Sminthopsis aitken, Kitchener, Stoddart & Henry, 1984

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 : 335

56.

Kangaroo Island Dunnart

Sminthopsis aitken

French: Dunnart de Kangaroo / German: Aitkens Schmalful 3beutelmaus / Spanish: Raton marsupial de Kangaroo

Other common names: Sooty Dunnart

Taxonomy. Sminthopsis aitkeni Kitchener, Stoddart & Henry, 1984 ,

Section 46 , Cassini , Kangaroo Island , South Australia, Australia.

In 1888, O. Thomas noted that smaller species in the genus Sminthopsis (dunnarts) are unusually difficult to discriminate because of close resemblance between skulls and teeth of different species. This was acknowledged in later work; in 1981, M. Archer not only heralded twelve species of dunnart but drew attention to several discrete populations and the fact that most recognized species exhibited geographical variations that might constitute different species. Subsequent electrophoretic and direct DNA studies supported his general contention. Sminthopsis is the most speciose genus (currently 19 species) ofliving dasyurid marsupials, and along with its close relatives Antechinomys (one species), Ningawi (three species), and Planigale (five species) constitutes the clade Sminthopsini. Phylogenetic relationships among species in the Sminthopsinae have been the subject of numerous morphological and molecular investigations. Genetic phylogenies (several mitochondrial and nuclear genes) have failed to support monophyly of the genus Sminthopsis with respect to Antechinomys and Ningaui . In a recent study, there were three deeply divergent clades of Sminthopsis . In the first, S. longicaudata was sister to A. laniger (an alliance also obtained from previous morphological analyses, in which there was good reason to include Antechinomys within Sminthopsis and also to link it with S. longicaudata ). The second clade was composed of the traditional morphologically based Macroura Group: five Sminthopsis formed a strongly supported clade that included S. crassicaudata , S. bindi , S. macroura , S. douglasi , and S. virginiae . This clade of five dunnarts wasitself a poorly supported sister to the three species of Ningaui (N. ridei , N. timealeyi , and N. yvonneae). This combined clade of the five Sminthopsis and three Ningaui was positioned as a poorly supported sister to a well-supported clade containing the remainder of Sminthopsis species (13 species in the Murina Group). This large dunnart clade contained a well-supported sister pairing of S. aitkeni and S. griseoventer for all genes used in the analysis. There are clearly many genetic and morphological similarities between S. aitkeni and S. griseoventer ; indeed, some workers have suggested that the two might be conspecific, in which case one of the two (both raised in the same paper by D. J. Kitchener and colleagues in 1984) would need to be subsumed. In April and June 1969, a domestic dog caught two male dunnarts escaping from the base of a recently felled grasstree (Xanthorrhoea semiplana) in low shrub and woodland (mallee) heath, north-central region, Kangaroo Island. These sooty-colored dunnarts were sent to the South Australian Museum, where then Curator of Mammals, P. Aitken, identified them as S. murina , formally noting they represented a new record for Kangaroo Island. In 1984, a numberof distinct forms in the S. murina complex were formally described by Kitchener and colleagues based on morphology, and all these Kangaroo Island specimens were then assigned as a new species, S. aitkeni , in honor of their original founder. Monotypic.

Distribution. Kangaroo I, South Australia.

Descriptive notes. Head-body 8:4.9-3 cm (males) and 7.2-8.2 cm (females), tail 9-10.6 cm (males) and 8:6.9-4 cm (females); weight 20-25 g (males) and 10-15 g (females). There is sexual dimorphism for size. The Kangaroo Island Dunnart has a dark, sooty coat above and pale gray belly. Snout is slender and pointed; tail is always longer than head-body length and never incrassated (fat) at base. Kangaroo Island Dunnarts can be distinguished from the Common Dunnart ( S. murina ) and the Little Long-tailed Dunnart ( S. dolichura ) by blackish rather than brown dorsal fur, gray rather than white belly, and a relatively longertail.

Habitat. Variety of mallee heath vegetation types on lateritic and sandy soils from sea level to elevations of 270 m. The Kangaroo Island Dunnart appears to be a habitat generalist.

Food and Feeding. Kangaroo Island Dunnarts predominantly feed on spiders and ants, with beetles and scorpions taken less frequently.

Breeding. The Kangaroo Island Dunnart appears to be polyestrous, mating in late September and then again in late December, butlittle is known about its specific reproductive biology.

Activity patterns. There is no information available for this species.

Movements, Home range and Social organization. Radio tracking of a few individuals revealed that males moved 290-380 m nightly and females moved 170-180 m.

Status and Conservation. Classified as Critically Endangered on The IUCN Red List. Listed as endangered in Australia. The Kangaroo Island Dunnart is thought to occur in less than 100 km?There is continuing decline in its distribution, quality of its habitat, number of known locations, and number of mature individuals on Kangaroo Island. Since its original discovery, the Kangaroo Island Dunnart has proven very elusive. In more than 17,000 pitfall and 20,000 cage-trap nights on Kangaroo Island, it was captured only 32 times. The Kangaroo Island Dunnart is known to have once occupied a wider area on Kangaroo Island, but it has not been found outside one small area since before 1991, despite extensive survey work; old records are from habitat that appears to be no longer suitable. All captures since 1990 have come from Flinders Chase National Park on the western end of Kangaroo Island. Earlier records of Kangaroo Island Dunnarts indicate they were at the eastern end of the island, but they likely are no longer present there due to habitat modification. Prior to the most recent detailed surveys, Kangaroo Island Dunnarts were known from only seven specimens and three other records. An additional 22 records were obtained in 2000-2001 when the last surveys were undertaken, using a full range of survey techniques (particularly pitfall traps that are known to be superior to Elliott traps for catching most species of dunnarts). Researchers have estimated the total population of Kangaroo Island Dunnarts to be less than 500 individuals. Kangaroo Island Dunnarts are known from six trapping sites, but these should essentially be treated as one location because they would all be vulnerable to a potential single catastrophic event and may represent a single population. Wildfires are the greatest potential threat facing Kangaroo Island Dunnarts. Inappropriate fire management exacerbates the potential for an extensive, hotfire that could kill all Kangaroo Island Dunnarts. Another threat is Phytophthora cinnamomi, a water mold (Oomycete) that is destroying many heath-dependent species in the area; it has caused general changes in habitat structure that probably negatively affect the Kangaroo Island Dunnart. Introduced domestic cats may also affect Kangaroo Island Dunnarts, although their impact is not well understood. On the eastern end of Kangaroo Island,livestock grazing, weeds, and other fragmentation processes, such as land clearing for agriculture, have degraded preferred habitats. A recovery plan lists the following six actions as being required for sustainable management of the Kangaroo Island Dunnart: site protection and management of known populations, clarification of distribution and threatening processes, investigation of ecology and biology, increase in community awareness, establishment of a captive colony, and recovery planning. These actions are being pursued.

Bibliography. Aitken (1972), Archer (1981a), Baverstock et al. (1984), Blacket, Adams et al. (2001), Blacket, Cooper et al. (2006), Gates (2001a, 2001b), Herbert (1996), Kemper et al. (2011), Kitchener et al. (1984), Krajewski et al. (2012), Robinson (2008), Robinson & Armstrong (1999), Thomas (1888b), Van Dyck et al. (1994), van Weenen (2008), Woolley et al. (2007).

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)

Distribution. Kangaroo I, South Australia.