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Labidura herculeana

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA ARTHROPODA INSECTA DERMAPTERA LABIDURIDAE

Scientific Name: Labidura herculeana
Species Authority: (Fabricius, 1798)
Common Name(s):
English St Helena Giant Earwig, St Helena Earwig, Saint Helena Earwig
Synonym(s):
Labidura loveridgei Zeuner, 1962
Taxonomic Notes: Originally described as a full species, this taxon was downgraded to a subspecies of L. riparia by Kirby (1904). The taxon was reinstated as a valid species by Brindle (1970) and synonymised with L. loveridgei Zeuner, 1962 which had been described from subfossil forceps.

Assessment Information [top]

Red List Category & Criteria: Extinct ver 3.1
Year Published: 2014
Date Assessed: 2014-08-22
Assessor(s): Pryce, D. & White, L.
Reviewer(s): Gerlach, J.
Justification:
This is the world’s largest known earwig, attaining a length of up to 80 mm. A total of 40 specimens were collected from the Horse Point area during the two Belgian expeditions from the Royal Museum for Central Africa in 1965-6 and 1967 (Brindle 1970). Live specimens were not found at any other sites at this time although they reported fragments of dead individuals from the south and east flanks of Flagstaff. There are a couple of unconfirmed records that the species was present after this time and it was thought to be declining. Two expeditions were conducted by Paul Pearce-Kelly from the London Zoo in 1988 and 1993, however, they failed to find any trace of the species. Recent intensive survey work in the 1990s and 2000s by Philip and Myrtle Ashmole failed to locate the species in this or nearby areas (Ashmole and Ashmole 2003). Howard Mendel from the Natural History Museum in London also failed to find it during a visit with the Ashmoles in 2005-6. The habitat at Horse Point has been degraded as far as this species is concerned since the time of the Belgian expeditions by the removal of nearly all surface stones, under which specimens were then found, for construction purposes. There has also been potential increased predator pressure from mice and rats, and probably also from invasive non-native predatory invertebrates including spiders and the centipede Scolopendra morsitans Linnaeus, 1758. The only possible evidence that this species may have persisted beyond the time of the Belgian expeditions has been the discovery of fragments of dead individuals. A sub-fossil forcep and ninth abdominal tergite was found with bird bones in 1995 near Prosperous Bay. Two further ninth abdominal tergites have been recovered since. The first was found under a discarded piece of equipment in the centre of Horse Point Plain in 2013; the second in a small area at the Millennium Forest in 2014 where some remaining surface rock is present. However, this second fragment was found in a concentration of invertebrate remains in the lair of a predatory spider. As all of these remains are fragmentary and the insect itself relatively robust with remains persisting potentially for many decades it has to be assumed that these specimens had been dead for a considerable time. The species is large, charismatic and of iconic status on the island; while there is still a slim possibility that it may still persist in some remote location, the balance of evidence points towards the species being extinct. The last confirmed adult sighting was in May 1967.
History:
1996 Critically Endangered
1994 Endangered (Groombridge 1994)
1990 Endangered (IUCN 1990)
1988 Endangered (IUCN Conservation Monitoring Centre 1988)
1986 Endangered (IUCN Conservation Monitoring Centre 1986)

Geographic Range [top]

Range Description: Labidura herculeana is endemic to the island of St Helena in the South Atlantic Ocean and its last known sites are restricted to the Eastern Arid Area. The only known site where live adults have been found is Horse Point Plain. Fragments have also been found at the lowest end of the Millennium Forest adjacent to Horse Point Plain and at a sub-fossil bird bone deposit in the hinterland behind Prosperous Bay and in the past on the south and east flanks of Flagstaff.
Countries:
Regionally extinct:
Saint Helena, Ascension and Tristan da Cunha (Saint Helena (main island))
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: No live specimens have been found since 1967.
Population Trend: Unknown

Habitat and Ecology [top]

Habitat and Ecology: The species is xerophilus and nocturnal. At Horse Point the species was mostly found in burrows beneath stones with the adults appearing during the summer rains (December to February), seeking shelter again at the onset of drier weather (Brindle 1970). The burrows extended for a considerable distance and eventually become lost in fissures in the soil. When disturbed the adults tried to escape by running into these burrows. Mating was observed twice on 22/12/1965 and 1/2/1967 and a females with eggs were observed on 8/3/1967 and 24/3/1967. It is possible that in the past the species also inhabited bird colonies as indicated by its presence as a sub-fossil with bird bones.
Systems: Terrestrial

Threats [top]

Major Threat(s):

There has been a general decline in habitat quality and an increase in the number of invasive non-native predators including rats, mice, spiders and the centipede Scolopendra morsitans Linnaeus, 1758. Habitat has also been altered in the past due to removal of surface stones for building.

Conservation Actions [top]

Conservation Actions: A watching brief should be maintained for this species.

Citation: Pryce, D. & White, L. 2014. Labidura herculeana. The IUCN Red List of Threatened Species. Version 2014.3. <www.iucnredlist.org>. Downloaded on 24 November 2014.
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