Delma impar 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Reptilia Squamata Pygopodidae

Scientific Name: Delma impar (Fischer, 1882)
Common Name(s):
English Striped Legless Lizard, Many-lined Delma
Pseudodelma impar Fischer, 1882
Identification information: This species has a distinctive broad olive brown linear vertebral stripe, with narrow, dark and pale lateral lines which tend to break into oblique bars or rows of spots on the tail (Wilson and Swan 2013).

Assessment Information [top]

Red List Category & Criteria: Endangered B2ab(iii) ver 3.1
Year Published: 2017
Date Assessed: 2017-06-13
Assessor(s): Clemann, N., Melville, J., Michael, D., Robertson, P., Hutchinson, M. & Gillespie, G.
Reviewer(s): Bowles, P.
Contributor(s): Harrison, N.
Facilitator/Compiler(s): Chanson, J.S.
Listed as Endangered because the species' area of occupancy, inferred from its survival at 45 individual localities, is likely to be considerably less than 200 km2, the species occurs as a severely fragmented population, and there is an ongoing decline in the extent and quality of its habitat driven mainly by urban development and agricultural intensification.
Previously published Red List assessments:

Geographic Range [top]

Range Description:Delma impar occurs in the south east corner of Australia where it is found from southeastern South Australia to the Australian Capital Territory and the surrounding area in New South Wales, up to the Hunter Valley (D. Michael pers. comm. 2017). The species' distribution in Victoria, the largest part of its range, consists of small and isolated subpopulations in restricted areas of remnant habitat, the majority of these on the basalt plains north and west of Melbourne (P. Robertson pers. comm. 2017).
Countries occurrence:
Australia (Australian Capital Territory, New South Wales, South Australia, Victoria)
Additional data:
Estimated area of occupancy (AOO) - km2:180
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:This species is cryptic and rare, and significant declines have been reported (Banks 1992, Dorrough and Ash 1999). There has been an "obvious decline" in areas of Victoria to the north, west and south of Melbourne due to land clearance, much of which has occurred in the past 15 years (N. Clemann and P. Robertson pers. comm. 2017). The species is known to have disappeared from many historical localities (Smith and Robertson 1999): of 125 known localities, the species was estimated to survive at as few as 45 by Hadden (1995). The majority of the known sites supporting surviving subpopulations are between one and 50 ha (range 0.25-400 - O'Shea 2005) in size and many are isolated (Hadden 1995).

This species exhibits low vagility and appears unable to traverse areas between remnant grassland, and patterns of genetic variation suggest a recent loss of genetic connectivity between at least some subpopulations (O'Shea 2005). Dorrough and Ash (1999) calculated a subpopulation-level dispersal rate below 12 m per year, with subpopulations migrating to habitat patches no more than 2 km away from historic sites over the course of 150 years. While individual isolates may be viable in the absence of disturbance, population viability analysis suggests that many are small enough following historical habitat fragmentation for their persistence to be threatened by stochastic factors, or by individual catastrophic events such as fire (O'Shea 2005 and refs therein), and the majority are subject to ongoing pressure from anthropogenic threats. As such the population is considered to be severely fragmented.
Current Population Trend:Decreasing
Additional data:
Population severely fragmented:Yes

Habitat and Ecology [top]

Habitat and Ecology:This fossorial, insectivorous species is restricted to temperate grassy plains and grassy woodlands where animals shelter beneath loose rocks, grass tussocks and in soil cracks (Dorrough and Ash 1999, Wilson and Swan 2013). The species has been found to favour areas of grassland with high levels of structural complexity (Howland et al. 2016). Animals can persist in exotic vegetation types if the habitat structure is suitable (Howland et al. 2016 and refs therein), but is most commonly associated with native temperate grasslands possibly as a consequence of lower levels of disturbance in these remnant habitats (Howland et al. 2016). Estimates of growth rates and expected life history patterns suggest that this species, which has a maximum lifespan of at least 10 years and possibly "significantly longer" (Banks et al. 1999 suggests a possible maximum figure of 20 years), and reaches sexual maturity at 2-4 years of age (Smith and Robertson 1999).
Continuing decline in area, extent and/or quality of habitat:Yes
Generation Length (years):7

Use and Trade [top]

Use and Trade: There is no known use of or trade in this species.

Threats [top]

Major Threat(s): The species was once widespread in the temperate grasslands of southeastern Australia, but approximately 99.5% of natural temperate grasslands in this area have been lost through land clearance or agricultural intensification over the past 200 years (Kirkpatrick et al. 1995). Native grassland is now classified as an endangered ecological community (Department of the Environment and Heritage 2003). Much of the remaining habitat of this species on the fertile plains of southern Victoria continues to be dramatically reduced due to agricultural and urban developments (Wilson and Swan 2013). Pasture improvement and overgrazing are threats to this species (Howland et al. 2016), including increased grazing pressure from expanding populations of the native Eastern Grey Kangaroo (Macropus giganteus) (Howland et al. 2014, 2016). Intensification of grazing pressure is likely to be detrimental to this species, as while moderate grazing pressure can promote structural complexity this is lost in heavily-grazed areas (Howland et al. 2016). A little more than 50% of the known localities are under some form of grazing management, and 33% are not managed at all (O'Shea 2005). Inappropriate fire regimes and invasion of native grasses are also threats, and it is suspected that predation from feral cats and foxes also has a negative effect on this species (Department of Environment 2016) in particular in the outskirts of Melbourne, although further research is required to confirm this (Smith and Robertson 1999).

Conservation Actions [top]

Conservation Actions: Delma impar is listed as Endangered in Victoria and South Australia, and Vulnerable by the Commonwealth, New South Wales and the Australian Capital Territory (Macdonald 2015, DSE 2013). Across this species' range it is only known to occur in three conservation reserves (Smith and Robertson 2010). Management of the habitat of this species should exclude high intensity grazing, but ensure enough disturbance to create complex grass structures (Howland et al. 2014, 2016). Assisted dispersal may be necessary for the conservation of this species (Dorrough and Ash 1999). There was a National Recovery plan for 1999 to 2003 and a subsequent update, this is going to be downgraded to a Conservation Advice which identifies critical populations and habitats for protection (Department of Environment 2016, Department of Environment and Energy 1999). There are four genetically distinct management clusters that require individualised conservation measures. They should be considered separate Evolutionary Significant Units.

Citation: Clemann, N., Melville, J., Michael, D., Robertson, P., Hutchinson, M. & Gillespie, G. 2017. Delma impar. The IUCN Red List of Threatened Species 2017: e.T6315A101742864. . Downloaded on 23 February 2018.
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