Sminthopsis griseoventer, 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 : 341-342

65.

Grey-bellied Dunnart

Sminthopsis griseoventer

French: Dunnart a ventre gris / German: Graubauchige Schmalfu 3beutelmaus / Spanish: Raton marsupial de vientre gris

Other common names: Boullanger Island Dunnart (boullangerensis)

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

Bindoon , 31° 18° S, 116° 01’ E, Western Australia, Australia .

Phylogenetic relationships among the 28 species comprising the dunnarts (and relatives) within Sminthopsinae have been the subject of considerable morphological and molecular attention. Importantly, recent genetic phylogenies fail to support monophyly of the genus Sminthopsis with respect to Antechinomys and Ningaui . There are three deeply divergent clades of Sminthopsis . In the first, S. longicaudata is sister to A. laniger (a result corroborated by morphology). The second clade is composed of the traditional morphologically based Macroura Group: five Sminthopsis comprise a strongly supported clade that includes S. crassicaudata , S. binds, S. macroura , S. douglasi , and S. virginiae . This clade of five dunnarts is positioned as a poorly supported sister to the three species of Ningaui (N. ridei , N. timealeyi , and N. yvonneae). The combined clade of five Sminthopsis and three Ningaui is itself a poorly supported sister to a well-supported clade containing the remaining species of Sminthopsis (13 species in the Murina Group). In 1984, D. J. Kitchener and colleagues (in view of concurrent genetic research being conducted by P. R. Baverstock and colleagues) redefined S. murina (sensu, M. Archer in 1981) and introduced four new species (S. dolichura , S. gilbert, S. griseoventer , and S. aitkeni ) on morphological criteria. The latest genetic work on the group (2012) supports these taxa. The large dunnart clade comprising the Murina Group contains a well-supported sister pairing of S. griseoventer with S. aitkeni , but it does not include them in a monophyletic group with Kitchener’s other murina-group species. Previous research (2011) had investigated relationships between S. griseoventer and its sister taxon, S. aitkeni . Phylogenetic analyses of mitochondrial (hypervariable control-region) sequence data revealed that S. aitken: haplotypes were nested with S. griseoventer from Eyre Peninsula; they differed by just 0-3%. In comparison, allozyme genetic analyses revealed fixed allelic differences at three loci between S. aitkeni and S. griseoventer . Yet, the pattern of moderate allozyme divergence and very low mtDNA divergence contrasted with the pattern of divergence within S. griseoventer itself; populations from Western Australia and Eyre Peninsula had minimal allozyme divergence butrelatively higher mtDNA divergence (1-5-2:8%). In synthesis, analyses suggested absence of recent gene flow between S. aitkeni and S. griseoventer , but apparently there has been no long-term isolation (and indeed there may have been introgression of the mtDNA genome between the two by interbreeding). In 1999, M. S. Crowther and colleagues defined a new subspecies from the S. murina complex, S. griseoventer boullangerensis, from Boullanger Island off the Western Australia coast. The subspecies was considered previously to be identical to S. g. griseoventer , a form common on the mainland of south-western Western Australia, but the new work showed them to differ with fixed differences at three of 18 genetic allozymes screened. The Boullanger Island form also differed from the nominate griseoventer in having a relatively longer tail and no entoconid cusps on the second and third molar teeth. Researchers did not accord it full species status because it did not differ appreciably in mtDNA control region sequences from the nominate griseoventer , but they pointed out that the proposed subspecific ranking was conservative given the range of differences between forms. Nevertheless, several years later another research group, rerunning some boullangerensis samples with fresh tissue, concluded that neither molecular nor morphological data from the earlier work supported differentiation at taxonomic or evolutionarily significant levels. They recommended that boullangerensis be regarded as a junior synonym of S. g. griseoventer and deleted from lists of threatened Australian taxa, although conceding that the island population should be managed separately from those found on the mainland. The most recent assessment of the species retains both subspecies of S. griseoventer as originally proposed; thus, that taxonomy is honoured here, with a cautionary note that further work is urgently required to resolve the taxonomy of this species. Two subspecies recognized.

Subspecies and Distribution.

S.g.griseoventerKitchener,Stoddart&Henry,1984—SAustralia,SWWesternAustraliaandanoutlyingpopulationintheEyrePeninsula,SSouthAustralia.

S. g. boullangerensis Crowther, Dickman & Lynam, 1999 — Boullanger I, Western Australia.

Descriptive notes. Head-body 6-:8.9-4 cm (males) and 6-5-8:8 cm (females), tail 6:6.9-8 cm (males) and 6.5-9.5 cm (females); weight 15-24 g (males) and 14-20 g (females). There is subtle sexual dimorphism for size. Fur of the Grey-bellied Dunnart is pale fawn above (mottled by dark brown tipping of hairs) with cream-colored fur below; dorsal and ventral hairs are blue-gray at bases. Tail is white with a thin, dorsal line of dark brown hairs; paws are white. Hind margins of ears are notched. Pads on palms and soles are finely and evenly granulated, without enlarged granules, smooth areas, or hairs.

Habitat. Wide variety of habitats from open woodland of Eucalyptus (Myrtaceae) and Banksia (Proteaceae) to low mallee, dense heath, and seasonal swampland. The densest populations of Grey-bellied Dunnarts occur in coastal heath on sandy soils, usually at least ten years afterfire. Kitchener and colleagues provided detailed descriptions of habitats of Gilbert's Dunnarts where they have a broad and continuous distribution.

Food and Feeding. Invertebrates form the bulk of the diet of Grey-bellied Dunnarts, but young House Mice ( Mus musculus), lizards, and soft fruits are also eaten occasionally. Grey-bellied Dunnarts search for prey under leaflitter, locating it using all their senses, but especially smell. Prey larger than 3 cm long is preferred and is held in forepaws before being killed. Smaller prey items are grabbed directly with jaws.

Breeding. Breeding of the Grey-bellied Dunnart is restricted to winter and spring. In the population on Boullanger Island, both sexes mate promiscuously in July; females carry litters of up to eight young in August. Pouch life lasts 4-5 weeks. Young are thereafter deposited in a leaf-lined nest just under the surface of the soil; they first emerge onto the forest floor in late October at c.10 weeks of age. Young females remain near their area of birth, but males disperse up to several hundred meters within two months of weaning. Survival of both sexes up to this time is less than 50%. Females give birth to only one litter a year and rarely produce young in consecutive seasons. Males and females become sexually mature at c.1 year of age and live to 2-5 years at the most.

Activity patterns. The Grey-bellied Dunnart is nocturnal, with most activity occurring in early and late parts of the night.

Movements, Home range and Social organization. Density in the Grey-bellied Dunnart ranges from 3 ind/ha in spring to a peak of 9 ind/ha in summer, after young become independent. Life history events appear to be similar in adjacent mainland populations but are delayed by up to two months.

Status and Conservation. Classified as Least Concern on The IUCN Red List. The subspecies boullangerensis is listed as vulnerable in Australia. The Grey-bellied Dunnart has a wide distribution, presumably has a large overall population, occurs in a number of protected areas, and does not face any major conservation threats. In 2011, research indicated that distribution of present-day Grey-bellied Dunnarts in South Australia is Eyre Peninsula, where it is broadly sympatric with the Little Long-tailed Dunnart (S. dolichura ). Close sympatry occurs at four protected areas: Pinkawillinie, Munyaroo, and Bascombe Well conservation parks and Hambidge Wilderness Protection Area. Two localities for Grey-bellied Dunnarts (Heggaton and Munyaroo conservation parks) were recorded solely on the basis of DNA identifications of released (non-vouchered) animals. Subfossil records provide strong evidence that the distribution of the Grey-bellied Dunnart once included at least what is now the lower Yorke and Eyre Peninsula and near the South Australia—Western Australia border. The Greybellied Dunnart appears to be common in its limited habitat. Locally,it is threatened by continued habitat clearing and fragmentation. Domestic and feral cats (Felis catus) negatively affect Grey-bellied Dunnarts, although populations have been able to withstand this predation. Further research is needed to determine taxonomic status of populations on Boullanger Island; this research should include seeking definitive evidence of whether boullangerensis occurs on the mainland in sympatry with the nominate griseoventer , and an analysis of allozymes and DNA from northern populations of Grey-bellied Dunnarts.

Bibliography. Archer (1981a), Baverstock et al. (1984), Blacket, Adams et al. (2001), Blacket, Cooper et al. (2006), Crowther et al. (1999), Dickman (1988a, 2008c), Groves (2005a), Kemper et al. (2011), Kitchener et al. (1984), Krajewski et al. (2012), McKenzie & Kemper (2008), Start et al. (2006), Thomas (1888b).

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.g.griseoventerKitchener,Stoddart&Henry,1984—SAustralia,SWWesternAustraliaandanoutlyingpopulationintheEyrePeninsula,SSouthAustralia. S. g. boullangerensis Crowther, Dickman & Lynam, 1999 — Boullanger I, Western Australia.