Planigale gilesi, Aitken, 1972

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 : 327-328

47.

Giles’s Planigale

Planigale gilesi

French: Planigale de Giles / German: Giles-Flachkopfbeutelmaus / Spanish: Planigalo de Giles

Other common names: Paucident Planigale

Taxonomy. Planigale gilesi Aitken, 1972 ,

Ann Creek Station (No. 3 bore) (28° 18’ S, 136° 29° 40” E), South Australia, Australia.

In 1928, E. Le G. Troughton erected the genus Planigale to accommodate three species of tiny, flatheaded dasyurids known from Australia. This species was named after E. Giles, who explored many of the Australian deserts. When P. gilesi was described in 1972, it was known from only a dozen specimens; however, trapping surveys since then have greatly extended its known distribution. In 1976, M. Archer conducted a major revision of the genus Planigale . He recognized three morphologically based species groups: the P. maculata group, containing P. maculata and P. novaeguineae , the P. ingrami group, containing P. ingrami and P. tenuirostris , which were very similar morphologically; and a monotypic group containing P. giles, a species morphologically distinct from other planigales by possessing only two upper and lower premolar teeth. Various genetic studies have been conducted on the genus Planigale since the early 1980s. The genus was placed in its own subfamily because it shared no morphological features allying it indisputably with other dasyurids. Nevertheless, 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 genetic (allozyme) and serological evidence. DNA sequencing has since corroborated the close genetic relationship of these four genera. Monophyly of Planigale has been well established genetically. Using mtDNA, one study resolved P. giles: as clearly divergent, positioned as a poorly resolved sister to a clade containing the remainder ofits congeners. Monotypic.

Distribution. Australia, from Boulia, SW Queensland, S as far as extreme NW Victoria, along the Murray River, and from the Stuart Highway in extreme S Northern Territory and C South Australia to near Moree, N New South Wales.

Descriptive notes. Head-body 6-8 cm (males) and 6-7 cm (females), tail 5.5-7 cm (males) and 5.5-6.5 cm (females); weight 9-5-16 g (males) and 5-9 g (females). There is mild sexual dimorphism forsize. Giles’s Planigale is brindled cinnamon-gray above and olive-buff below. Like other planigales,it has a flattened, triangular head, beady eyes, and pointed nose; ears are small, rounded, and lie against head. There are only two upper and two lower premolar teeth in Giles’s Planigales compared with three in other planigales. Legs are short compared with body length, ensuring that it moves low to the ground. Hindfeet are moved in an outwardly extended arc, not in line under the body. Running is a scurrying motion, often accentuated with short leaps and bounds. In seasons with abundant prey, tail of Giles’s Planigale becomes swollen and carrot-shaped with stored fat; when conditions are poor, tail is thin and bony. Compared with congeners, Giles’s Planigale is, on average, larger than the Longtailed Planigale ( P. ingrami ) and the Narrow-nosed Planigale ( P. tenuirostris ). One study found that average head-body length of Giles’s Planigale was 68 mm compared with 45-64 mm for the Long-tailed Planigale and the Narrow-nosed Planigale, average hindfoot was 10-6 mm compared with 7-4-9 mm, average lower molar tooth row was 3-6 mm compared with 2:7-3-1 mm, and mean body weight was 7-7 g compared with 4-6 g and 5-5 g. Giles’s Planigale has black claws, the Narrow-nosed Planigale has pale or caramel claws, and the Long-tailed Planigale has claws that are mostly pale, being gray-brown only at base.

Habitat. Deep, cracking clay soils on floodplains of creeks and rivers, grassy plains away from creeks, and clay interdune areas in sandhill country. Presence of soil cracks is apparently an important habitat requirement of Giles’s Planigale, providing essential shelter from both heat and cold. Giles’s Planigale has strong affinities for stony plains, flood outs, clay plains, and ephemeral swamps. Vegetative structure in these areas includes shrublands and tussock grasslands, but it has also been recorded in low shrublands. Giles’s Planigale (like the Long-tailed Planigale) prefers areas featuring dwarf chenopod shrubs, herbs, and grasses with taller lignum (Muehlenbeckiaflorulenta, Polygonaceae ) or Queensland bluebush ( Chenopodium auricomum, Chenopodioideae); shrubs characterize the more regularly flooded areas that support Giles’s Planigales, often featuring an open overstory of coolibah ( Eucalyptus coolabah, Myrtaceae ) woodland in the most regularly flooded areas. Giles’s Planigale often co-occurs with Narrownosed Planigales, particularly in drier gibber plain habitats where it appears to favor patches that are subject to temporary flooding from local runoff and contain deeper cracking clay soils.

Food and Feeding. Giles’s Planigale actively hunts beetles, locusts, spiders, centipedes, and other arthropods;it will occasionally eat small lizards and mammals. It swiftly and fearlessly attacks large prey, biting, hanging on, and chewing. Smaller prey items are quickly and repeatedly crunched. In one recent study of diet of Giles’s Planigale in western New South Wales, spiders ( Araneae ) were the main prey, comprising 32% of the volume of invertebrates consumed; Hymenoptera (mainly ants), Orthoptera (mainly crickets), and slaters (Isopoda) were also heavily preyed on.

Breeding. Breeding in Giles’s Planigale occurs from mid-July to late January, with 1-2 litters/female in a season. Estrous cycle is 21 days. Mating can last more than two hours, and gestation is 16 days. The rear-opening pouch of Giles’s Planigale encloses twelve teats. Young are independent at ¢.65 days and weigh c.4 g. The usuallitter size is 6-8 young. A captive breeding study of individuals from Fowler’s Gap, western New South Wales, indicated there was a trend for males to grow faster than females. Eye opening and end of weaning of Giles’s Planigale were two important developmental stages, associated with changes promoting reduced growth rate. Changes in body condition ofjuveniles indicated that mothers initiated weaning.

Activity patterns. In soil cracks, Giles’s Planigale clambers with speed up, down, and across vertical walls ofits shelter. It is agile, with broad, dexterous feet and very flexible ankle joints. Above ground,it climbseasily in grass and shrubs or slithers through litter. Generally, Giles’s Planigale spends considerable time above ground, especially in the crepuscular period. During summer and winter,its daily activity has a broad bimodal pattern, with most activity occurring in the three hours after sunset and the hour before sunrise. On average, Giles’s Planigales are active for ¢.5 hours/day. During winter, they may be found basking in the sun for warmth or become torpid for short periods to conserve energy. Indeed, when individuals are active at air temperatures below normal body temperature of ¢.34°C, their metabolic rates increase to counter the cold. At air temperatures of 14-20°C, metabolic increase may be up to tenfold. One study in Kinchega National Park, western New South Wales, investigated importance of energy-conserving strategies for free-ranging Giles’s Planigales in arid Australia. Torpor use and basking behavior were monitored using internal temperature-sensitive transmitters. Results showed that torpor was used every day; maximum torpor duration was 18-2 hours and minimum body temperature was 10-5°C. Basking behavior was observed during rewarming from torpor. Use of torpor and basking in Giles’s Planigale likely reduces energy requirements, thus helping it to survive in a harsh and unpredictable environment.

Movements, Home range and Social organization. Individual Giles’s Planigales (excluding lactating females with dependent young in nests) evidently have shifting home ranges; some travel more than 1 km in a few days. One recent study radio-tracked three Giles’s Planigales in Kinchega National Park and found that individuals rested in an extensive system of cracks formed in dry clay soil under lignum bushes. Resting sites were located in soil cracks with narrow openings. Giles’s Planigales rested at deep sites, based on weak transmitter signals, which were often reduced to less than 3 m. Nesting ranges were 0-07-0-15 ha, and maximum distances between any locations recorded was 78-126 m. Resting sites were reused 2—4 times, up to nine days apart; one individual alternated between two sites separated by 16 m for six days. Vocalizations are loud and include a “chh, chh” or sharp “ca, ca,” in association with aggressive or defensive behavior such as chasing another individual or defending a refuge. A highpitched twittering, similar to that of a small bird, is made by Giles’s Planigales when frightened. In the breeding season, females in estrus and males expressing interest in them call to each other with high-pitched clicking sounds. Densities of Giles’s Planigale are generally low and fluctuate notably from season to season and year to year. It is possible that fewer than 20% of individuals survive more than two years in the wild. In captivity, however, some individuals have attained the age offive years.

Status and Conservation. Classified as Least Concern on The IUCN Red List. Giles’s Planigale has a wide distribution and presumably a large overall population; it does not appearto face any major conservation threats. Throughout its distribution, Giles’s Planigales are often encountered in fauna surveys, regardless of whether these are undertaken in national parks or areas grazed by domestic sheep and cattle.

Bibliography. Aitken (1972), Archer (1976a, 1982c), Baverstock et al. (1982), Blacket, Adams et al. (2000), Blacket, Kemper & Brandle (2008), Ellis, van Weenen & Pennay (2008), Krajewski, Blacket et al. (1997), Krajewski, Young et al. (1997), Painter et al. (1995), Read (1984a, 1984b, 1987a, 1987b, 1988, 1989, 2008a), Troughton (1928), Warneke & Geiser (2009), Warneke et al. (2012).

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. Australia, from Boulia, SW Queensland, S as far as extreme NW Victoria, along the Murray River, and from the Stuart Highway in extreme S Northern Territory and C South Australia to near Moree, N New South Wales.