A lineage from the northeast of Gran Canaria has been described as the distinct species Chalcides bistriatus on morphological grounds (Pasteur et al. 1988). While this arrangement has a genetic basis the same lines of evidence indicate that the divergence between the two is both shallow and incomplete, suggesting both a young divergence and a lack of reproductive isolation (Speybroeck et al. 2020). On this basis Speybroeck et al. (2020) concur with Mayer and Tiedemann (1991) that C. bistriatus is best considered conspecific with C. sexlineatus.

This species is endemic to Europe, where it is restricted to Gran Canaria in the Canary Islands. It is assessed as Endangered both globally and for the EU 27 Member States because, although it remains common in uninvaded areas of Gran Canaria, the expansion of the invasive California Kingsnake has resulted in rapid declines, inferred to be at a rate greater than 50% in the 10 years since 2014. This decline is ongoing and the causes have not ceased, and will not be reversible unless the invasive snake can be controlled. In addition the species has an extent of occurrence of approximately 1,500 km² and an area of occupancy as low as or lower than 300 km², it occurs in fewer than five locations defined by the widespread threat from the snake, and it is undergoing a continuing decline in the quality of its habitat, the number of mature individuals, and the number of locations.

This species is endemic to the island of Gran Canaria and the adjacent small islet of Gando (Roque de Gando) in the Canary Islands, Spain. The species is found from sea level up to elevations approaching 1,950 m asl.

The species was introduced to La Palma over 60 years ago, but an established population, at the time restricted to an area of around 4 ha dominated by banana plantations, was first reported in 2010 (Medina 2010).

The species is abundant, but easily overlooked, over most of Gran Canaria. Using targeted active searches of suitable microhabitat between May and September 2018 (a total sampling effort of 206.7 hrs), Piquet and López-Darias (2021) found a total of 640 individuals in snake-free parts of Gran Canaria, but only 110 in sites where the invasive California Kingsnake (Lampropeltis californiae) has established. The vast majority (85.3%) of lizard detections were in uninvaded sites (Piquet and López-Darias 2021). 

The species was found to be significantly less abundant (by as much as 80%) in invaded than uninvaded areas, with the strongest difference found in the southern zone where the California Kingsnake has most recently become established (since 2015). Although the snake was introduced more than 20 years ago, established populations have only been confirmed since 2007, and since 2015 in the island's South zone, suggesting that the endemic lizard has declined in most invaded areas over a period of no more than 6–14 years (Piquet and López-Darias 2021). As the snake is now present over more than half of Gran Canaria, and has presumably continued to expand its range since the 2021 work was completed, the species is likely to have declined by more than 50% over the past 10 years (M.A. Carretero pers. comm. 2024).

As the species is cryptic, it is unclear whether the population is fragmented even in invaded areas (M.A. Carretero pers. comm. 2024) but as a significant minority of the range remains uninvaded it is unlikely that the population as a whole is presently severely fragmented.

The species is found in a wide variety of habitats including humid meadows and valleys, arid gullies and sandy areas, woodland and plantations (although the species is rarer in these habitats), cultivated land, especially stony areas or sites with stone walls. Two ecologically divergent morphs are recognised, corresponding to the northern (mesic) and southern (xeric) halves of the island (Suárez et al. 2014). Evidence that gene flow is almost entirely north to south suggests that animals from the south may have little ability to tolerate habitats in the north of the island (Suárez et al. 2014). The females give birth to between two and seven fully formed young.

The California Kingsnake was introduced to Gran Canaria in 1998 (Cabrera-Pérez et al. 2012), and has now become established in areas of the north, east and south zones of the island (Piquet and López-Darias 2021), occurring across about 50% of the island by 2021. The snake is known to prey on the Gran Canaria Skink (Monzón-Argüello et al. 2015), and the skink is described - along with the Gran Canaria Giant Lizard - as the snake's preferred prey by Piquet and López-Darias (2021). This predation is presumably the mechanism driving declines.

There is some collection of this species for the pet trade, but not at a level to constitute a threat to the species. There is also predation of the species by cats, but this is also unlikely to be a significant threat.

This species is collected for the pet trade in small numbers.

This species is protected by national legislation and it occurs in a number of protected areas on Gran Canaria.

The species is listed on Annex IV (animal and plant species of community interest in need of strict protection) of the EU Habitats Directive (Checklist for Annex I habitat types and Annex II, IV and V species - 24/05/2023). In addition, the species is listed on Appendix II (strictly protected fauna species) of the Convention on the Conservation of European Wildlife and Natural Habitats (Bern Convention).

Piquet and López-Darias (2021) report that communicating their findings regarding the impacts of kingsnakes on all three endemic lizards with local authorities has resulted in increased funding for efforts at snake control and exclusion, and the development of a Strategic Control Plan to Fight against the California Kingsnake 2019–2022 which aims to increase biosecurity between islands in the Canary Islands. Efficient management is urgently required to prevent the kingsnake from further expanding its range both on Gran Canaria and on other islands in the archipelago (Piquet and López-Darias 2021). Translocations of lizards to reinforce local subpopulations may also be effective in at least preventing complete local extinction (Piquet and López-Darias 2021). Further research is required into the impacts of invasive snakes more broadly (Piquet and López-Darias 2021). Ecological and genetic divergence between the species' two recognised morphs need to be taken into account in conservation planning, with most of the sites so far impacted by the snake lying within the range of the northern morph as characterised by Suárez et al. (2014).