Longitarsus helenae is a flea beetle endemic to the island of St Helena and is found in the high altitude cloud forest habitat. It was first recorded in 1860 and was last seen in 1967. It has been recorded from a number of endemic host plants, which could include Black Cabbage (Melanodendron integrifolium – Vulnerable), She-cabbage (Lachanodes arborea – Extinct in the WildW) and He-cabbage (Pladaroxylon leucodendron – Critically Endangered), Lobelia (Trimeris scaevolifolia – Vulnerable), Jellico (Berula burchellii – Endangered) and St Helena Dogwood (Nesohedyotis arborea – Critically Endangered) (Lambdon and Ellick 2016), as well as being found on the introduced Arum Lily (Zantedeschia aethiopica), which is considered invasive on St Helena. Endemic cloud forest host plants are under threat from climate change, invasive non-native species of trees and shrubs, as well as New Zealand Flax (Phormium tenax) (impacting host trees), invasive non-native invertebrates, and the recent spread of fungal diseases, including Phytophthora spp., on cloud forest trees, will seriously threaten this species. Populations present on non-native plant species are under threat from habitat deterioration and loss from drivers of change including climate change and invasive non-native species. Invasive non-native predatory animal species will also seriously threaten this species. The family Chrysomelidae is notably underrepresented on St Helena. This flea beetle was last recorded in 1967, despite extensive surveys between 2005 and 2017 and requires further survey work, particularly any specificity to host plants. Its extent of occurrence (EOO) and area of occupancy (AOO) are both 12 km², it is known from a single location (and only from old records), and it is undergoing a continuing decline in habitat due to the above described threats to the cloud forest. This species is assessed as Critically Endangered (Possibly Extinct).

Longitarsus helenae is a chrysomelid beetle endemic to the island of St Helena, in the South Atlantic. It was recorded in 1860 by Bewicke between Mount Actaeon/Cuckhold’s Point and Diana's Peak. Melliss recorded it in 1865 (from an unspecified location) and Wollaston, in 1875, recorded it from the High Central Ridge where he described the species as widespread in Cabbage tree woodland at high altitude during his visit. It was also found in large numbers in 1967 by the Belgian survey at the High Central Ridge, Cabbage Tree Road, and High Peak. However, there was an apparent large decline by the time Mendel, Ashmole and Ashmole undertook their surveys in 2005-6, as it was not found despite specifically searching one of the host plants (Lobelia). They concluded that the species “must now be very scarce if not extinct”. Please note there are historical changes with the site names for Diana’s Peak, Cuckhold’s Point and Mt Actaeon and as such, we are including all the names in this assessment for the location of the records; see St Helena Government (2020).

This species was first recorded in 1860 by Bewicke between Mount Actaeon/Cuckhold’s Point and Diana's Peak. Melliss recorded it in 1865 (from an unspecified location) and Wollaston, in 1875, recorded it from the High Central Ridge where he described the species as widespread in Cabbage tree woodland at high altitude during his visit. It was also found in large numbers in 1967 by the Belgian survey at the High Central Ridge, Cabbage Tree Road, and High Peak. However, there was an apparent large decline by the time Mendel, Ashmole and Ashmole undertook their surveys in 2005-6, as it was not found despite specifically searching one of the host plants (Lobelia). They concluded that the species “must now be very scarce if not extinct”. Please note there are historical changes with the site names for Diana’s Peak, Cuckhold’s Point and Mt Actaeon and as such, we are including all the names in this assessment for the location of the records.

This species has been recorded from a number of endemic host plants: Cabbage trees: these could include Black Cabbage (Melanodendron integrifolium – Vulnerable), She-cabbage (Lachanodes arborea – Extinct in the Wild) and He-cabbage (Pladaroxylon leucodendron  – Critically Endangered), Lobelia (Trimeris scaevolifolia – Vulnerable), Jellico (Berula burchellii – Endangered) and St Helena Dogwood (Nesohedyotis arborea – Critically Endangered) (Lambdon and Ellick 2016), all of which have a limited distribution on St Helena. It was also recorded on the introduced Arum lily Zantedeschia aethiopica which is considered invasive on St Helena and is common in the uplands of the island. Further surveys are needed to determine any specificity to host plants.

This species was last recorded in 1967 in the cloud forest, and has been recorded on a number of endemic plant species such as Cabbage trees, but also on the non-native Arum lily. The cloud forest host trees have ongoing threats including climate change, intense competition from invasive non-native plant trees, shrubs and other plant species, including New Zealand Flax (Phormium tenax). The recent arrival and spread of fungal tree diseases including Phytophthora spp, on cloud forest trees, will seriously threaten this species. Populations present on non-native plant species are under threat from habitat deterioration and loss from drivers of change including climate change and invasive non-native species. Species of non-native predatory vertebrates (such as African Grass Frog, Strongylopus grayi) and invertebrates (such as ants, rove beetles, spiders and centipedes) are also likely to impact this species negatively.

This species is on the Environmental Protection Ordinance on St Helena, which indicates protected species. The Peaks are currently within a protected area and part of the government’s Nature Conservation Area (NCAs). If extant, this species will benefit fromthe habitat improvement outlined in the Peaks National Park Management Plan (2019). There is currently no specific action plan for this species, but its conservation and further research will be supported through the St Helena Invertebrate Strategy 2023–2027 (St Helena National Trust and St Helena Government 2023).