Genetic evidence in support of the recognition of the Kaputar Rock Skink, one of New South Wales’ most range-restricted vertebrate species

Abstract

The existence of the Kaputar Rock Skink, a morphologically distinct Egernia population restricted to the Nandewar Ranges in northern New South Wales, has been known for decades. However, no comprehensive description or diagnosis of the taxon has been published in the scientific literature, and its distinctiveness largely assumed. As part of a study investigating the genetic differentiation of faunal populations on the Nandewar Range, comparisons between the Kaputar Rock Skink and east Australian Egernia striolata-group species were undertaken. The results indicate that the Kaputar Rock Skink is a distinct genetic lineage, showing species-level divergence from other Egernia species. Field studies suggest the Kaputar Rock Skink is restricted to an extremely narrow band of rock habitat above 1000 m or more in elevation, and only occupies retreat and sheltering sites near cliff edges or in areas of extensive outcropping rock. It now appears to be a cool-adapted species constrained to high elevation habitat by niche conservatism. Field studies suggest the availability of suitable habitat on the summit areas of the Nandewar Ranges is highly limited, making it vulnerable to several potentially threatening processes, including anthropogenic climate change. The name Contundo roomi was erected for the Kaputar Rock Skink by Wells & Wellington in 1985, and we recommend Egernia roomi (Wells & Wellington, 1985) as the name for the Kaputar Rock Skink.

Australian Museum surveys of the vertebrate fauna of Coolah Tops National Park, NSW

“…However, genetic analysis of the E. striolata specimens sampled at Coolah Tops showed only slight differentiation from populations sampled further east and northeast on the Central and Northern Tablelands (Sadlier et al, 2019). Recently a population of 'striolata' group skinks from high elevation at Mt Kaputar was recognized as a distinct species (Sadlier et al, 2019). Detailed genetic analysis of the E. cunninghami samples from Coolah Tops is currently underway, but initial results show this population to be genetically differentiated from populations to the east on the Walcha basalts and Moonbi granite ranges.…”

“…Previously a lack of samples from Coolah Tops had meant no genetic study had been conducted assessing the degree of isolation of the Coolah Tops populations. However, genetic analysis of the E. striolata specimens sampled at Coolah Tops showed only slight differentiation from populations sampled further east and northeast on the Central and Northern Tablelands (Sadlier et al, 2019). Recently a population of 'striolata' group skinks from high elevation at Mt Kaputar was recognized as a distinct species (Sadlier et al, 2019).…”

Determining the geographic distribution and ecology of the Critically Endangered Kaputar rock skink (Egernia roomi)

“…The diagnosis purported a single morphological feature (enlarged paravertebral scales) that is not unique to this species, but is shared by all congeners within the Egernia striolata species-complex (Shea and Sadlier 1999). As such, the Kaputar rock skink was not formally recognised as distinct until a recent study led by the Australian Museum confirmed the Mt Kaputar populations as a valid taxon based on combined genetic and morphological evidence (Sadlier et al 2019). Apart from this re-description study, the species has received little research or conservation attention.…”

“…Such is the case for the Kaputar rock skink (Egernia roomi). The species was formally recognised as a separate species (Sadlier et al 2019) only a month and a half prior to when fire began on Mount Kaputar in October 2019; a fire that eventually burned over 40% of the national park before it was extinguished a month later (DPIE 2021). Known only from an extremely limited area and elevational band of rock habitat (Sadlier et al 2019), this species was immediately flagged as a conservation concern (Legge et al 2022a).…”

“…Prior to our study, the Kaputar rock skink was only known from three sites within MKNP above 1360 m in elevation, including the Mount Kaputar summit, Mt Dowe, and The Governor (Sadlier et al 2019). Given its limited distribution, it is believed to be New South Wales' most range-restricted vertebrate taxon (Sadlier et al 2019). However, most of the Nandewar Range remains unsurveyed for reptiles outside of areas that have walking tracks and are easily accessible (Sadlier et al 2019).…”