalavo
Voalavo is a genus of rodent in the subfamily Nesomyinae, found only in Madagascar. Two species are known, both of which occur in mountain forest above 1250 m altitude; Voalavo gymnocaudus lives in northern Madagascar and Voalavo antsahabensis is restricted to a small area in the central part...
. Both species were formally described in 1998 by Michael Carleton and Steven Goodman
Steven Goodman
Steven Goodman is an American Conservation Biologist, and field biologist on staff in the Department of Zoology at the Field Museum of Natural History....
. The generic name, Voalavo, is a general Malagasy word for rodent, and the specific name, gymnocaudus, refers to the naked tail, which distinguishes V. gymnocaudus from the related tufted-tailed rats (Eliurus). In 2000, the species was also recorded from the nearby Marojejy National Park
Marojejy National Park
Marojejy National Park is a national park in the Sava Region of northeastern Madagascar. It covers and is centered around the Marojejy Massif, a mountain chain that rises to an elevation of . Access to the area around the massif was restricted to research scientists when the site was set aside as...
.
Meanwhile, in 1999, Sharon Jansa and colleagues published a molecular phylogenetic study of the Nesomyinae
Nesomyinae
The Malagasy rats and mice are the sole members of the subfamily Nesomyinae. These animals are the only native rodents of Madagascar, come in many shapes and sizes, and occupy a wide variety of ecological niches. There are nesomyines that resemble gerbils, rats, mice, voles, and even rabbits...
, the native Malagasy rodents, using the mitochondrial
Mitochondrial DNA
Mitochondrial DNA is the DNA located in organelles called mitochondria, structures within eukaryotic cells that convert the chemical energy from food into a form that cells can use, adenosine triphosphate...
gene cytochrome b
Cytochrome b
Cytochrome b/b6 is the main subunit of transmembrane cytochrome bc1 and b6f complexes. In addition, it commonly refers to a region of mtDNA used for population genetics and phylogenetics.- Function :...
. Their results suggested that the current definitions of Eliurus and Voalavo may not be correct, because they found that V. gymnocaudus and E. grandidieri are more closely related to each other than to the remaining species of Eliurus. However, the DNA of Eliurus petteri
Eliurus petteri
Eliurus petteri is a rodent in the genus Eliurus found in lowland eastern Madagascar. First described in 1994, it is most closely related to the smaller Eliurus grandidieri. Virtually nothing is known of its natural history, except that it occurs in rainforest and is nocturnal and solitary...
, a possible close relative of E. grandidieri, could not be sampled, so Jansa and colleagues recommended further evaluation of the problem. According to a 2003 report, data from nuclear
Nuclear DNA
Nuclear DNA, nuclear deoxyribonucleic acid , is DNA contained within a nucleus of eukaryotic organisms. In mammals and vertebrates, nuclear DNA encodes more of the genome than the mitochondrial DNA and is composed of information inherited from two parents, one male, and one female, rather than...
genes also support the relationship between V. gymnocaudus and E. grandidieri, but E. petteri remains genetically unstudied and the taxonomic issue has not been resolved.
A second species of Voalavo, Voalavo antsahabensis, was named in 2005 from central Madagascar. Morphological differences between the two are subtle but consistent, and the cytochrome b sequences of the two species differ by about 10%. In mammals, closely related species regularly differ by less than 5% in their cytochrome b sequences, and a divergence of more than 5% within a single species suggests the presence of cryptic species.
External morphology
| Locality | n | Head-body | Tail | Hindfoot | Ear | Mass |
|---|---|---|---|---|---|---|
| Anjanaharibe-Sud | 4 | 86–90 | 119–120 | 20–21 | – | 20.5–23.5 |
| Marojejy | 5 | 80–90 | 113–126 | 17–20 | 15–15 | 17.0–25.5 |
| n: Number of specimens measured. All measurements are in millimeters, except body mass in grams. |
||||||
Voalavo gymnocaudus is a small, mouse-like rodent. It differs from the very similar V. antsahabensis mainly in some measurements, such as a greater tail length. It also resembles small species of Eliurus, but the fur is darker and there is no tail tuft. The fur is soft, short, and thick, and appears dark gray on most of the upperparts, but more brownish on the sides. On the back, the cover hairs, which form the main part of the fur, are three-colored: most of the hair is gray, followed by a narrow light buff band and a black tip. The longer guard hair
Guard hair
Guard hairs are the longest, coarsest hairs in a mammal's coat, forming the topcoat . They taper to a point and protect the undercoat from the elements. They are often water repellent and stick out above the rest of the coat...
s are black. The fur of the underparts is not different in overall color, but the individual hairs are gray for about three quarters of their length and white at the tips, except for those at the chin, which are white throughout.
The mystacial vibrissae (whiskers on the upper lips) reach the tips of the ears when pressed against the head. The short, rounded ears themselves are naked on the inside, but covered with short brown hairs on the outer surface. Females have three pairs of mammae. The digits and metapodial
Metapodial
Metapodials are long bones of the hand and feet which connect the digits to the centers. In humans, five are present in each hand and foot....
s are mostly covered by white hairs. Short ungual tuft
Ungual tuft
In mammals, ungual tufts are tufts of hairs at the base of claws of the fore- and hindfeet. Their presence has been used as a character in cladistic studies of Cricetidae....
s of hairs surrounding the bases of the claws are present. There are five pads on the forefeet and six on the hindfeet. On the hindfeet, the fifth digit is nearly as long as the middle three and the first (the hallux
Hallux
In tetrapods, the hallux is the innermost toe of the foot. Despite its name it may not be the longest toe on the foot of some individuals...
) is much shorter. The tail is longer than the head and body and appears naked for most of its length, but fine hairs are visible near the tip. Although the lower side is slightly lighter, there is no clear difference in coloration between the upper and lower sides. The skin of the tail is gray, and it is covered lightly by fine hairs that are dark brown over most of the length of the tail, but white near the tip.
Skeleton
The skull is delicate and lightly built. The rostrum, the front part of the skull, is narrow and fairly long; it is shorter in V. antsahabensis. The narrow zygomatic plateZygomatic plate
In rodent anatomy, the zygomatic plate is a bony plate derived from the flattened front part of the zygomatic arch . At the back, it connects to the front root of the zygomatic arch, and at the top it is connected to the rest of the skull via the antorbital bridge. It is part of the maxillary...
(a plate on the side of the skull) extends back to about the front of the first upper molar
Molar (tooth)
Molars are the rearmost and most complicated kind of tooth in most mammals. In many mammals they grind food; hence the Latin name mola, "millstone"....
(M1). The zygomatic notch, a notch in the upper part of the zygomatic plate, is small. The zygomatic arch
Zygomatic arch
The zygomatic arch or cheek bone is formed by the zygomatic process of temporal bone and the temporal process of the zygomatic bone , the two being united by an oblique suture; the tendon of the Temporalis passes medial to the arch to gain insertion into the coronoid process...
es (cheekbones) are narrow, but as usual in nesomyines contain a relatively long jugal bone. The interorbital region
Interorbital region
The interorbital region of the skull is located between the eyes, anterior to the braincase. The form of the interorbital region may exhibit significant variation between taxonomic groups....
(between the eyes) is narrow and short and lacks accessory shelves and ridges. The braincase also lacks such ridges.
The incisive foramina
Incisive foramen
The fossa incisiva is an opening in the bone of the oral hard palate where blood vessels and nerves may pass. There are four of these openings in the incisive fossa.-Formation:...
(openings in the front part of the palate
Palate
The palate is the roof of the mouth in humans and other mammals. It separates the oral cavity from the nasal cavity. A similar structure is found in crocodilians, but, in most other tetrapods, the oral and nasal cavities are not truly separate. The palate is divided into two parts, the anterior...
) are medium in length, and do not reach the first molars. Their back margin is angular, not rounded as in V. antsahabensis. The diastema
Diastema (dentistry)
Diastema is a space or gap between two teeth. Many species of mammals have diastemata as a normal feature, most commonly between the incisors and molars.-In humans:...
(the gap between the upper incisor
Incisor
Incisors are the first kind of tooth in heterodont mammals. They are located in the premaxilla above and mandible below.-Function:...
s and molars) is shorter than in V. antsahabensis. The bony palate is broad and lacks notable ridges and other features, except for a pair of foramina (openings) near the place where the first and second molars (M1 and M2) meet. The back border of the palate is at the level of the middle of the third molars (M3). In the bony roof of the mesopterygoid fossa, the opening behind the palate, wide sphenopalatine vacuities
Sphenopalatine vacuities
In rodents, sphenopalatine vacuities are perforations of the roof of the mesopterygoid fossa, the open space behind the palate, in between the parapterygoid fossae. They may perforate the presphenoid or basisphenoid bone...
(openings) are present. A thin alisphenoid strut
Alisphenoid strut
In some rodents, the alisphenoid strut is an extension of the alisphenoid bone that separates two foramina in the skull, the masticatory–buccinator foramen and the foramen ovale accessorius...
(a piece of bone on the lower side of the skull separating two foramina) is present in specimens from Marojejy, but not in those from Anjanaharibe-Sud. The tegmen tympani, the roof of the tympanic cavity
Tympanic cavity
The tympanic cavity is a small cavity surrounding the bones of the middle ear.It is formed from the tubotympanic recess, an expansion of the first pharyngeal pouch....
, is reduced.
The root of the lower incisor is visible at the back of the mandible
Mandible
The mandible pronunciation or inferior maxillary bone forms the lower jaw and holds the lower teeth in place...
(lower jaw) as a slight protrusion; a true capsular process
Capsular process
In rodents, the capsular process or projection is a bony capsule that contains the root of the lower incisor. It is visible on the labial side of the mandible as a raising in the bone...
is absent. There are 13 thoracic (chest), 7 lumbar, 4 sacral, and 38 or 39 caudal (tail) vertebrae. The humerus
Humerus
The humerus is a long bone in the arm or forelimb that runs from the shoulder to the elbow....
(upper arm bone) lacks an entepicondylar foramen
Entepicondylar foramen
The entepicondylar foramen is an opening in the distal end of the humerus present in some mammals. It is often present in primitive placentals, such as the enigmatic Madagascan Plesiorycteropus...
.
Dentition
The upper incisors are orthodont (with their cutting edge perpendicular to the plane formed by the molars) and have yellow to light orange enamelTooth enamel
Tooth enamel, along with dentin, cementum, and dental pulp is one of the four major tissues that make up the tooth in vertebrates. It is the hardest and most highly mineralized substance in the human body. Tooth enamel is also found in the dermal denticles of sharks...
. On the lower incisor, the enamel contains series of fine ridges. The toothrows are longer than in V. antsahabensis. As in Eliurus, the molars are incipiently hypsodont
Hypsodont
Hypsodont dentition is characterized by high-crowned teeth and enamel which extends past the gum line. This provides extra material for wear and tear. Some examples of animals with hypsodont dentition are cows, horses and deer; all animals that feed on gritty, fibrous material. The opposite...
(high-crowned) and the individual cusps have lost their identities, having merged into transverse laminae that are not connected longitudinally. There are three laminae on each first and second molar, two on the third lower molar, and the laminae cannot be differentiated on the third upper molar. Although the first and second molars are similar to each other in size, the third (upper and lower) molars are conspicuously smaller. There are three roots below each upper and two below each lower molar.
Distribution and ecology
Voalavo gymnocaudus has been found only in two massifs of the Northern HighlandsNorthern Highlands
The Northern Highlands are a mountainous biogeographical region of northern Madagascar. The region includes the Tsaratanana Massif and smaller nearby massifs such as Marojejy, Anjanaharibe-Sud, and Manongarivo...
, Anjanaharibe-Sud and Marojejy, but may range more widely. At Anjanaharibe-Sud, the species has been found in wet mountain forest at 1950 m (6400 ft), where it occurred with the indigenous rodents Eliurus majori and Nesomys rufus as well as the introduced
Introduced species
An introduced species — or neozoon, alien, exotic, non-indigenous, or non-native species, or simply an introduction, is a species living outside its indigenous or native distributional range, and has arrived in an ecosystem or plant community by human activity, either deliberate or accidental...
black rat
Black Rat
The black rat is a common long-tailed rodent of the genus Rattus in the subfamily Murinae . The species originated in tropical Asia and spread through the Near East in Roman times before reaching Europe by the 1st century and spreading with Europeans across the world.-Taxonomy:The black rat was...
(Rattus rattus), and in drier forest at about 1300 m (4270 ft), where it may live alongside other species of Eliurus and Gymnuromys roberti. The Marojejy records come from similar habitats at 1250 to 1875 m (4100 to 6150 ft) above sea level.
V. gymnocaudus probably largely lives on the ground, but is able to climb in vegetation. It likes areas with dense networks of roots, among which it moves using runways and natural tunnels. The species is nocturnal (active during the night), is solitary, probably eats fruits and seeds, and bears up to three young per litter.
A variety of parasitic arthropod
Arthropod
An arthropod is an invertebrate animal having an exoskeleton , a segmented body, and jointed appendages. Arthropods are members of the phylum Arthropoda , and include the insects, arachnids, crustaceans, and others...
s have been recorded on V. gymnocaudus: mite
Mite
Mites, along with ticks, are small arthropods belonging to the subclass Acari and the class Arachnida. The scientific discipline devoted to the study of ticks and mites is called acarology.-Diversity and systematics:...
s from the families Laelapidae
Laelapidae
Laelapidae is a family of mites in the order Mesostigmata.-Genera:* Aetholaelaps Strandtmann & Camin, 1956* Alphalaelaps Radford, 1951* Andreacarus Radford, 1953* Androlaelaps Berlese, 1903* Angosomaspis Costa, 1971...
and Trombiculidae
Trombiculidae
Trombiculidae is a family of mites called trombiculid mites Trombiculidae is a family of mites called trombiculid mites Trombiculidae is a family of mites called trombiculid mites (also called berry bugs; harvest mites; red bugs; scrub-itch mites; and aoutas. In their larval stage, those...
(both Marojejy and Anjanaharibe-Sud), the demodicid mite Demodex (Marojejy only), the atopomelid mite Listrophoroides (both Marojejy and Anjanaharibe-Sud), and unidentified sucking lice
Sucking louse
Sucking lice have around 500 species and represent the smaller of the two traditional suborders of lice. As opposed to the paraphyletic chewing lice, which are now divided among three suborders, the sucking lice are monophyletic.The Anoplura are all blood-feeding ectoparasites of mammals...
(Anjanaharibe-Sud only). In 2007, a laelapid mite found on V. gymnocaudus in Anjanaharibe-Sud was described as a new species, Andreacarus voalavo
Andreacarus voalavo
Andreacarus voalavo is a parasitic mite found on the Malagasy rodent Voalavo gymnocaudus. First described in 2007, it is closely related to Andreacarus gymnuromys and Andreacarus eliurus, which are found on other Malagasy rodents. The length of the idiosoma, the main body, is 630 to 670 μm in...
. The apicomplexa
Apicomplexa
The Apicomplexa are a large group of protists, most of which possess a unique organelle called apicoplast and an apical complex structure involved in penetrating a host's cell. They are unicellular, spore-forming, and exclusively parasites of animals. Motile structures such as flagella or...
n parasite Eimeria
Eimeria
Eimeria is a genus of Apicomplexan parasites that includes various species responsible for the poultry disease coccidiosis. The genus is named for the German zoologist Theodor Eimer...
has also been recorded in Anjanaharibe-Sud V. gymnocaudus.
Conservation status
Although Voalavo gymnocaudus has a small range and is uncommon even within that range, no major threats are known and virtually all of its distribution is within protected areaProtected area
Protected areas are locations which receive protection because of their recognised natural, ecological and/or cultural values. There are several kinds of protected areas, which vary by level of protection depending on the enabling laws of each country or the regulations of the international...
s. The species is therefore classified as "Least Concern
Least Concern
Least Concern is an IUCN category assigned to extant taxon or lower taxa which have been evaluated but do not qualify for any other category. As such they do not qualify as threatened, Near Threatened, or Conservation Dependent...
" on the IUCN Red List
IUCN Red List
The IUCN Red List of Threatened Species , founded in 1963, is the world's most comprehensive inventory of the global conservation status of biological species. The International Union for Conservation of Nature is the world's main authority on the conservation status of species...
.