Notoryctes caurinus, Thomas, 1920

Russell A. Mittermeier & Don E. Wilson, 2015, Notoryctidae, Handbook of the Mammals of the World – Volume 5 Monotremes and Marsupials, Barcelona: Lynx Edicions, pp. 210-219 : 218

1 .

North-western Marsupial Mole

Notoryctes caurinus

French: Kakarratul / German: Kleiner Beutelmull / Spanish: Topo marsupial septentrional

Other common names: Kakarratul, Northern Marsupial Mole, Western Marsupial Mole

Taxonomy. Notoryctes caurinus Thomas, 1920 ,

“ Wollal [= Wallal] , N.W. Australia.”

This species is monotypic.

Distribution. Sandy deserts of NW Australia (Western Australia), including Gibson, Little Sandy, and Great Sandy deserts, and possibly parts of the Tanami Desert, and approaching the coast in the hinterland of the Eighty Mile Beach between Port Hedland and Broome.

Descriptive notes. Head-body 8.6-9.3 cm, tail 1.6-1.8 cm; weight 30-50 g. The North-western Marsupial Mole is slightly smaller and of more slender build than its relative, the Central Desert Marsupial Mole ( N. typhlops ). Two large claws on forelimb of the North-western Marsupial Mole are consistently narrower, rhinarial pad is smaller in height and width, and tail is narrower at its base. Cranium of the North-western Marsupial Mole is smaller than that of the Central Desert Marsupial Mole and has a proportionally shorter rostrum and larger auditory bullae. In upper dentition of the North-western Marsupial Mole, last molar (M*) is more reduced in size and complexity than in the Central Desert Marsupial Mole. Lower dentition features a reduction in tooth number in incisor-to-premolar region, with three small, single-rooted teeth present rather than 4-5 teeth. Notable features of postcranial anatomy of the North-western Marsupial Mole include a reduced number of ribs (14 rather than 15 in the Central Desert Marsupial Mole), a loss of one sternal segment (five rather than six sternebrae between manubrium and ziphoid cartilage), and an even greater reduction of epipubic element to thin cartilaginous rod (small but ossified in the Central Desert Marsupial Mole).

Habitat. Sandy habitats including extensive tracts of linear dune-field, areas of parabolic dune complexes, and sandy washouts of ephemeral watercourses, with spinifex ( Triodia , Poaceae ) hummock grassland and a variable shrub layer of acacias ( Acacia , Fabaceae ) and other woody plants. The North-western Marsupial Mole has been collected at fewer than 15 localities in Gibson, Little Sandy, and Great Sandy deserts of Western Australia; however, information from Aboriginal informants suggests a much broader distribution that probably takes in ¢.30% of the land area of Western Australia—a huge and largely unpopulated area. At the south-eastern extremity of its distribution,in the vicinity of the Warburton Range, the North-western Marsupial Mole may occur in regional sympatry or syntopy with the Central Desert Marsupial Mole.

Food and Feeding. The diet of the North-western Marsupial Mole has not been studied either in the field or from examination of gut contents. A captive individual held in the laboratory of P. Withers of the University of Western Australia initially proved difficult to maintain, although it later seemed to feed avidly on large insect larvae collected from the stems of dead grass trees (Xanthorrhoea sp., Xanthorrhoeaceae ). Mealworm larvae ( Tenebrio molitor , Tenebrionidae ) were refused. The individual inexplicably stopped eating and died after five weeks in captivity.

Breeding. There is no specific information available for this species, but if the specimen in the South Australian Museum from Sturt Creek in Western Australia is a Northwestern Marsupial Mole, then it provides a record of twin pouch young.

Activity patterns. The only information on activity patterns of the North-western Marsupial Mole comes from observations on a single captive individual that was maintained for five weeks. Its general behavior conformed to reports on captive Central Desert Marsupial Moles. Whether above or below the surface, it alternated between bouts of frenetic activity and periods of immobility during which it appeared to be asleep. When brought to the surface, it usually burrowed again rapidly.

Movements, Home range and Social organization. Trackways made by the Northwestern Marsupial Mole lack central tail drag mark, and it is assumed that they hold the tail off the ground while walking or running. More detailed information on locomotion and burrowing ability come from observations on a single captive individual. This individual was unable to burrow into dry sand because any excavation filled with sand as fast as it was removed. Burrowing became possible only when sand was moistened, thereby providing some cohesion. During initial burrowing, the tail was used to brace the body as head and forelimbs were plunged downward into the sand. When placed in an experimental rotating chamber full of dry sand, the individual could sand-swim successfully. Energetic cost of sand swimming is similar for the North-western Marsupial Mole (81 J/m) and the Namib Golden Mole ( Eremitalpa granti namibensis ; 73 J/m), which shows a high degree of morphologically convergence. Nevertheless, the Namib Desert Golden Mole burrows through sand considerably faster (15-40 m/h) than the marsupial mole (2-18 m/h), which is thus a relatively inefficient sand swimmer under the test conditions. Withers and coworkers described the surface gait of the captive North-western Marsupial Mole as “a slow and seemingly laborious shuffling action.” Nevertheless, running could be maintained for more than 60 minutes at a remarkably constant average speed of 484 m/h (range = 319-688 m/h). Metabolic rate of the marsupial mole was similar whether it was running or sand swimming. Because much higher speeds were achieved during surface running than during sand swimming, the former is a much more energy efficient (1-4 J/m compared to 81 J/m for sand swimming). If these values are at all representative of the natural energetic regime of a free-living marsupial mole,it can only be presume that individuals are able to encounter prey items in sufficiently quantities below ground and, furthermore, that this “high-cost” lifestyle is rewarded by safety from predation. Nevertheless, sand swimming along sand-filled tunnels may require much less energy if an individual is able to obtain purchase on the walls or roof of the tunnel through use of its front claws, tail, and ischiotergal patch on its lower back. No information is available on home range or social organization of the North-western Marsupial Mole.

Status and Conservation. Classified as Data Deficient on The IUCN Red List. A recent assessment by A. Burbidge and coworkers in 2014 recommends a conservation status of Least Concern. Each known locality for the North-western Marsupial Mole has yielded only 1-2 specimens, and there is nothing to match the large singlelocality samples available for the Central Desert Marsupial Mole. While this might reflect a genuine ecological contrast in abundances between the two species,it is more prudent to conclude that it represents circumstances of collecting. All capture records of North-western Marsupial Moles since 1990 come from localities in the north-western part of its distribution. This is an area of active resource development, and several North-western Marsupial Moles have been uncovered during road construction.

Bibliography. Benshemesh (2004), Benshemesh & Aplin (2008), Benshemesh & Burbidge (2008), Burbidge & Aplin (1996), Burbidge et al. (1988), Maxwell et al. (1996), Thomas (1920b), Thompson et al. (2000), Troughton (1973), Warburton (2006), Warburton et al. (2003), Withers et al. (2000), Woinarski et al. (2014bd).

Figures

Plate 13 Species Accounts

Distribution. Sandy deserts of NW Australia (Western Australia), including Gibson, Little Sandy, and Great Sandy deserts, and possibly parts of the Tanami Desert, and approaching the coast in the hinterland of the Eighty Mile Beach between Port Hedland and Broome.