Tuesday 22 August 2023

Planigale kendricki & Planigale tealei: Two new species of Dasyurid Marsupial from the Pilbara Region of Western Australia.

Among Mammals, the most diverse groups tend to be those which feed on Insects. In Australia, about a quarter of all land Mammals belong to the Dasyuridae, which ate insectivorous and sometimes carnivorous Marsupials. The genus Planigale currently contains four species of Shrew-like insectivorous Marsupials, weighing between 3 and 17 g, which are found across most of the continent, with a fifth species on the island of New Guinea, although molecular studies have suggested that the genus probably contains more diversity than is reflected in this classification. Australia's indigenous Mammals have suffered greatly since the arrival of Europeans, with sharp declines in their numbers still being seen even in parts of the continent with few Human visitors, which makes having an accurate inventory of Australian Mammal species essential to conservation efforts.

The four currently described species of Planigale from Australia, Planigale gilesiPlanigale maculataPlanigale ingrami, and Planigale tenuirostris, are widely distributed in northern and eastern Australia. None of these species are considered to be threatened, but the two most widespread species, Planigale ingrami, and Planigale tenuirostris, have been shown to contain very high levels of genetic diversity, which may indicate that they are actually multiple species with much smaller ranges, and therefore potentially at conservation risk. 

The last major revision of the genus Planigale was carried out in 1976 by zoologist Michael Arche, but since that time genetic methods have become available, with several studies having suggested that there might be one or two undescribed species belonging to the genus present in the Pilbara Region of northerm Western Australia.

In a paper published in the journal Zootaxa on 14 August 2023, Linette Umbrello of the School of Biology and Environmental Science at the Queensland University of Technology, and Collections and Research at the Western Australian Museum, Norah Cooper, also of Collections and Research at the Western Australian Museum, Mark Adams of the Department of Biological Sciences at the University of Adelaide, and the Evolutionary Biology Unit at the South Australian Museum, Kenny Travouillon, again of Collections and Research at the Western Australian Museum, Andrew Baker, also of the School of Biology and Environmental Science at the Queensland University of Technology, and of the Biodiversity and Geosciences Program at Queensland Museum, Mike Westerman of the Department of Environment and Genetics at La Trobe University, and Ken Alpin, again of Collections and Research at the Western Australian Museum, and of the Australian Museum Research Institute at the Australian Museum, formally describe two new species of Planigale from the Pilbara Region.

The approximate distributions of the four currently recognised species of Australian Planigale with Pilbara distributions indicated with arrows. Umbrello et al. (2023).

The first new species described was originally identified as a candidate species in the first ever genetic study of the group, published 1995, in which a team led by Jodie Painter of La Trobe University used the mitochondrial cytichrome b gene to determine the relationships between different species within the genus Planigale. At the time. the candidate species, identified only as Planigale 1, was known from only a single specimen, which was one of only two specimens from Pilbara included in the study (the other specimen was also identified as a new species, Planigale 2, but was later found to belong to a separate genus), but subsequent genetic studies have consistently recovered this species as a separate clade.

Umbrello et al. formally name Planigale 1 as Planigale kendricki, in honour of Peter Kendrick, in recognition of his major contribution to the understanding of the vertebrate fauna of north-western Australia. Planigale kendricki is large for a species of Planigale, with a maximum recorded weight of 12.5 g and a maximum recorded length of 74 mm (excluding the tail). Females are smaller than the males, with a maximum recorded weight of 9.5 g and a maximum recorded length of 69 mm. It is more reddish than other species of the genus, with its back and flanks covered by a thick coat of orange-tan fur with patches of dark brown, while the hair of the underside is grey, changing to yellow or even brown at the tips.

Planigale kendricki. Note the rufous, orange-tan colouration of the fur and the orange eye ring.  Roy Teale in Umbrello et al. (2023).

Planigale kendricki is found across the Pilbara and the surrounding area of northern Western Australia, including the Cape range Peninsula, Ashburton and Gascoyne regions, with specimens reported from the Great Sandy Desert and Little Sandy Desert, Lake Auld, and Mandora near Eighty Mile Beach. It appears to favour areas with exposed bedrock, including sandy plains, scree slopes and rocky creek beds. 

Proposed distribution of Planigale kendricki inferred from specimens at the western Australian Museum (blue dots) that were examined during this study. the border of the Pilbara region is shown by the dashed line in inset A. Umbrello et al. (2023).

The second new species was first identified as a candidate species in a study led by Mark Blacket of La Trobe University and published in 2000, in which a much larger selection of Planigale specimens were examined, and a phylogeny for the genus developed using the 12S rrNA gene sequence. Blacket et al. identified this candidate species as Planigale Mt Tom Price, in reference to the area where it was discovered. This species was also recovered by subsequent genetic studies in 2009, 2016, and 2020, which looked at different gene sets.

Umbrello et al. formally name Planigale Mt Tom Price as Planigale tealei, in honour of Roy Teale, for his support for the work of the Western Australian Museum over many decades, and for collecting many of the specimens on which the description of the species is based. Planigale tealei is small for a species of Planigale, with a maximum male size of 6.1 g and 62.5 mm in length (excluding the tail), and a maximum female size of 4.7 g and 60 mm in length. Its back and sides are covered with a thick, greyish brown coat, paler on the flanks, and pale on the underside.

Planigale tealei (WAM M62896). Linette Umbrello in Umbrello et al. (2023).

Planigale tealei appears to be largely restricted to the Pilbara Region, with very few records outside of the area. It us usually encountered on cracked clay soils in areas with plenty of exposed rocky outcrops, preferring more clay-rich soils.

Proposed  distribution  of Planigale  tealei  inferred  from  specimens  (pink  triangles)  in  the western  Australian Museum that were examined during this study, including southern locality of Waldburg Station. the border of the Pilbara is shown by a dotted line in Inset A. Umbrello et al. (2023).

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