Relationships
The German mammalogist Hans Rümmler placed this rodent (and Parahydromys asper ) in Hydromys , [7] but that has not been accepted generally. Lidicker (1968), who studies the morphology of the phallus of New Guinea rodents, speculated that Crossomys might not be as closely related to Hydromys as was then generally thought. [8] Later on, this was supported by the immunological study of Watts & Baverstock (1994). [9] This study placed Crossomys closer to Leptomys, Pseudohydromys and Xeromys than to Hydromys.
The American mammalogists Guy Musser and Michael Carleton, in their contribution to the authoritative Mammal Species of the World (3rd ed.), divided the group of murine rodents that had before been called "Hydromyinae" or "Hydromyini" in two "divisions": [10] the Xeromys Division (Leptomys, Pseudohydromys and Xeromys) and the Hydromys Division (Crossomys, Hydromys, Microhydromys, Paraleptomys and Parahydromys[Baiyankamys was added later [2] ]). According to them, the morphology of Crossomys is more like the Hydromys Division than the Xeromys Division, and therefore they placed it in the Hydromys group. They supported their opinion with an unpublished study of the Australian biologist Ken Aplin, who also placed Crossomys closer to Hydromys.
Helgen (2005) concluded that Crossomys is most closely related to Baiyankamys, which had usually been placed in Hydromys before. Baiyankamys has not been studied genetically. According to his data, the Crossomys-Baiyankamys group is most closely related to Hydromys and Parahydromys, though he did not give material to support his opinion. [2]
Characteristics
The earless water rat is adapted best to a life in water out of all the muroids. It has extremely long hindfeet, the toes of which are webbed completely, strongly reduced forelegs, absent or invisible ears, very small eyes, and a long tail with a row of hairs at the downside. That row starts at each side of the beginning of the tail as a long white row of hairs; these two rows merge at about 50 mm from the beginning of the tail and the row goes on to the end of the tail. In all these characters, it resembles the elegant water shrew (Nectogale elegans), a good example of convergent evolution. [2] [6] [11]
The back is greyish brown, and the belly is white. The fur is soft and waterproof. The top half of the tail is light grey, and the bottom half is white. The forefeet and claws are very small, but the hindfeet are very large. The upper lip contains a row of short, strong brushes, which may be used for rasping. The external ear (the pinna) is reduced to a small oval that does not or hardly protract above the fur. It is possible that the ear canal can be closed. The brain is rather large, like in many aquatic animals. The nasals are relatively small, just like the palate and the molars. The bullae are small. The rostrum is narrow. The earless water rat is a medium-sized rat, about as large as its close relative Baiyankamys . [2] [12] The head-body length is 175 to 200 mm (6.9 to 7.9 in) (based on four specimens), tail length is 212 to 260 mm (8.3 to 10.2 in) (4), hind foot length is 44 to 53 mm (1.7 to 2.1 in) (4), ear length is 1 to 45 mm (0.039 to 1.772 in) (2), and weight 165 g (5.8 ounce avoirdupois) (1). [6] Females have 0+2=4 mammae (no thoracic and two inguinal pairs), the same number as most other Australasian rodents. [6]
The earless water rat and Baiyankamys are related because they share the following characters: tail much longer than head-body length; soft, thick, greyish dorsal coat; long, narrow rostrum with a narrow top; very narrow canines; very narrow mesopterygoid fossae; narrow zygomatic arches with a high squamosal root. B. habbema also has the reduced external ears of the earless water rat. [2]
Distribution, habitat and behavior
This animal lives at 1000 to 2700 meters in elevation in Central Cordillera of Papua New Guinea, including the Huon peninsula. The cold, fast-flowing streams of the mountains are its habitat. [6]
During the day it is actively hunting for tadpoles, worms, and river insects (mostly larvae), but at night it sleeps in holes along the river bank. The animal gets only one young at the same time. It is only captured by Telefol hunters when river levels are low. [6]
It is called kwypep by the Kalam tribe (Madang Province), possibly ogoyam in the Telefol language (in Sandaun Province) and momo by the Rofaifo (Southern Highlands Province), although that name is also used for other water rats, like the common Rakali. Some local names can be translated as "water sugar glider", which refers to the similarity of the fur of these two species. [6]
Little is known about the conservation status of this species, although it has the status "least concern" in the IUCN Red List. [1]
Michael Rogers Oldfield Thomas was a British zoologist.
The Old World rats and mice, part of the subfamily Murinae in the family Muridae, comprise at least 519 species. Members of this subfamily are called murines. In terms of species richness, this subfamily is larger than all mammal families except the Cricetidae and Muridae, and is larger than all mammal orders except the bats and the remainder of the rodents.
The rakali, also known as the rabe, the "Australian Otter" or water-rat, is an Australian native rodent first scientifically described in 1804. Adoption of the Ngarrindjeri name rakali is intended to foster a positive public attitude by Environment Australia.
The New Guinea waterside rat is the only species in the genus Parahydromys. It is considered part of the New Guinea Old Endemics, meaning its ancestors were part of the first wave of murine rodents to colonize the island. It is commonly called the "Guinea rat".
The giant white-tailed rat is an Australian rodent native to tropical rainforest of north Queensland, with subspecies occurring in New Guinea and the Aru Islands. It is one of the largest rodents in Australia, reaching up to 1 kg in weight. It is grey-brown above, cream to white below, and has a long, naked tail of which the distal section is white.
Hydromys is a genus of semiaquatic rodents in the subfamily Murinae. Three species are endemic to New Guinea and nearby islands. The fourth species, the rakali, is also found on Australia. The most recently discovered member of this genus was described in 2005.
Water rat(s) may refer to:
Shaw Mayer's water rat is a semiaquatic species of rodent in the family Muridae. It is found in the mountains of Papua New Guinea.
Ernst Mayr's water rat is a species of rodent in the family Muridae, named for evolutionary biologist Ernst Mayr. It is found in the Foja Mountains of Papua Province, Indonesia, and in the mountains of northeastern Papua New Guinea.
Lorentz's mosaic-tailed rat is a species of rodent in the family Muridae. It is found in West Papua, Indonesia and Papua New Guinea. The rat is named after Hendrikus Albertus Lorentz, a Dutch explorer who passed through Lorentz National Park on his 1909–10 expedition.
The black-tailed mosaic-tailed rat is a species of rodent in the family Muridae. It is endemic to the island of New Guinea.
Xeromys myoides, also known as the water mouse, marine mouse, mangrove mouse, false water rat, manngay and yirrkoo, is a species of rodent native to waterways of Australia and Papua New Guinea.
German's one-toothed moss mouse is a species of rodent in the family Muridae which occurs in the mountains of southeastern New Guinea.
The Central Range montane rain forests is a tropical moist forest ecoregion on the island of New Guinea. The ecoregion covers the Central Range of the New Guinea Highlands, which extends along the spine of the island. The montane rain forests of the ecoregion are distinct from the surrounding lowland forests, and are home to many endemic plants and animals.
Ziegler's water rat, described in the mid-2000s, is a semiaquatic species of rodent native to the mountains Papua New Guinea of which little is known.
Kalam is a Kalam language of Papua New Guinea. It is closely related to Kobon, and shares many of the features of that language. Kalam is spoken in Middle Ramu District of Madang Province and in Mount Hagen District of Western Highlands Province.
Baiyankamys is a genus of amphibious murid rodents. It was originally described, along with the species Baiyankamys shawmayeri by Hinton in 1943 after he found the remains of a single individual in south east of the Bismarck Mountain Range, north east New Guinea. Tate, in 1951 and, Laurie and Hill in 1954, confirmed the existence of both the species and genus.
Laurie’s moss mouse is a species of mouse belonging to the family Muridae that is endemic to Papua New Guinea. It was first described in 2009.
Hydromyini is a very large, diverse tribe of muroid rodents in the subfamily Murinae. They are the dominant native rodents in Australasia and one of only two native rodent groups there, the other being the R. fuscipes group of the genus Rattus in the tribe Rattini. They are also found in parts of Southeast Asia.
This page is based on this
Wikipedia article Text is available under the
CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.
