Assessment Rationale:

Tarphius tornvalli is a single-island endemic species restricted to São Miguel island (Azores, Portugal) (Borges et al. 2010, 2017). It has an extent of occurrence of 380 km² and a reduced area of occupancy (AOO = 52 km²). There is a continuing decline in the EOO, AOO, extent and quality of habitat as well as the number of mature individuals as a result of the invasions of non-native plants. The species occurs mainly in the soil of native forests, but also under the bark of endemic and exotic trees and in dead wood. In the past, the species has probably strongly declined due to changes in habitat size. Therefore, we suggest as future measures of conservation: (1) a long-term monitoring plan of the species; and (2) control of invasive species, namely Hedychium gardnerianum.The species is assessed as Endangered (EN).

Geographic Range:

Tarphius tornvalli is a single-island endemic species restricted to São Miguel island (Azores, Portugal) (Borges et al. 2010, 2017), known from Natural Forest Reserves of Pico da Vara, Graminhais and Atalhada. The extent of occurrence (EOO) is ca 380 km² and the maximum estimated area of occupancy (AOO) is 52 km².

Population:

The species is abundant, particularly in the well preserved patches of native forests of S. Miguel island (Borges et al. 2017). A continuing decline in the number of mature individuals is inferred from monitoring schemes and from the ongoing habitat degradation due to invasions of alien plants (Hedychium gardnerianum) (Borges et al. 2017). This species is assessed here as severely fragmented as at least 50% of its population can be found in subpopulations that are 1) smaller than would be required to support a viable population, and 2) separated from other habitat patches by a large distance. In fact, the species occurs in fragments that are isolated in a matrix of pastures.

Habitat and Ecology

The species is particularly abundant, namely this species lives in the soil and occurring in some of the larger and well preserved patches of native forests of S. Miguel island. It also occurs under the bark of dead endemic and exotic trees (Borges et al. 2017). This species has an altitudinal range between 500 and 1000 m. It is a nocturnal fungivorous species.

Major Threat(s):

In the past, the species has probably strongly declined due to changes in habitat size and quality (Triantis et al. 2010). Currently, the rapid advance and expansion of invasive plants species is the major threat (Borges et al. 2017), particularly Hedychium gardnerianum and Pittosporum undulatum that are changing the habitat structure, namely decreasing the cover of bryophytes and ferns in the soil and promoting the spread of other plants.  The management of Cryptomeria japonica plantations could be  also a problem for the subpopulations living in this habitat. Based on Ferreira et al. (2016) the habitat will further decline as a consequence of climate change (increasing number of droughts and habitat shifting and alteration).

Conservation Actions

The species is not protected by regional law. Its habitat is in regionally protected areas (Natural Forest Reserves of Pico da Vara, Graminhais and Atalhada, in S. Miguel island). Degraded habitats should be restored with the removal of invasive species. A strategy needs also to be developed to address the future threat by climate change. A habitat management plan is needed and anticipated to be developed during the coming years. Since this species is an icone of the relict native Azorean forests, it is suggested that some awareness measures should be put in practice. Further research is needed into its ecology and life history in order to find extant specimens in additional areas in S. Miiguel namely in Lagoa do Fogo and Lagoa das Sete Cidades and obtain information on population size, distribution and trends. It is also necessary a monitoring plan for the invertebrate community in the habitat in order to contribute to perform a species potential recovery plan. Monitoring every ten years using the BALA protocol will inform about habitat quality (see e.g. Gaspar et al. 2011).