Red List of South African Species

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Vulnerable (VU)
Assessors: Vanessa Couldridge Corinna Bazelet
Contributors: Anja Danielczak
Reviewers: Axel Hochkirch

Rationale

Bullacris obliqua is endemic to the south-western regions of South Africa, where it has an estimated area of occupancy (AOO) of between 100 and 3,000 km². This has likely resulted from habitat destruction due to extensive urban development and farming across the geographic range of the species. The number of subpopulations and individuals is also inferred to be declining based on the species being relatively uncommon in the field, and undetected in certain areas of the Western Cape where it was historically recorded. The population is severely fragmented. The AOO is here assumed to be higher than 500 km² and lower than 2,000 km² and, therefore, it is classified as Vulnerable (VU).

Distribution

Bullacris obliqua is endemic to the west coast of South Africa, where it occurs in both the Western Cape and Northern Cape Provinces. It has a more patchy distribution than other Pneumoridae species inhabiting these areas. Its extent of occurrence (EOO) is ca 33,500 km² and its area of occupancy (AOO) is estimated to be between 100 and 3,000 km².

Population trend

Trend

Bullacris obliqua emerges seasonally, and has been observed from August to November. The species is not commonly encountered in the field, despite fairly extensive surveys within its geographical range. It also appears to be absent from some areas where it was historically recorded to occur. Therefore, a continuing decline in the number of subpopulations and the number of mature individuals is inferred. The species has a discontinuous distribution with very small subpopulations, and there is unlikely to be much gene flow between geographically separated subpopulations as females are flightless. Therefore, the population is considered severely fragmented. 

Threats

Potential threats to Bullacris obliqua include climate change resulting in a loss of habitat due to less rainfall and land use change as a result of urban development and agriculture.

Uses and trade

This species is not utilised.

Conservation

There are no conservation actions for the species, but it occurs in protected areas. Colour variation exists within the species, with some subpopulations having a distinctive and striking pattern of whitish stripes on a grey-green background, while other subpopulations are uniformly green without any stripes. It is morphologically somewhat similar to Bullacris discolor (Dirsh 1965), but easily distinguished by its very distinctive advertisement call. Research into its ecology, threats and population trend is required. Remaining habitats need to be protected to avoid future declines.

References 

[@electronic{2573,
 address = {www.iucnredlist.org},
 author = {IUCN},
 title = {The IUCN Red List of Threatened Species. Version 2018-1},
 year = {2018}
}
,@electronic{15431178,
 address = { http://Orthoptera.SpeciesFile.org},
 author = {Eades, D.C., Otte, D., Cigliano, M.M. and Braun, H.},
 title = {Orthoptera Species File. Version 5.0/5.0},
 year = {2014}
}
,@article{100946558,
 author = {Dirsh, V.M.},
 journal = {Bulletin of the British Museum (Natural History) Entomology },
 pages = {325--396},
 title = {Revision of the family Pneumoridae (Orthoptera: Acridoidea)},
 volume = {15.0},
 year = {1965}
}
,]
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