Dwarf Manatee
Encyclopedia
The Dwarf Manatee is a possible species of manatee
that lives in the freshwater habitats of the Amazon
, though restricted to one tributary
of the Aripuanã River
. According to Marc van Roosmalen
, the scientist who proposes it as a new species, it lives in shallow, fast running water and feeds on different species of aquatic plants than the Amazonian Manatee
, which prefers deeper slower moving waters and the plants found there. It is reported that the dwarf manatees migrate upriver during the rainy season when the river floods to the headwaters and shallow ponds. Based on its small range, it has been suggested that the Dwarf Manatee is critically endangered
, but at present it is not recognized by the IUCN.
Dwarf Manatees are typically about 130 cm long, and weigh about 60 kg, making them the smallest extant sirenians. It is overall very dark, almost black, with a white patch on the abdomen
. It has been suggested that it actually represents an immature Amazonian Manatee, but they are reported to differ in proportions and colour. They are, however, at least very closely related, as mtDNA has failed to reveal any difference between the two. Based on mutation rate
s in manatees – if the Dwarf Manatee is distinct – this suggests a divergence
time of less than 485,000 years. Daryl Domning, a Smithsonian Institution
research associate and the world's foremost experts on manatee evolution
, has stated that the DNA evidence actually proves that these merely are immature Amazonian Manatees.
Disregarding its questionable validity as a species, the proposed name "Trichechus pygmaeus" is problematic. A formal description using that name was submitted to Nature
, but it was rejected and consequently the article has only been published online. This has resulted in the invalidation of the name following chapter 3, article 8 of the ICZN Code
.
Manatee
Manatees are large, fully aquatic, mostly herbivorous marine mammals sometimes known as sea cows...
that lives in the freshwater habitats of the Amazon
Amazon Rainforest
The Amazon Rainforest , also known in English as Amazonia or the Amazon Jungle, is a moist broadleaf forest that covers most of the Amazon Basin of South America...
, though restricted to one tributary
Tributary
A tributary or affluent is a stream or river that flows into a main stem river or a lake. A tributary does not flow directly into a sea or ocean...
of the Aripuanã River
Aripuanã River
Aripuanã River is a river of Amazonas and Mato Grosso states in north-western Brazil.-See also:*List of rivers of Amazonas*List of rivers of Mato Grosso-References:*...
. According to Marc van Roosmalen
Marc van Roosmalen
Dr. Marc van Roosmalen is a Brazilian primatologist of Dutch birth living in Manaus in Brazil. He was elected as one of the "Heroes of the Planet" by Time Magazine in 2000...
, the scientist who proposes it as a new species, it lives in shallow, fast running water and feeds on different species of aquatic plants than the Amazonian Manatee
Amazonian Manatee
The Amazonian Manatee is a species of manatee that lives in the freshwater habitats of the Amazon basin. They are found in Brazil, Peru, Colombia, Ecuador, Guyana and Venezuela. Amazonian manatees are aquatic animals of the Sirenia order and are also known as "seacows". Their colour is grey but...
, which prefers deeper slower moving waters and the plants found there. It is reported that the dwarf manatees migrate upriver during the rainy season when the river floods to the headwaters and shallow ponds. Based on its small range, it has been suggested that the Dwarf Manatee is critically endangered
Critically endangered
Version 2010.3 of the IUCN Red List of Threatened Species identified 3744 Critically Endangered species, subspecies and varieties, stocks and subpopulations.Critically Endangered by kingdom:*1993 Animalia*2 Fungi*1745 Plantae*4 Protista-References:...
, but at present it is not recognized by the IUCN.
Dwarf Manatees are typically about 130 cm long, and weigh about 60 kg, making them the smallest extant sirenians. It is overall very dark, almost black, with a white patch on the abdomen
Abdomen
In vertebrates such as mammals the abdomen constitutes the part of the body between the thorax and pelvis. The region enclosed by the abdomen is termed the abdominal cavity...
. It has been suggested that it actually represents an immature Amazonian Manatee, but they are reported to differ in proportions and colour. They are, however, at least very closely related, as mtDNA has failed to reveal any difference between the two. Based on mutation rate
Mutation rate
In genetics, the mutation rate is the chance of a mutation occurring in an organism or gene in each generation...
s in manatees – if the Dwarf Manatee is distinct – this suggests a divergence
Genetic divergence
Genetic divergence is the process in which two or more populations of an ancestral species accumulate independent genetic changes through time, often after the populations have become reproductively isolated for some period of time...
time of less than 485,000 years. Daryl Domning, a Smithsonian Institution
Smithsonian Institution
The Smithsonian Institution is an educational and research institute and associated museum complex, administered and funded by the government of the United States and by funds from its endowment, contributions, and profits from its retail operations, concessions, licensing activities, and magazines...
research associate and the world's foremost experts on manatee evolution
Evolution of sirenians
Sirenia is the order of placental mammals which comprise modern "sea cows" and their extinct relatives. They are the only extant herbivorous marine mammals and the only group of herbivorous mammals to have become completely aquatic. Sirenians are thought to have a 50-million-year-old fossil record...
, has stated that the DNA evidence actually proves that these merely are immature Amazonian Manatees.
Disregarding its questionable validity as a species, the proposed name "Trichechus pygmaeus" is problematic. A formal description using that name was submitted to Nature
Nature (journal)
Nature, first published on 4 November 1869, is ranked the world's most cited interdisciplinary scientific journal by the Science Edition of the 2010 Journal Citation Reports...
, but it was rejected and consequently the article has only been published online. This has resulted in the invalidation of the name following chapter 3, article 8 of the ICZN Code
International Code of Zoological Nomenclature
The International Code of Zoological Nomenclature is a widely accepted convention in zoology that rules the formal scientific naming of organisms treated as animals...
.
External links
- Cryptomundo - Dwarf Manatee)
- Tetrapodzoology - new species of large, living mammal (part II))
- Wildlife Extra