Countries of Occurrence:
Saint Helena - British Overseas Territory
Pryce, D. & White, L.
Facilitators / Compilers/s:
This dead wood specialist was recently found at eight locations along the ‘High Central Ridge’ from Hooper’s Rock to Teutonic Hall (Mendel, Ashmole and Ashmole 2008). During the 1960s the species was present at 16 locations (Basilewsky 1972) but many of these have not been resurveyed; there are 18 locations if the data is combined. This species has been recorded from both endemic and non-native species including Gorse (Ulex europaeus L.) and Thorn Tree (Erythrina caffra Thunb.). While the majority of records are from endemic plant material this may be a result of sampling bias towards these species. There has, however, also been a decline in habitat quality across the entire range of the species with the loss of several important endemic habitat fragments and an increase in invasive non-native weeds and predatory invertebrates (e.g. Formicidae). As this species is able to utilise non-native species and many previously known sites remain unsurveyed it is likely to occur at other locations within its range, but will be increasingly reliant on non-native species at these sites. The species has a very low EOO (32 km²) and AOO (24 km²) and the number of current locations is probably somewhere between 10 and 18. Therefore we assess this species as Near Threatened as the loss of any further locations and consequent potential decline in EOO and AOO is plausible with continuing habitat decline and the spread of alien invasive species.
Endemic to the island of St Helena, in the South Atlantic Ocean, where it is restricted to intermediate and higher elevations in the ‘Green Heartland’ of the island
This species appears to have a preference for the dead wood of endemic plant species (Basilewsky 1972); however, this may be a result of sampling bias towards this material. Since the major surveys of the mid- to late-1960s there has been a general decline in habitat quality with the loss of several important endemic habitat fragments where this species was found. There has also been an increase in invasive non-native predatory species (e.g. Formicidae) that share its microhabitat. It is therefore inferred that the population is declining.
Larvae of this species feed on dead and rotting material from woody plants in more humid habitats at middle and upper elevations on the island. It has been reported from the endemic plant species Whitewood (Petrobium arboreum (J.R. Forst. & G. Forst.) R. Br.), Black Cabbage Tree (Melanodendron integrifolium (Roxb.), Gumwood (Commidendrum robustum (Roxb.)), She Cabbage Tree (Lachanodes aroborea (Roxb.) B.Nord.) and Bellflower (Wahlenbergia sp.) and the non-native species Gorse (Ulex europaeus L.), Caffra Thorn Tree (Erythrina caffra Thunb.) and an unidentified species of the family Solanaceae (Basilewsky 1972). The adults probably feed on rotting organic matter and various fungi associated with this material
Since the major surveys of the mid- to late-1960s there has been a general decline in habitat quality with the loss of several important endemic habitat fragments where this species was found. There has also been an increase in invasive non-native predatory species (e.g. Formicidae) that share its microhabitat
Survey work should be undertaken at sites where the species was previously found at in the mid- to late-1960s to determine if it is still present. Special attention should be given to sites where endemic plant habitat fragments have been lost since this time. Any research and monitoring of this species would be of value. Of critical importance is the continued expansion and linking of habitat fragments as well as removal of invasive non-native species where this is possible.