Assessment Rationale:

Trigoniophthalmus borgesi is an endemic bristletail species present in six islands of the Azorean archipelago (Faial, Pico, Terceira, São Jorge, São Miguel and Santa Maria) (Borges et al. 2010), being known from nine Natural Forest Reserves of the islands. It has a large extent of occurrence (EOO =  ca. 22,600 km²) and a relatively small area of occupancy (AOO = 100 km²). The species is abundant in the canopies and trunks of native forests and known from at least 13 fragmented populations. In the past, the species has probably strongly declined due to changes in habitat size and quality. The main threat to this species will be habitat decline as a consequence of invasive species and climate change (increasing number of droughts) (Ferreira et al. 2016). Based upon the small area of occupancy and decreasing quality of the habitat it is assessed as Endangered.

Geographic Range:

Trigoniophthalmus borgesi is an endemic bristletail species present in six islands of the Azorean archipelago (Faial, Pico, Terceira, São Jorge, São Miguel and Santa Maria) (Borges et al. 2010). Within these six islands it is known from nine Natural Forest Reserves: Mistério da Prainha (Pico); Topo (S. Jorge); Biscoito da Ferraria, Pico Galhardo, Caldeira Guilherme Moniz, Caldeira Sta. Bárbara e Mistérios Negros and Terra Brava (Terceira); Atalhada (S. Miguel) and Pico Alto (Sta. Maria). The extent of occurrence (EOO) is ca 22,600 km² and the maximum estimated area of occupancy (AOO) is 100 km².

Population:

Trigoniophthalmus borgesi is a widespread and highly abundant species. The species presents a stable population and exists in six islands. We assume no impact for the population.

Habitat and Ecology

This species occurs mainly in the Azorean native forest. It is a generalist phytophagous species that feeds on algae and lichens. It is abundant in the canopies and trunks of endemic trees but can also be found on the forest floor, being active mostly in the twilight and night. The altitudinal range is between 300 and 1200 m. Based on seasonal data from SLAM traps obtained in several islands between 2012 and 2016, the adults are active all year, being most abundant in spring and summer (Borges et al. 2017).

Major Threat(s):

In the past, the species has probably strongly declined due to changes in habitat size and quality (Triantis et al. 2010, Terzopoulou et al. 2015). The main current threat is the spread of invasive species namely Pittosporum undulatum and Hedychium gardenerianum. Based on Ferreira et al. (2016) the habitat will further decline as a consequence of climate change (increasing number of droughts and habitat shifting & alteration).

Conservation Actions

The species is not protected by regional law. Its habitat is in regionally protected areas (Natural Parks of Faial, Pico, S. Jorge, Terceira, S. Miguel and Sta. Maria). Further research is needed to monitor the species and conservation measures to control the invasive Hedychium gardnerianum should be implemented to improve habitat quality for this species. Degraded habitats should be restored and a strategy needs to be developed to address the future threat by climate change. It is necessary a monitoring plan for the invertebrate community in the habitat in order to contribute to the conservation of this species. A habitat management plan is needed and anticipated to be developed during the coming years. Monitoring every ten years using the BALA protocol will inform about habitat quality (see e.g. Gaspar et al. 2010).