Sminthopsis macroura (Gould, 1845)

Russell A. Mittermeier & Don E. Wilson, 2015, Dasyuridae, Handbook of the Mammals of the World – Volume 5 Monotremes and Marsupials, Barcelona: Lynx Edicions, pp. 232-348 : 344

69.

Stripe-faced Dunnart

Sminthopsis macroura

French: Dunnart a face rayée / German: Streifgesichtige Schmalfufl 3beutelmaus / Spanish: Raton marsupial de cara rayada

Other common names: Darling Downs Dunnart, Froggatt's Sminthopsis, Larapinta, Stripe-headed Sminthopsis

Taxonomy. Podabrus macrourus Gould, 1845 ,

Darling Downs, Queensland, Australia.

Phylogenetic relationships among the 28 species in the clade Sminthopsinae have been investigated in several morphological and molecular studies. A recent genetic phylogeny (several mitochondrial and nuclear genes) failed to support monophyly of the genus Sminthopsis with respect to Antechinomys and Ningawi. There were three deeply divergent clades of Sminthopsis . In the first, S. longicaudata was sister to A. laniger . A second clade was composed of the traditional morphologically based Macroura Group: five Sminthopsis comprised a strongly supported clade that included S. erassicaudata , S. bindi , S. macroura , S. douglasi , and S. virginiae . Individuals of S. macroura show considerable morphological variability throughout the species’ extensive distribution, particularly in body size, color, and tail length. Such geographical variation originally led to the recognition of a number of species, such as Podabrus macrourus by J. Gould in 1845; Antechinus (Podabrus) froggatti by E. P. Ramsay in 1887; Sminthopsis larapinta by W. B. Spencer in 1896; S. stalker: by O. Thomas in 1906; and S. monticola by E. Le G. Troughton in 1965. Following description, each taxon received little comparative treatment. M. Archer, in his generic review, found no consistent cranial or dental characters that distinguished the various forms, so he synonymized them with S. macroura , suggesting use of two names for populations of S. macroura , although he did not statistically assess their morphology. The nominate form, macroura , is found at the eastern limit of the species’ distribution; the subspecies froggatti (composed of “froggatti,” “larapinta,” and “stalker?” forms of earlier authors) occurs across most of arid inland Australia. He also noted another form of S. macroura known only from Doomadgee Mission in north-western Queensland. Genetic studies more than a decade old suggest that S. macroura comprises three distinct species that began divergence several million years ago. Specimens of S. macroura (currently recognized) belong to three highly genetically distinct lineages. Two of these lineages may be synonymous with two previously recognized dunnart species: S. froggatti and S. stalkeri. The third lineage apparently represents “true” S. macroura but is itself genetically heterogeneous, possibly containing unrecognized taxa. These three taxa may well warrant species-level listing, but the situation is confused. They are listed as subspecies here but their status should be regarded as fluid. Three subspecies recognized.

Subspecies and Distribution.

S.m.macrouraGould,1845—C,E,W&SAustralia.

S.m.froggattiRamsay,1887—KimberleyregioninNWesternTerritory.

S. m. stalker: Thomas, 1906 — CN Australia.

Descriptive notes. Head—body 7-10 cm,tail 8-11 cm; weight 15-25 g. The Stripe-faced Dunnart can be distinguished from other dunnarts by length of its usually fat tail, which is c.1-2times head-body length, and its prominent line of dark hair extending from between eyes to between ears. Interdigital hindfoot pads have a distinctly enlarged apical granule surrounded by a number ofslightly enlarged granules. Two distinct color morphs, pale gray-brown and gray.

Habitat. Vast inland areas in arid and semi-arid central and northern Australia. Accordingly, Stripe-faced Dunnarts are found in many habitats in this broadly arid region, such as low shrublands of saltbush and bluebush; tussock grasslands on clay, sandy, or stony soils; spinifex ( Triodia spp. , Poaceae ) grasslands on sandy soils; among sparse Acacia (Fabaceae) shrublands; on open salt lakes; and among low, shrubby, rocky ridges. Densest populations of Stripe-faced Dunnarts evidently occur in shrubland and tussock grasslands where grazing by livestock is sparse or absent.

Food and Feeding. Stripe-faced Dunnarts eat mostly invertebrates, except ants; occasionally they will eat other small mammals and lizards. They are almost certainly not reliant on drinking water, and extensive fat stores in their long tails provide an energy reserve that may be used in times of food shortage.

Breeding. In captivity, female Stripe-faced Dunnarts come into estrus in June-February; most individuals can raise at least two litters. Gestation is a mere eleven days—the shortest known for any marsupial. Female young born early (before mid-October) mature in the season of their birth at 86-159 days old; those born later mature in the following season at 185-262 days old. Minimum body weight at sexual maturity is 12-5 g. At least two litters can be reared in a season, and individuals may breed in more than one season. The Stripe-faced Dunnart is polyestrous; it has a mean cycle length of 23-25 days. Females have eight teats that are typically fully occupied; pouch fully encloses newborn young. Females mature at c.4 months old and males at c.9 months. Field studies suggest breeding is confined to the same season as in captivity, with juveniles appearing progressively in populations during summer. Some captive studies have indicated that most males do not reach sexual maturity until the season following that in which they were born, although spermatorrhoea production may commence in the season of birth when a male is 141-350 days old. Minimum scrotal width at which sperm production commences is 7-9 mm, and minimum body weight is 14 g. One study examined growth of young from birth to weaning (65-70 days). Two major phases of growth were recognized. In Phase I from birth to about day 54 postpartum, growth rate was rapid. In Phase II from about day 55 to weaning, a deceleration in growth rate was apparent. Growth rate may have decreased due to regression of mammary tissue associated with commencement of weaning. In this study, no significant relationship was found between month of birth and growth rate; there was evidence that litters of different sizes grew at varying rates during Phase II of the suckling period.

Activity patterns. Stripe-faced Dunnarts are strictly nocturnal, emerging to forage about an hour after dusk. They avoid high temperatures by sheltering during the day in cracks in soil, under rocks and logs, and even in burrows constructed by other animals such as agamid lizards. In captivity, the Stripe-faced Dunnart may become torpid during the day, especially if food is scarce and ambient temperature falls below 20°C. Body temperatures of Stripe-faced Dunnarts can drop to just 14-15°C during torpor, allowing them to reduce energy needs by 90%. One study found that they maintained fairly consistent body temperature when exposed to varying conditions. Researchers hypothesized that the more constant thermoregulatory strategy of the Stripe-faced Dunnart allows it to exploit a broad climatic range, albeit at the cost of higher energetic and water requirements.

Movements, Home range and Social organization. Nothing is known offluctuations in densities of wild populations of Stripe-faced Dunnarts. Because much ofits distribution lies within areas of highly variable rainfall, population dynamics almost certainly vary from place to place. Rapidity with which previously deserted areas are colonized after rainfall suggests that Stripe-faced Dunnarts, like some other species of Sminthopsis , are quite mobile: overnight movements of 300-2000 m have been recorded in shrubland and spinifex habitats.

Status and Conservation. Classified as Least Concern on The IUCN Red List. The Stripefaced Dunnart has a wide distribution, presumably has a large overall population, occurs in a number of protected areas, and is unlikely to be declining at nearly the rate required to qualify for listing in a threatened IUCN category. There are localized conservation threats from heavy grazing by domestic cattle and sheep, which appears to have played a role in loss of the Stripe-faced Dunnarts in the south-eastern part of its distribution. Nevertheless, the Stripe-faced Dunnart occurs in a number of protected areas, and its status has probably not changed since European settlement. Grazing by domestic stock throughout the interior may have contributed to reducing suitability of the shrubland and tussock grassland that the Stripe-faced Dunnart prefers. It has been lost from the agricultural band of south-eastern New South Wales and Victoria.

Bibliography. Archer (1981a), Baverstock et al. (1984), Blacket, Adams et al. (2001), Blacket, Cooper et al. (2006), Frank & Soderquist (2005), Frigo & Woolley (1997), Gould (1845), Krajewski et al. (2012), McAllan et al. (2012), Morton & Dickman (2008b), Ramsay (1887), Spencer (1896a), Thomas (1906), Troughton (1965b), Tomlinson et al. (2012), Woinarski & Dickman (2008b), Woolley (1990b, 1990c).

Figures

56. Kangaroo Island Dunnart (Sminthopsis aitken), 57. Chestnut Dunnart (Sminthopsis archer), 58. Kakadu Dunnart (Sminthopsis bindi), 59. Butler's Dunnart (Sminthopsis butleri), 60. Fat-tailed Dunnart (Smunthopsis crassicaudata), 61. Little Long-tailed Dunnart (Sminthopsis dolichura), 62. Julia Creek Dunnart (Smunthopsis douglasi), 63. Gilbert's Dunnart (Sminthopsis gilbert), 64. White-tailed Dunnart (Sminthopsis granulipes), 65. Grey-bellied Dunnart (Sminthopsis griseoventer), 66. Greater Hairy-footed Dunnart (Smunthopsis hirtipes), 67. White-footed Dunnart (Sminthopsis leucopus), 68. Greater Long-tailed Dunnart (Sminthopsis longicaudata), 69. Stripe-faced Dunnart (Sminthopsis macroura), 70. Common Dunnart (Sminthopsis murina), 71. Ooldea Dunnart (Sminthopsis ooldea), 72. Sandhill Dunnart (Sminthopsis psammophila), 73. Red-cheeked Dunnart (Sminthopsis virginiae), 74. Lesser Hairy-footed Dunnart (Sminthopsis youngsoni)

Subspecies and Distribution. S.m.macrouraGould,1845—C,E,W&SAustralia. S.m.froggattiRamsay,1887—KimberleyregioninNWesternTerritory. S. m. stalker: Thomas, 1906 — CN Australia.