This species is endemic to Madagascar. It occurs in the eastern humid forest and central highlands. This species has only been recorded from a few localities in Madagascar (10 sites listed in Benstead and Olson 2003), including the Antsanpandrano Forestry Station on the Ankarata Massif, a site 15 km north of Antanifotsy village (Andringitra), a site 10 km north of Andekaleka, one specimen was caught in an eel trap at Ranomafana Est, 60 km east of Fianarantsoa; and a site 35 km south of Antsirabe. Its amphibious lifestyle is an impediment to the study of its distribution, which is poorly known. The altitudinal range is 450–2,000 m. There have not been many appropriate surveys in the intervening areas between the known localities, though it is likely present in appropriate habitat.

L. mergulus is found only in eastern Madagascar's high altitude stream and marsh regions.

Biogeographic Regions: ethiopian (Native )

The fur is short, dense, and soft, with a texture similar to that of an otter. L. mergulus is brown in color, but also has hairs of red and black appearance interspersed. The underbelly is pale yellowish gray. The skin of this species is black on the dorsal surface and gray on the ventral surface. The head is small and broad compared to the body, and it has a flattened appearance. The slightly blunt muzzle is covered in short vibrissae that are a very effective sense organ. The eyes and ears are also small. In fact, the fur nearly covers the ears, perhaps as an aquatic adaptation. L. mergulus also has webbed toes (thus its common name) and a thick powerful tail to aid in swimming. It has recently been observed that the hind feet are the primary mode of propulsion with the tail acting as a rudder. The tail is approximately 61-119 mm long, accounting for almost half the length of the animal, and has a square shape. The fringed forefeet are used mostly to hold captured prey for consumption. L. mergulus has a true cloaca and it has also been noted that the testes of the male never descend from the body into a scrotum, instead remaining in the abdominal cavity. The dental formula is 3/3,1/1,3/3,3/3.

Range mass: 80 to 100 g.

Range length: 130 to 240 mm.

Habitat and Ecology

Systems

• Freshwater

L. mergulus is found only in regions of fast-flowing streams on steep sloping cliffs and highlands. These regions may either be forested or not. Currently, there are only ten known sites that have supported this species; however, it may have disappeared from two due to habitat destruction.

Range elevation: 450 to 2000 m.

Habitat Regions: terrestrial

Terrestrial Biomes: forest ; rainforest

Aquatic Biomes: rivers and streams

L. mergulus is a stictly nocturnal, aquatic forager, using its vibrissae and sweeping motions of the head to search the stream bed for prey. After prey are captured using the mouth, they are brought to the surface, where L. mergulus rolls on its back and kicks the prey into submission using its hind feet. Prey are then brought to shore or to a rock, grasped with the forefeet and consumed in bites. Insects, both larval and adult, are the dominate prey; however, diet varies by stream. They also eat larval anurans (small frogs), and crayfish.

Animal Foods: reptiles; insects; terrestrial non-insect arthropods

Primary Diet: carnivore (Insectivore )

L. mergulus may be important in the control of certain insect populations.

Limnogale mergulus preys on:
Arthropoda
Insecta
Reptilia

This list may not be complete but is based on published studies.

While there has been little research, breeding is thought to take place in December and January, resulting in an approximate litter size of three. Females possess six mammae. The gestation period is unknown.

Breeding season: December to January (speculative)

Average number of offspring: 3.

Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); viviparous

Year Assessed

Assessor/s

Reviewer/s

Justification

History

• 2006
  Vulnerable
  (IUCN 2006)
• 1996
  Endangered
• 1994
  Indeterminate
  (Groombridge 1994)
• 1990
  Indeterminate
  (IUCN 1990)
• 1988
  Vulnerable
  (IUCN Conservation Monitoring Centre 1988)

The endangered status of L.mergulus is as a result of loss of habitat due to human expansion. It is thought that by protecting new and existing sites, we can protect the food source of this species, thereby protecting the species itself.

US Federal List: endangered

CITES: no special status

IUCN Red List of Threatened Species: vulnerable

Population

Population Trend

Major Threats

Conservation Actions

L. mergulus feeds on insect larvae that may act as pests to humans.