Eastern voalavo

Last updated

Eastern voalavo
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Rodentia
Family: Nesomyidae
Genus: Voalavo
Species:
V. antsahabensis
Binomial name
Voalavo antsahabensis
Goodman et al., 2005
Voalavo range.svg
Known records of Voalavo antsahabensis (green) and Voalavo gymnocaudus (red)

The eastern voalavo (Voalavo antsahabensis) is a rodent in the family Nesomyidae which occurs in the Anjozorobe forest of eastern Madagascar. Although surveys before 2002 failed to record the species, it is common in some places. However, it is threatened by habitat loss because of slash-and-burn agriculture. The species was formally described in 2005 and is most closely related to the only other species of Voalavo , the northern voalavo from northern Madagascar.

Contents

The two species of Voalavo are only subtly different in morphology. With a body mass of 20.7 to 22.6 g (0.73 to 0.80 oz), the eastern voalavo is a small rodent. It has a longer tail than the northern voalavo, as well as a longer rostrum (front part of the skull) and diastema (gap between the incisors and molars), but shorter molar rows. The two species also differ in details of the configuration of the palate.

Taxonomy

It was first recorded in 2002, [1] when three individuals were captured in Madagascar's Anjozorobe forest. In 2005, the species was formally described by Steven Goodman and colleagues as Voalavo antsahabensis, the second species in the genus Voalavo . The only previously known species, the northern voalavo, occurs further to the north, in the Northern Highlands. [2] The sequences of the cytochrome b gene differ by about 10% in these two species. [3] The specific name, antsahabensis, derives from the name of the village of Antsahabe, which is near the place where the holotype was found. [4] The common name "Eastern Voalavo" has been used for this species. [1]

Description

Species of Voalavo are small rodents with a delicate skull and without a tuft at the tip of the tail (as present in the closely related genus Eliurus ). [5] The eastern voalavo is similar to the northern voalavo and differs only in subtle characters. [4] The tail is shorter in the eastern voalavo, but the head and body is slightly longer, as is the ear. However, the latter two apparent contrasts may be the result of differences in measurement technique. [6] In both species, the final 25 to 30 mm (0.98 to 1.18 in) of the tail are covered with white hairs. [7] In three specimens of eastern voalavo, head and body length ranges from 88 to 91 mm (3.5 to 3.6 in), tail length is 106 to 114 mm (4.2 to 4.5 in), hindfoot length 19 to 20 mm (0.75 to 0.79 in), ear length 15 to 16 mm (0.59 to 0.63 in), and body mass 20.7 to 22.6 g (0.73 to 0.80 oz). [8]

In the skull, it has a significantly longer rostrum (the front part of the skull) and diastema (the gap between the incisors and the molars). [7] Furthermore, it has shorter molar rows in both the upper and lower jaws. [8] The back end of the incisive foramina (openings in the front part of the palate), which is located in front of the first molars, is rounded in eastern voalavo, but angular in northern voalavo. [9] The sutures of the maxillary and palatine bones (the line where the two bones, part of the skull, join) are straight and parallel to each other, the toothrows, and the midline of the skull in eastern voalavo. Northern voalavo, in contrast, are more curved. Statistical analysis of measurements of the skull and teeth clearly separates the two species of Voalavo. [4]

Distribution and ecology

It is only known from the forests at Anjozorobe, on the eastern margin of Madagascar's Central Highlands. Among the specimens found in 2002, two were captured at 1,425 m (4,675 ft) altitude on a Uapaca densifolia branch, about 1.5 m (4.9 ft) over the ground, in moist montane forest, and a third was caught on the ground at 1,275 m (4,183 ft) altitude. [10] This last specimen, a male, had its testicles located in the scrotum, and therefore was reproductively mature, even though its skull bones were not completely fused, indicating it was not yet osteologically mature. [4] Before it was collected in 2002, the species was not recorded in earlier biological surveys of Anjozorobe, taking place in 1977–1986 and 1996; whether this is because the animal is difficult to collect, because its abundance varies from year to year, or because its distribution is patchy is unknown. Goodman and colleagues argued on the basis of this example that rapid surveys may not necessarily yield complete inventories of the fauna of an area. [3] Later surveys in 2005 and 2006 did find it at several other sites in the region, at some of which it was abundant. [1] Anjozorobe is about 450 km (280 mi) from the nearest occurrence of northern voalavo, and most of the intervening area contains montane forest. However, this forest zone is bisected by the low-lying Mandritsara Window, which may serve as a barrier between the two species of Voalavo. [11]

Conservation status

It is listed as "Endangered" on the IUCN Red List because of its small, vulnerable range; the Anjozorobe forest is threatened by the practice of slash-and-burn agriculture (tavy). However, its habitat has been designated as a protected area, the Couloir Forestier d'Anjozorobe-Angavo. [1]

Related Research Articles

<i>Oryzomys gorgasi</i> Rodent from the family Cricetidae from northwestern Colombia and Venezuela

Oryzomys gorgasi, also known as Gorgas's oryzomys or Gorgas's rice rat, is a rodent in the genus Oryzomys of family Cricetidae. First recorded in 1967, it is known from only a few localities, including a freshwater swamp in the lowlands of northwestern Colombia and a mangrove islet in northwestern Venezuela. It reportedly formerly occurred on the island of Curaçao off northwestern Venezuela; this extinct population has been described as a separate species, Oryzomys curasoae, but does not differ morphologically from mainland populations.

<span class="mw-page-title-main">Hammond's rice rat</span> Species of rodent in the family Cricetidae from Ecuador

Mindomys hammondi, also known as Hammond's rice rat or Hammond's oryzomys, is an endangered species of rodent in the tribe Oryzomyini of family Cricetidae. Formerly considered to be related with Nectomys, Sigmodontomys, Megalomys, or Oryzomys, it is now placed in then genus Mindomys, but its relationships remain obscure; some evidence supports a placement near Oecomys or as a basal member of Oryzomyini.

Nephelomys levipes, also known as the nimble-footed oryzomys or light-footed rice rat, is a species of rodent in the genus Nephelomys of family Cricetidae. It is found on the eastern slope of the Andes from southeastern Peru into west-central Bolivia in cloud forest at elevations from 1,800 to 3,200 metres. It occurs in the same general area as its congener N. keaysi, but at higher altitudes.

<i>Eremoryzomys</i> Rodent species in the family Cricetidae from central Peru

Eremoryzomys polius, also known as the gray rice rat or the Marañon oryzomys, is a rodent species in the tribe Oryzomyini of the family Cricetidae. Discovered in 1912 and first described in 1913 by Wilfred Osgood, it was originally placed in Oryzomys and named Oryzomys polius. In 2006, a cladistic analysis found that it was not closely related to Oryzomys in the strict sense or to any other oryzomyine then known, so that it is now placed in its own genus, Eremoryzomys. The Brazilian genus Drymoreomys, named in 2011, is probably the closest relative of Eremoryzomys. Eremoryzomys has a limited distribution in the dry upper valley of the Marañón River in central Peru, but may yet contain more than one species.

<i>Transandinomys talamancae</i> Small rodent found from Costa Rica to northern South America

Transandinomys talamancae is a rodent in the family Cricetidae that occurs from Costa Rica to southwestern Ecuador and northern Venezuela. Its habitat consists of lowland forests up to 1,500 m (5,000 ft) above sea level. With a body mass of 38 to 74 g, it is a medium-sized rice rat. The fur is soft and is reddish to brownish on the upperparts and white to buff on the underparts. The tail is dark brown above and lighter below and the ears and feet are long. The vibrissae (whiskers) are very long. In the skull, the rostrum is long and the braincase is low. The number of chromosomes varies from 34 to 54.

<i>Thomasomys ucucha</i> Species of rodent from Ecuador

Thomasomys ucucha, also known as the ucucha thomasomys, is a rodent in the genus Thomasomys of the family Cricetidae. It is known only from high altitude forest and grassland habitats in the Cordillera Oriental of Ecuador. Seven other species of Thomasomys live in the same areas. First collected in 1903, T. ucucha was formally described as a new species in 2003 and most closely resembles T. hylophilus, which occurs further to the north. The species is listed as "vulnerable" in the IUCN Red List as a result of habitat destruction.

<i>Juliomys anoblepas</i> Species of rodent

Juliomys anoblepas is a rodent in the genus Juliomys of the subfamily Sigmodontinae known from a single broken skull. The specimen was collected by Peter Wilhelm Lund in the caves of Lagoa Santa, Minas Gerais, Brazil, in the first half of the 19th century and described by Herluf Winge in 1888 as Calomys anoblepas. The species remained unstudied and its affinities unclear until 2011, when it was recognized as a member of the genus Juliomys, which includes three other species from southern Brazil and nearby Argentina and Paraguay. J. anoblepas is probably a separate extinct species of the genus, which is no longer found at Lagoa Santa.

Calomys cerqueirai is a species of rodent in the genus Calomys from southeastern Brazil. Distinct from other Calomys in its karyotype and characters of the fur, it is known only from two places in Minas Gerais. The karyotype was first described in 1996 and the species was formally named in 2010.

<i>Voalavo</i> Genus of rodents from Madagascar

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 (4100 ft) altitude; the northern voalavo lives in northern Madagascar and eastern voalavo is restricted to a small area in the central part of the island. The genus was discovered in 1994 and formally described in 1998. Within Nesomyinae, it is most closely related to the genus Eliurus, and DNA sequence data suggest that the current definitions of these two genera need to be changed.

<span class="mw-page-title-main">Northern voalavo</span> Rodent in the family Nesomyidae

The northern voalavo, also known as the naked-tailed voalavo or simply the voalavo, is a rodent in the family Nesomyidae found in the Northern Highlands of Madagascar. Discovered in 1994 and formally described in 1998, it is the type species of the genus Voalavo; its closest relative is the eastern voalavo of the Central Highlands. DNA sequencing suggests that it may be more closely related to Grandidier's tufted-tailed rat than to other species of the closely related genus Eliurus. The northern voalavo is found at 1,250 to 1,950 m above sea level in montane wet and dry forests in the Marojejy and Anjanaharibe-Sud massifs. Nocturnal and solitary, it lives mainly on the ground, but it can climb and probably eats plant matter. Despite having a small range, the species is classified as being of least concern because it lacks obvious threats and much of its range is within protected areas.

<i>Microgale macpheei</i> An extinct shrew tenrec from southeastern Madagascar

Microgale macpheei is an extinct shrew tenrec from southeastern Madagascar. It is known only from two partial skulls found in Andrahomana cave, which radiocarbon dating of associated rodent remains suggests are about 3000 years old. It is the only known recently extinct tenrec. First described in 2007, it is most similar to the smaller Microgale brevicaudata of northern and western Madagascar. M. macpheei has a broad rostrum and, like M. brevicaudata, lacks a diastema (gap) between the premolars. A number of details of tooth morphology are characteristic of M. macpheei.

<i>Triaenops menamena</i> Bat species found in Madagascar

Triaenops menamena is a bat in the genus Triaenops found on Madagascar, mainly in the drier regions. It was known as Triaenops rufus until 2009, when it was discovered that that name had been incorrectly applied to the species. Triaenops rufus is a synonym of Triaenops persicus, a Middle Eastern species closely related to T. menamena— the Malagasy species had previously been placed as a subspecies of T. persicus by some authors. Triaenops menamena is mostly found in forests, but also occurs in other habitats. It often roosts in large colonies and eats insects such as butterflies and moths. Because of its wide range, common occurrence, and tolerance of habitat degradation, it is not considered to be threatened.

<i>Pipistrellus raceyi</i> Species of bat from Madagascar

Pipistrellus raceyi, also known as Racey's pipistrelle, is a bat from Madagascar, in the genus Pipistrellus. Although unidentified species of Pipistrellus had been previously reported from Madagascar since the 1990s, P. raceyi was not formally named until 2006. It is apparently most closely related to the Asian species P. endoi, P. paterculus, and P. abramus, and its ancestors probably reached Madagascar from Asia. P. raceyi has been recorded at four sites, two in the eastern and two in the western lowlands. In the east, it is found in open areas and has been found roosting in a building; in the west it occurs in dry forest. Because of uncertainties about its ecology, it is listed as "Data Deficient" on the IUCN Red List.

<span class="mw-page-title-main">Central Highlands (Madagascar)</span> Biogeographical region in Central 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 (2,600 ft) elevation. The Central Highlands are separated from the Northern Highlands of the northern tip of Madagascar by a low-lying valley, the Mandritsara Window, which has apparently acted as a barrier to dispersal for species in the highlands, leading to species pairs such as Voalavo gymnocaudus and Voalavo antsahabensis in the Northern and Central Highlands. Species restricted to the Central Highlands include the bats Miniopterus manavi and Miniopterus sororculus; the rodents Brachyuromys betsileoensis and Voalavo antsahabensis; the tenrecs Hemicentetes nigriceps and Oryzorictes tetradactylus; and the lemur Cheirogaleus sibreei. Because of the continuous habitat of the Central Highlands, there is little local endemism, unlike the Northern Highlands.

<i>Miniopterus brachytragos</i> Species of mammal bat in the genus Miniopterus that occurs in northern and western Madagascar

Miniopterus brachytragos is a bat in the genus Miniopterus that occurs in northern and western Madagascar. Populations of this species have historically been included in Miniopterus manavi, but molecular data published in 2008 and 2009 indicate this supposed species in fact consists of five separate species, including the newly described M. brachytragos. Up to four species of this group may occur in the same place. M. brachytragos has been found in dry and wet forests from sea level to 320 m (1,050 ft) altitude.

<i>Miniopterus mahafaliensis</i> A bat in the genus Miniopterus that occurs in southwestern Madagascar

Miniopterus mahafaliensis is a bat in the genus Miniopterus that occurs in southwestern Madagascar. Populations of this species have historically been included in Miniopterus manavi, but molecular data published in 2008 and 2009 indicate that this supposed species in fact consists of five separate species, including the newly described M. mahafaliensis. The species has been found in dry, spiny, and gallery forest, as well as more open habitats, in southwestern Madagascar.

<span class="mw-page-title-main">Durrell's vontsira</span> Small species of carnivoran from Madagascar

Durrell's vontsira is a small, reddish-brown, fox-like mammal native to the island of Madagascar. Discovered in 2004, it lives only in the biodiverse wetlands of Lake Alaotra. Durrell's vontsira belongs to the family Eupleridae, a group of meat-eating, cat- or fox-like mammals found only on Madagascar. The species is closely related to the brown-tailed mongoose, with which it forms the genus Salanoia. The two are genetically similar, but morphologically distinct, and S. durrelli was described as a new species in 2010.

<span class="mw-page-title-main">Malagasy mountain mouse</span> Small rodent found in the highlands of eastern Madagascar

The Malagasy mountain mouse or Koopman's montane voalavo is a rodent within the subfamily Nesomyinae of the family Nesomyidae. It is monotypic within the genus Monticolomys, and is closely related to the big-footed mouse (Macrotarsomys). It is found in the highlands of eastern Madagascar. A small mouse-like rodent, it is dark brown on the upperparts and dark gray below. It has small, rounded, densely haired ears and broad feet with well-developed pads. The long tail lacks a tuft at the tip. The skull is delicate and lacks crests and ridges on its roof.

<span class="mw-page-title-main">Petter's big-footed mouse</span> Species of Madagascan rodent

Petter's big-footed mouse, is a Madagascan rodent in the genus Macrotarsomys. With a head and body length of 150 mm (5.9 in) and body mass of 105 g (3.7 oz), it is the largest species of its genus. Its upper body is brown, darkest in the middle of the back, and the lower body is white to yellowish. The animal has long whiskers, short forelimbs, and long hindfeet. The tail ends in a prominent tuft of long, light hairs. The skull is robust and the molars are low-crowned and cuspidate.

Petter's tufted-tailed rat 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. It is threatened by destruction and fragmentation of its habitat and is listed as "Vulnerable" on the IUCN Red List.

References

  1. 1 2 3 4 5 Kennerley, R. (2019). "Voalavo antsahabensis". IUCN Red List of Threatened Species . 2019: e.T165925A22236108. doi: 10.2305/IUCN.UK.2019-1.RLTS.T165925A22236108.en . Retrieved 19 November 2021.
  2. Goodman et al., 2005, p. 863
  3. 1 2 Goodman et al., 2005, p. 871
  4. 1 2 3 4 Goodman et al., 2005, p. 870
  5. Goodman et al., 2005, pp. 865–866
  6. Goodman et al., 2005, pp. 868–869
  7. 1 2 Goodman et al., 2005, p. 868
  8. 1 2 Goodman et al., 2005, table 1
  9. Goodman et al., 2005, p. 869
  10. Goodman et al., 2005, p. 866
  11. Goodman et al., 2005, p. 872

Literature cited