Bembidion rufosuffusum is a ground beetle species endemic to the island of St Helena and was found in the high altitude cloud forest habitat. It was first recorded in 1875 and last recorded in 1967. It is the smallest of its genus on the island. Found in trunks of St Helena Tree Fern (Dicksonia arborescens – Vulnerable) (Lambdon and Ellick 2016), under the bark of Cabbage tree wood: these could include Black Cabbage (Melanodendron integrifolium – Vulnerable), She-cabbage (Lachanodes arborea – Extinct in the Wild) and He-cabbage (Pladaroxylon leucodendron – Critically Endangered) (Lambdon and Ellick 2016), and in the caterpillar tunnels along the High Central Ridge. Despite St Helena Tree Fern having a stable population on St Helena, there are threats to the Cabbage trees in the cloud forest more widely including climate change, invasive non-native species of trees and shrubs, as well as New Zealand Flax (Phormium tenax). Species of non-native predatory animals are likely to impact this species negatively. Despite later comprehensive surveys between 2005 and 2017, this species has not been seen since 1967 and it requires further survey work. Its extent of occurrence (EOO) and area of occupancy (AOO) are both 0–4 km², it is known from a single location (and from old records) in the cloud forest, and is undergoing a continuing decline in habitat due to the threats described above. This species is Red Listed as Critically Endangered (Possibly Extinct).

Bembidion rufosuffusum is a ground beetle species endemic to the island of St Helena, in the South Atlantic. Eight specimens were collected by Wollaston in 1875 from Cuckholds Point/Mt. Actaeon/Diana’s Peak, and a ninth communicated to Wollaston by a Mr P. Whitehead collected in 1876 from between Diana’s Peak and Mount Actaeon/Cuckhold’s Point. Fifty-four specimens were collected from the High Central Ridge in 1967 from the ledge below Cuckhold’s Point/Mount Actaeon and Cabbage Tree road. The species has not been recorded since 1967.

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).

Eight specimens were collected by Wollaston in 1875 from Cuckholds Point/Mt. Actaeon/Diana’s Peak, and a ninth communicated to Wollaston by a Mr P. Whitehead collected in 1876 from between Diana’s Peak and Mount Actaeon/Cuckhold’s Point. Fifty-four specimens were collected from the High Central Ridge in 1967 from the ledge below Cuckhold’s Point/Mount Actaeon and Cabbage Tree road. The species has not been recorded since 1967.

Wollaston (1877) recorded the species mostly (but not solely) beneath the moist stems of St Helena Tree Fern (Dicksonia arborescens, assessed as Vulnerable) (Lambdon and Ellick 2016). It was also recorded from standing dead Cabbage tree wood: these could include Black Cabbage (Melanodendron integrifolium, assessed as Vulnerable), She-cabbage (Lachanodes arborea, assessed as Extinct in the Wild) and He-cabbage (Pladaroxylon leucodendron, assessed as Critically endangered) (Lambdon and Ellick 2016)), at heights of up to 2 m in both caterpillar tunnels and also under the bark of the Cabbage trees (Basilewsky 1972). It is likely to be predatory on other small invertebrates, possibly weevil and Fungus weevil (Anthribidae) larvae, possibly with a high degree of specificity to a particular prey taxon.

This species is under threat from the loss of the Cabbage trees and St Helena Tree Fern, to which this species seems to be confined. Endemic St Helena Tree Fern seem to have fairly stable populations, but Cabbage 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). It is not known whether the recent arrival and spread of fungal tree diseases, including Phytophthora spp., which are impacting some cloud forest trees, will also threaten St Helena Tree fern and therefore would seriously threaten this species.

Almost all the endemic species of this genus on St Helena, regardless of habitat, seem to have disappeared since the 1960s and it is likely that the same or similar, (but specifically unknown) factors have impinged on them all. It is possible that the plant litter habitat of all the species has been so severely modified by a large number detritivorous millipedes, woodlice and landhoppers as to become unsuitable, and/or that the introduction of predatory animal species (rodents or African Grass Frog, Strongylopus grayi) or other ground beetles and rove beetles either predated on all of the Bembidion species directly or negatively impacted their prey. The populations of the cloud forest plant species, specially Tree fern thicket, have very limited distributions and have an uncertain future.

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 from the 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).