Assessment Rationale:

Neomariania incertella is a single island endemic species restricted to Flores island (Azores, Portugal) (Borges et al. 2010). It has a very small extent of occurrence (EOO = 4 km²) and area of occupancy (AOO = 4 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 major land-use change in the last 100 years and recent intensification in cattle production. Main recent past and ongoing threats are the invasive plants Pittosporum undulatum, Hydrangea macrophylla and Hedychium gardnerianum that are changing the habitat. Based on Ferreira et al. (2016) the habitat will further decline as a consequence of climate change. Based upon the small geographic range of the species with only one location and continuing decline of its habitat area and quality, it is assessed as Critically Endangered.

Geographic Range:

Neomariania incertella is a single island endemic species restricted to Flores island (Azores, Portugal) (Borges et al., 2010), known from native forest and in open landscapes with isolated tree groups. The extent of occurrence (EOO) is 4 km² and the maximum estimated area of occupancy (AOO) is 4 km².

Population:

This species is rare in Flores island, occurring mostly in native vegetation but also in naturalized plants in a small patch of native vegetation in the North part of the island. A continuing decline in the number of mature individuals is inferred from the degradation of its habitat due to human activities (pastures for dairy cattle) and invasions of alien plants.

Habitat and Ecology

The species occurs in native forest areas but also in open landscapes with isolated tree groups. Possibly, the larvae feed on fruit and flowers such as Fabaceae and Moraceae, also in sporangia of ferns; the adult flies in June (Rebel 1940). Altitudinal range: 10-100 m.

Major Threat(s):

In the past, the species has probably strongly declined due to changes in habitat size and quality, mostly the creation of pastures (Triantis et al. 2010). Currently invasive plants Pittosporum undulatum, Hydrangea macrophylla and Hedychium gardnerianum are changing some of the areas and decreasing the quality of the 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 & alteration).

Conservation Actions

The species is not protected by regional law. Its habitat is in regionally protected areas (Natural Parks of Flores). Further research is needed to monitor the species and conservation measures to control the invasive Hedychium gardnerianum, Hydrangea macrophylla and Pittosporum undulatum should be implemented to improve habitat quality for this species. Additional research is needed into its ecology and life history in order to find extant specimens. 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.