Assessment Rationale:

The Palma Stick Grasshopper (Acrostira euphorbiae) is endemic to La Palma and has a very small extent of occurrence (< 20 km²). The only location of this species is strongly affected by overgrazing and logging of its main food plant, Euphorbia lamarckii, as well as wildfires. There is a continuing decline in the extent of occurrence, area of occupancy, extent and quality of habitat, number of subpopulations as well as in the number of mature individuals. Furthermore, the population is very small (200 mature individuals) and all individuals are found in a single subpopulation. Therefore, the species is assessed as Critically Endangered (CR).

Geographic Range:

This species is endemic to the southwestern part of La Palma (Canary Islands, Spain) (López et al. 2003, 2007). The area of occupancy (AOO) is 20 km² and its extent of occurrence (EOO) is here also estimated as 20 km² (even though calculated with a minimum convex polygon it is c. 8 km²).

Population:

The population size is very small (c. 200 mature individuals) and is currently decreasing. From 2003 to 2008 the population decreased by 68%. There is a continuing decline in the extent of occurrence, area of occupancy, extent and quality of habitat, number of subpopulations as well as in the number of mature individuals.

Habitat and Ecology

The species occurs in scrubland dominated by Euphorbia lamarckii. Acrostira euphorbiaedwells and feeds only on this bush. Its altitudinal range is 40 - 680 m.

Major Threat(s):

The insect is threatened by illegal logging of Euphorbia lamarckii, overgrazing and wildfires. Increased grazing leads to the ongoing degradation of its habitat. Previous plans of building a golf course in its main habitat have meanwhile been stopped. Its habitat is found in an area, which is very likely to be destroyed by future land slides and may also be affected by tsunamis. On the basis of any of this threats, only one location has been estimated.

Conservation Actions

The species is currently listed as Endangered on the Spanish Red List (Verdú et al. 2006) and protected by law. Recent plans to build a golf course in its habitat have been abandoned (H. López pers. comm. 2015). There is a need for better protection of its habitat as well as the raising of awareness and legislation. Furthermore, there is a need for research on its ecology (particularly on the question of why this species seems to be restricted to a single food plant, which is not the case for its relatives on other islands). Finally, a strategic species conservation plan would be very useful to protect this species. A monitoring program of its population and habitat should be established.