Planigale ingrami (Thomas, 1906)

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 : 328

48.

Long-tailed Planigale

Planigale ingrami

French: Planigale d'Ingram / German: Langschwanz-Flachkopfbeutelmaus / Spanish: Planigalo de cola larga

Other common names: Blacksoil Planigale, Ingram’s Planigale

Taxonomy. Phascogale ingrami Thomas, 1906,

Alexandria, Northern Territory, Australia.

E. Le G. Troughton erected the genus Planigale in 1928 to accommodate three species of small, flatheaded dasyurids known from Australia at that time. Much later, in 1976, M. Archer conducted a comprehensive revision of the genus Planigale . He recognized three species groups based on morphology: the P. maculata group, containing P. maculata and P. novaeguineae , the P. ingrami group, containing P. ingrami and P. tenwirostris, both extremely similar morphologically; and a monotypic group containing FP. gilesi , which is morphologically distinct from other planigales in possessing only two upper and lower premolar teeth. Various genetic studies have been conducted on the genus Planigale since the early 1980s. Initially, the genus was placed in its own subfamily, because it shared no morphological features allying it clearly with other dasyurids. Planigale was later incorporated in a distinct tribe, Planigalini, within the subfamily Sminthopsinae , along with three other dasyurid genera ( Sminthopsis , Antechinomys , and Ningaui ) based on genetics and serology. More recent DNA sequencing has corroborated the close genetic relationship of these four genera. Monophyly of Planigale has been well established genetically, which corroborates morphological uniqueness of the group. Using mtDNA, one study resolved P. ingrami as clearly monophyletic and positioned it as a poorly resolved sister to a clade containing P. maculata and P. tenwirostris. Interestingly, P. ingrami and P. tenuirostris in South Australia are broadly sympatric with P. gilesi but not with each other. There appears to be ecological habitat separation between all three species, with P. ingrami being the most restricted in distribution and habitat requirements. Three forms of P. ingram: have been recognized in the past but are no longer formally considered subspecies: Planigale ingrami form brunnea from the Richmond area; P. ingrami form ingrami found from Northern Territory to Townsville; P. ingrami form subtilissima found in Kimberley. It is possible that P. ingrami may also be genetically heterogeneous across this part ofits distribution or these forms may represent a south-east to a north-west cline. Monotypic.

Distribution. Mainly across N Australia, in NE Western Australia, Northern Territory, and Queensland, also in NE South Australia.

Descriptive notes. Head—body 5.7-1 cm (males) and 4.9-6.4 cm (females), tail 5-3— 6-8 cm (males) and 5.1-6.5 cm (females); weight 2:8-6-6 g (males) and 2:6-5-8 g (females). There is mild sexual dimorphism for size. The Long-tailed Planigale is the world’s smallest marsupial and one of the smallest mammals. Extremely flattened, wedge-shaped head and laterally inclined hindlimbs allow it to squeeze through very small spaces. Long-tailed Planigales have a permanently thin tail, usually slightly longer than head-body length (although proportionately shorter with increasing body size). It has three upper and lower premolar teeth.

Habitat. Narrow crevices in cracking clays of black-soil plains. These plains, which support tussock grasslands or sparse woodlands, are found throughout the drier interior of tropical northern Australia and occur as floodplains associated with major river systems nearer the coast. Surveys incorporating pitfall traps have shown Longtailed Planigales to be the most frequently encountered small mammalin its favored habitat. One study focusing on South Australian populations found that the Longtailed Planigale is restricted to the far north-east of the state, having most affinity with plains and flooded areas. In South Australia, vegetation communities in which Long-tailed Planigale has been recorded are typical of arid floodplain environments: dwarf chenopod shrubs, herbs, and grasses with taller lignum ( Muehlenbeckia florulenta, Polygonaceae ) or Queensland bluebush ( Chenopodium auricomum, Chenopodioideae). Shrubs characterize the more regularly flooded areas, and these support an open overstory of coolibah ( Eucalyptus coolabahs, Myrtaceae ) woodland in the most regularly flooded areas.

Food and Feeding. Despite its tiny size, the Long-tailed Planigale is a ferocious nocturnal predator, seeking prey through soil cracks and hunting on the surface. Large centipedes, often several times the length of the Long-tailed Planigale, are a favorite prey item. Any other creature small enough to be subdued is also viciously attacked, including spiders, grasshoppers, other insects and their larvae, small lizards, and even young mammals.

Breeding. Female Long-tailed Planigales have a well-developed, rear-opening pouch with 8-12 teats and have litters of 4-8 young. Pouch morphology of Long-tailed Planigales from Kimberley, with nipples located in two anterior pockets, is unique among carnivorous marsupials. Females with pouch young have been seen mostly in September-December, although births can occur throughout the year. Young become detached from teats at c.6 weeks old and are left in a grassy nest underlitter or within tussock grass clumps while the mother forages. Independent, immature Long-tailed Planigales generally appear in the population in December—April. In a recent study on reproduction in the Long-tailed Planigale based on individuals extracted from stomachs of feral cats shot in north-western Queensland, the extended breeding season commenced in August and most likely ended in December. Evidently, males and females live to breed in more than one season. Females examined had twelve nipples in the pouch. Pouch morphology was noted to differ from that of other species of planigales (and may be a useful diagnostic if pouch condition is closely monitored in field-captured specimens).

Activity patterns. Although mostly nocturnal, Long-tailed Planigales may also be active in the early morning, particularly after cold nights. They may become completely torpid under very cold conditions.

Movements, Home range and Social organization. There is no information available for this species.

Status and Conservation. Classified as Least Concern on The IUCN Red List. The Longtailed Planigale was originally known only from northern Australia. Many (genetically confirmed) specimens have since been collected farther south into South Australia, and the distribution of the Long-tailed Planigale now appears to be almost as extensive as that of the Common Planigale ( P. maculata ). Habitat of the Long-tailed Planigale in the south-eastern part of its distribution has been substantially impacted by conversion of native grasslands and woodlands to agriculture. The Long-tailed Planigale appears to persist under the dominant pastoral land use throughout the remainder ofits distribution, although densities notably decline in areas subjected to heavy grazing pressure.

Bibliography. Archer (1976a, 1982c), Baverstock et al. (1982), Blacket, Adams et al. (2000), Blacket, Kemper & Brandle (2008), Burnett (2008b), Fisher (2008), Krajewski, Blacket et al. (1997), Krajewski, Young et al. (1997), Painter et al. (1995), Thomas (1906), Troughton (1928), Woolley & Elliott (2013).

Figures

On following pages: 41. Short-furred Dasyure (Murexia longicaudata); 42. Broad-striped Dasyure (Murexia rothschildi); 43. Long-nosed Dasyure (Murexia naso); 44. Red-tailed Phascogale (Phascogale calura); 45. Northern Brush-tailed Phascogale (Phascogale pirata); 46. Common Brush-tailed Phascogale (Phascogale tapoatafa); 47. Giles's Planigale (Planigale giles); 48. Long-tailed Planigale (Planigale ingrami); 49. Common Planigale (Planigale maculata); 50. Papuan Planigale (Planigale novaeguineae); 51. Narrow-nosed Planigale (Planigale tenuirostris); 52. Wongai Ningaui (Ningauiride); 53. Pilbara Ningaui (Ningaui timealeyi); 54. Southern Ningaui (Ningaui yvonneae); 55. Kultarr (Antechinomys laniger).

Distribution. Mainly across N Australia, in NE Western Australia, Northern Territory, and Queensland, also in NE South Australia.