Microgale mergulus, Major, 1896

Russell A. Mittermeier & Don E. Wilson, 2018, Tenrecidae, Handbook of the Mammals of the World – Volume 8 Insectivores, Sloths and Colugos, Barcelona: Lynx Edicions, pp. 134-172 : 171

27.

Web-footed Tenrec

Microgale mergulus

French: Microgale plongeur / German: Wassertenrek / Spanish: Tenrec musarana de pies palmeados

Other common names: Aquatic Tenrec, Otter Shrew

Taxonomy. Limnogale mergulus Major, 1896 ,

“Imasindrary, N.E. Betsileo,” Madagascar. Clarified by P. D. Jenkins and M. D. Carleton in 2005 to “Masindrary; 20°17°S 47°31’'E.”

Limnogale was considered a sister taxon to Micropotamogale and Potamogale based on morphology; however, combined molecular and morphological analyses and molecular analyses showed that it is most closely related to the Oryzorictinae and that apparent similarities in morphology to that of potamogalids was due to convergent evolution related to their semi-aquatic lifestyles. The most recent comprehensive molecular phylogenetic analysis revealed that mergulus is not in a distinct genus butis a species of Microgale and, furthermore, most closely related to the smallest species, M. parvula . Monotypic.

Distribution. Central Highlands and E Madagascar; populations are likely to be disjunct.

Descriptive notes. Head-body 116-170 mm, tail 128-161 mm, ear 9-13 mm, hindfoot 30-36 mm; weight 60-110 g. The Web-footed Tenrec is the largest species of Oryzorictinae . Pelage is dense, short, and soft; dorsum is brown to dark brown, with reddish and yellowish tips to hairs and long black guard hairs; and hairs on rump and base oftail have silvery tips. Venter is pale gray or yellowish brown, with silvery sheen. Tail is stout proximally, laterally compressed distally, and brown above with dark hairs covering scales and longer buffy white hairs on lateral and ventral surfaces. Head is short, broad, and flattened; muzzle is blunt, with pronounced mystacial vibrissae; rhinarium is broad, with nostrils positioned dorso-laterally; philtrum is well developed; eyes are small; and ears are nearly hidden in fur. Digits of forefeet and hindfeet are extensively webbed, and hindfeet are fringed with stiff, light-colored hair.

Habitat. Fast-flowing streams in humid forests, including degraded habitats and rivers bordered by non-native tree plantations,at elevations of 450-2000 m.

Food and Feeding. Web-footed Tenrec’s fecal pellets from six streams in and near Ranomafana National Park contained a preponderance of aquatic insect larvae, particularly Ephemeroptera, Odonata, and Trichoptera larvae and small amounts of crayfish and anuran larvae. Small frogs,fish, freshwater crabs, and freshwater shrimp were also found in other analyses of stomach contents.

Breeding. There is a record of two young Web-footed Tenrecs in a nest and a lactating female captured in December.

Activity patterns. Web-footed Tenrecs are semi-aquatic, terrestrial, and nocturnal, generally emerging from their burrows near sunset and returning before sunrise. Activity during this time was variable; sometimes individuals were active all night, but on other occasions, they returned to their burrows intermittently for short or long periods. Most activity occurred in water. At Ranomafana, Web-footed Tenrecs are apparently active year-round, but there is some anecdotal evidence that maximum activity occurs during austral summer.

Movements, Home range and Social organization. There is little specific information on social behavior, but prominent latrine sites on logs and boulders along streams might indicate territorial behavior. Total estimated home ranges equivalent to the area of the streambed of two radio-tracked Web-footed Tenrecs were 6960 m* and 7070 m®.

Status and Conservation. Classified as Vulnerable on The IUCN Red List (as Limnogale mergulus ). The Web-footed Tenrec is poorly known, recorded from only ten localities over a wide area of the eastern humid forest and Central Highlands, where it is restricted to clean, fast-flowing streams within natural forest and has an estimated area of occupancy of only 2000 km?. It is threatened by habitat degradation, deforestation causing silting and soil erosion, forest fragmentation isolating suitable riverine habitat, and accidental capture in fish traps. Overall population of the Web-footed Tenrec is probably decreasing because it no longer occurs or is rare at sites where it has been previously recorded.

Bibliography. Asher (1999), Asher & Hofreiter (2006), Benstead & Olson (2003), Benstead et al. (2001), Eisenberg & Gould (1970), Everson et al. (2016), Goodman et al. (2013), Jenkins & Carleton (2005), Malzy (1965), Olson & Goodman (2003), Poux et al. (2005), Salton & Sargis (2008a, 2008b, 2009), Stephenson et al. (2016).

Figures

1. Lesser Hedgehog Tenrec (Echinops telfairi), 2. Greater Hedgehog Tenrec (Setifer setosus), 3. Tailless Tenrec (Tenrec ecaudatus), 4. Lowland Streaked Tenrec (Hemacenteles semispinosus), 5. Highland Streaked Tenrec (Hemicentetes nigriceps), 6. Large-eared Tenrec (Geogale aurita), 7. Mole-like Rice Tenrec (Oryzorictes hova), 8. Four-toed Rice Tenrec (Oryzorictes tetradactylus), 9. Dobson’s Shrew Tenrec (Nesogale dobsoni), 10. Talazac’s Shrew Tenrec (Nesogale talazact), 11. Montane Shrew Tenrec (Macrogale monticola), 12. Dryad Shrew Tenrec (Microgale dryas), 13. Short-tailed Shrew Tenrec (Microgale brevicaudata), 14. Pygmy Shrew Tenrec (Microgale parvula), 15. Lesser Long-tailed Shrew Tenrec (Mucrogale longicaudata), 16. Drouhard’s Shrew Tenrec (Microgale drouhardi), 17. Taiva Shrew Tenrec (Microgale taiva), 18. Pale Shrew (Tenrec Mucrogalefotsifotsy), 19. Greater Long-tailed Shrew Tenrec (Microgale principula), 20. Cowan's Shrew Tenrec (Microgale cowant), 21. Naked-nosed Shrew Tenrec (Microgale gymnorhyncha), 22. Shrew-toothed Shrew Tenrec (Microgale soricoides), 23. Major's Shrew Tenrec (Microgale major), 24. Gracile Shrew Tenrec (Microgale gracilis), 25. Thomas’s Shrew Tenrec (Microgale thomasi), 26. Grandidier’s Shrew Tenrec (Muicrogale grandidieri), 27. Web-footed Tenrec (Microgale mergulus), 28. Least Shrew Tenrec (Muicrogale pusilla), 29. Dark Shrew (Tenrec Microgalejobihely), 30. Nasolo’s Shrew Tenrec (Microgale nasoloi), 31. Jenkins’s Shrew (Tenrec Microgalejenkinsae)

Distribution. Central Highlands and E Madagascar; populations are likely to be disjunct.