Australian scientists have uncovered that what was previously considered a single widespread species of Planigal is actually four distinct species, including a newly identified species that thrives exclusively on the rocky slopes of Kakadu National Park.
Revised distribution of the four Planigale species complex previously classified as Planigale ingrami. Image credit: Umbrello et al., doi: 10.1093/zoolinnean/zlag082.
Planigals, small marsupials primarily feeding on insects, are known for their flat skulls which allow them to fit into narrow crevices in their habitats.
These unique creatures inhabit various terrestrial environments across Australia and New Guinea, with nine species now recognized.
Among them, Planigale ingrami holds the title of the world’s smallest marsupial, weighing an average of just 4.2 g (as little as 2.6 g) and measuring 5.7 cm from head to body.
A recent study by researchers from the Western Australian Museum and Queensland University of Technology, led by Dr. Lynette Umbrello, utilized genetic analysis and museum specimens to reveal the complex Planigale ingrami species classification, introducing Planigale tea ray and unveiling two unclassified lineages.
The team analyzed DNA samples from over 220 individuals combined with detailed measurements of skull and body proportions, derived from collections in natural history museums across Australia.
“This study leveraged historical samples to identify species that might never be documented in contemporary settings,” Dr. Umbrello noted.
“We undertook thorough genetic sampling and morphological analysis of Planigal specimens from museum collections throughout Australia.
“Our data integration approach, termed integrative taxonomy, enabled us to identify species previously grouped under a single classification.”
The researchers delineated three distinct lineages among the studied samples, including Planigale ingrami.
“We re-listed Planigale subtilissima, previously thought to belong to: Planigale ingrami, as a separate species,” Dr. Umbrello remarked.
“Furthermore, the subspecies Planigale ingrami brunea was reassigned to its original classification.”
“We also discovered a completely new species: Planigale petrophila.
Planigale petrophila (commonly known as the Arnhem Plateau Planigal) is distinguished from its relatives by several characteristics.
While most Planigal species prefer lowland clay soils, this species is adapted to rocky cliff environments.
Significantly larger than its closest relatives, it boasts the longest tail recorded for any Planigal, surpassing its body length.
“Planigale petrophila is a medium-sized Planigal with a notably flat skull and an exceptionally long tail,” the scientists explained.
“It uniquely features the longest tail of any genus member (8.05-9.19cm), outstripping even the larger Planigale novaeguineae specimens (from New Guinea) that reach 8 cm.”
Currently, only three specimens of Planigale petrophila are known, all collected within a close range of 12 km in Kakadu National Park, with the latest one documented in 2004 — none have been observed since.
The researchers highlighted the concerning decline of native mammal populations in Kakadu, urging an immediate conservation assessment.
“Planigale petrophila is undoubtedly rare among Australian Planigals, with just three specimens identified and its known habitat limited to a small area of the sandstone plateau and rocky slopes in Kakadu National Park,” Dr. Umbrello stated.
The only other Planigal recorded in Kakadu National Park is Planigale maculata, which occupies lowlands and basins rather than sandstone plateaus.
“Planigale petrophila is distinctive for its notably longer tail compared to other Planigal species, and exhibits larger body-to-skull ratios than its genetically closest relatives.”
“Our findings suggest Planigale petrophila may be threatened,” added Dr. Andrew Baker from Queensland University of Technology and Queensland Museum.
“Given the limited geographical area where Planigale petrophila has been identified, along with the alarming declines observed in other mammal species in Northern Australia, we strongly recommend an urgent conservation assessment.”
“This species is known from only three specimens collected within 12 km and has not been encountered since 2004.”
“Accurate classification and taxonomy are vital for conservation efforts to ensure appropriate management strategies are implemented.”
“This information plays a crucial role in establishing the conservation status of this new mammal, especially considering the broader decline in Kakadu and other native species in Australia.”
The team’s results will be published in the Zoological Journal of the Linnean Society.
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Lynette S. Umbrello et al. 2026. Disentangling the Onagaplanigale (Dassuriidae: Planigale ingrami) Species Complex: Four Species Revealed Using Integrated Taxonomy. Zoological Journal of the Linnean Society 207 (2): zlag082; doi: 10.1093/zoolinnean/zlag082
Source: www.sci.news
