Clianthus puniceus, following decisions reached by Heenan (2000) is treated as a separate species from C. magnificus based on minor foliage and floral differences. These were summarized by de Lange (2023) who noted that C. puniceus has mat-green foliage, and an upper leaf surface that is often slightly glaucous in colour. C. magnificus leaves are dark green, and the upper leaf surface very glossy. C. puniceus flowers are slightly smaller, the standard is conspicuously striped white, and the spur blotched or striped white as well. C. magnificus flowers are larger, very dark red, blotched dark purple-black near the base (very rarely with a few faint white stripes) and the spur is uniformly dark red.

However, mostly unpublished genetic studies show little difference between these two species, and Song et al. (2008) based on their molecular studies suggested that northern Tairawhiti populations (Clianthus magnificus) had the same sequence as C. puniceus from Moturemu, Kaipara Harbour. Nevertheless, for now they are maintained as distinct species.

Clianthus puniceus is a shrub, endemic to Aotearoa / New Zealand, where it was only known from Te Ika a Maui / North Island. The last subpopulation of this species in situ was extirpated around 2015, confirmed by exhaustive surveys, and the New Zealand Threat Classification System assessed this species as ‘Threatened / Nationally Critical’ Qualified ‘Conservation Dependent' and ‘Extinct in the Wild' (de Lange et al. 2018). The species is here assessed as Extinct in the Wild.

This species is endemic to Aotearoa / New Zealand, where it occurred on Te Ika a Maui / North Island. As circumscribed by Heenan (2000) it was known only from Auckland and Northland. There are no extant subpopulations, the last wild one, found on Moturemu Island, Kaipara Harbour was extirpated c. 2015. Few herbarium specimens from supposed wild subpopulations are known but it seems that the species was once present on islands in the Bay of Islands, on Limestone Island, Whangarei and from Motukaraka / Flat Island near Auckland. Many literature records are not supported with herbarium specimens leaving it unclear if Clianthus puniceus or C. magnificus was present, or indeed if the records were from garden plants or genuinely wild occurrences.

There are no wild plants / subpopulations known of this species. The species is now regarded as ‘Extinct in the Wild’, the last known wild subpopulation (Moturemu Island, Kaipara Harbour) died out about 2015 (de Lange et al. 2018).

The ecology of Clianthus puniceus is unknown, though it was likely to have been like that reported for Clianthus magnificus by Shaw and Burns (1997) (as Clianthus puniceus) which is typically found in early to mid-successional shrubland habitats often dominated by harakeke (Phormium tenax), wharariki (Phormium cookianum = P. colensoi; POWO 2023) and tutu (Coriaria arborea var. arborea) in coastal and lowland habitats. On Moturemu Island plants grew at the base of an unstable cliff face in colluvium in low windshorn coastal shrubland. As with Clianthus magnificus the exact ecology of Clianthus puniceus is muddied by the fact it was planted widely by Māori, and it is possible that some sites stem from past plantings (de Lange et al. 2010, de Lange 2023).

Clianthus puniceus was already a scarce plant by the time resident botanists started exploring the flora of Aotearoa / New Zealand. Few genuinely wild occurrences were reported between the 1830's and 1960's and it is possible that all the sites noted in literature stem from Māori plantings. The reason for this species' scarcity is not clear but irrespective, it has the same vulnerabilities known from Clianthus magnificus i.e., susceptibility to browsing animals such as feral goats (Capra hircus), red deer (Cervus elaphus) and possums (Trichosurus vulpecula). At Moturemu Island plants were reported in the 1960's and 1970's then again in the late 1980's and early 1990's. At this site it was surmised that plants were growing in suboptimal conditions – on the assumption at that time that the ecology of Clianthus magnificus and Clianthus puniceus (then treated as one species) were the same (Shaw and Burns 1997). This led to seedlings being removed from the island and grown on in ‘safe sites’ on Tiritirimatangi Island and the Auckland Botanic Gardens. The Moturemu Island plants were noted to be short-lived, succumbing to drought, rat browsing (despite rat control) and being outcompeted by taller woody invasive plants. The loss of the Moturemu Island population was probably hastened by the inaccessibility of the location which prevented regular monitoring.

This species is occasionally cultivated both in Aotearoa / New Zealand and internationally. Most plants sold by nurseries are Clianthus magnificus, usually marketed as C. puniceus ‘Kaka King’ or C. maximus ‘Kaka King’. A white-flowered race is also known. When Clianthus magnificus became commercially available it rapidly supplanted C. puniceus as the latest ‘fad’ plant, and now genuine C. puniceus is rarely seen in cultivation or for sale.

Clianthus puniceus is a taonga (treasure) to Auckland and Northland iwi. As such, some iwi have nurseries growing the species and there have been attempted plantings on Motuarohia (Bay of Islands), Limestone Island (Whangarei Harbour), Tiritirimatangi and Motuihe islands (Hauraki Gulf). Plantings have also been made on restoration land managed by the New Zealand Forest Restoration Trust along the south-western shore of the Kaipara Harbour. All these plantings have used Moturemu Island plants and so represent one lineage only. It has been suggested that efforts are made to secure seed from cultivated C. puniceus worldwide on the assumption that these may add to the existing genetic diversity because they may represent provenances that have died out in Aotearoa / New Zealand. 

Despite plantings, without regular weeding and control of browsing animals, including introduced slugs and snails, plants are rarely persistent. Natural recruitment from plantings has yet to be observed. As with Clianthus magnificus, hand clearing of competing weeds and spraying of plants for insect pests and diseases, as well as using sprays to deter browsing animals could be used to maintain and enhance plantings.

New Zealand Threat Classification System assessed this species as ‘Threatened / Nationally Critical’ Qualified ‘CD’ [Conservation Dependent], ‘EW’ [Extinct in the Wild] (de Lange et al. 2018).