CRCritically Endangered

Tetrablemma helenense

Tetrablemma helenense is a small spider species endemic to St. Helena, a remote volcanic island in the South Atlantic Ocean.

Decreasing

Population trend

1

Countries

01Classification

Taxonomy & Classification

Kingdom

ANIMALIA

Phylum

ARTHROPODA

Class

ARACHNIDA

Order

ARANEAE

Family

TETRABLEMMIDAE

Genus

Tetrablemma

Tetrablemma helenense belongs to the family TETRABLEMMIDAE, order ARANEAE, within the ARACHNIDA class.

02Description

Species Profile

Tetrablemma helenense is a small spider species endemic to St. Helena, a remote volcanic island in the South Atlantic Ocean. This arachnid belongs to the family Tetrablemmidae, characterized by their distinctive four-eyed arrangement and compact body structure. The species is found exclusively within the island's unique terrestrial ecosystems, which have evolved in isolation over millions of years. St. Helena's endemic fauna faces severe conservation challenges due to the island's small size and limited habitat availability. The primary threats to T. helenense include habitat destruction from human development, invasive plant species that alter native vegetation communities, and the introduction of non-native predators and competitors. The island's fragile ecosystems have been significantly modified since human colonization, with much of the original vegetation cleared for agriculture and settlement. Climate change poses additional risks through potential shifts in temperature and precipitation patterns that could affect the spider's microhabitat requirements. Conservation efforts on St. Helena focus on habitat restoration, invasive species control, and protection of remaining native vegetation areas. The St. Helena National Trust and other organizations work to preserve critical habitats and conduct research on endemic species. However, the extremely limited range and small population size make T. helenense particularly vulnerable to extinction. Continued monitoring and targeted conservation actions are essential for the species' survival, though the challenges of protecting biodiversity on such a small, isolated island remain substantial.

Tetrablemma helenense faces severe threats from habitat destruction caused by human development and agricultural activities on St. Helena. Invasive plant species have significantly altered the island's native vegetation communities, disrupting the spider's natural habitat requirements. The introduction of non-native predators and competitors further threatens the survival of this endemic species.

Key Facts

IUCN StatusCritically Endangered (CR)
TrendDecreasing
GroupArachnids
03Habitat

Habitat & Distribution

Tetrablemma helenense inhabits the terrestrial ecosystems of St. Helena, likely associated with native vegetation communities and soil environments. The species requires the specific microhabitat conditions found within the island's unique endemic plant communities.

Rocky areasMajor
04Threats

Threats

!

IUCN Red List: Critically Endangered

Tetrablemma helenense faces severe threats from habitat destruction caused by human development and agricultural activities on St. Helena. Invasive plant species have significantly altered the island's native vegetation communities, disrupting the spider's natural habitat requirements. The introduction of non-native predators and competitors further threatens the survival of this endemic species.

Commercial & industrial areas

Ongoing

Housing & urban areas

Ongoing

Invasive non-native/alien species/diseases

Ongoing

Roads & railroads

Ongoing
05Conservation

Conservation Actions

Site/area protection
Species management
Species recovery
06Range

Found in 1 Country

Community

Community Sightings

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07Sources

Sources & Attribution

How to Cite

IUCN: IUCN (2025). The IUCN Red List of Threatened Species. Version 2025-1. Available at: https://www.iucnredlist.org. doi:10.2305/IUCN.UK.2025-1.RLTS

GBIF: GBIF.org (2025). GBIF Home Page. Available at: https://www.gbif.org

This page: SpeciesRadar (2025). Tetrablemma helenense (Tetrablemma helenense). SpeciesRadar: Intelligence for Earth's Biodiversity. Available at: https://speciesradar.org/species/ruperts-valley-spider

Full citation guide & data usage terms