Nothophantes horridus 

Scope: Global & Europe
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Arthropoda Arachnida Araneae Linyphiidae

Scientific Name: Nothophantes horridus Merrett & Stevens, 1995
Common Name(s):
English Horrid Ground-weaver
Taxonomic Source(s): Merrett, P. and Stevens, R.A. 1995. A new genus and species of linyphiid spider from south-west England (Araneae: Linyphiidae). Bulletin of the British Arachnological Society 10(3): 118-120.
Taxonomic Notes: The Horrid Ground-weaver (Nothophantes horridus Merrett & Stevens, 1995) is a recently described species of small linyphiid spider (total body length of just 2.5 mm). It is also the only known representative of the genus.

Assessment Information [top]

Red List Category & Criteria: Critically Endangered A3c ver 3.1
Year Published: 2015
Date Assessed: 2015-02-02
Assessor(s): Cardoso, P. & Hilton-Taylor, C.
Reviewer(s): Henriques, S. & Hochkirch, A.
Contributor(s): Smithers, P.
This spider has an extremely restricted range with a very small area of occupancy and extent of occurrence of <1 km2. One of the three locations where it has been recorded has been completely lost to development and there are proposals to develop the two remaining locations in the near future. This species is therefore highly threatened with extinction; 80-100% of the population could be lost within the next ten years if the developments go ahead, hence it qualifies for listing as Critically Endangered.

Geographic Range [top]

Range Description:This species is endemic to Plymouth, England (United Kingdom), where it is only known from two abandoned limestone quarries, Radford Quarry and Billacombe (occupying approx. 0.1 km2 in total). The type locality, Shapter’s Field Quarry (now Plymouth Trade Park) was recently lost to development. Both remaining sites are now under threat.
Countries occurrence:
United Kingdom (Great Britain)
Additional data:
Estimated area of occupancy (AOO) - km2:1Continuing decline in area of occupancy (AOO):Yes
Extreme fluctuations in area of occupancy (AOO):UnknownEstimated extent of occurrence (EOO) - km2:1
Continuing decline in extent of occurrence (EOO):YesExtreme fluctuations in extent of occurrence (EOO):Unknown
Number of Locations:2Continuing decline in number of locations:Yes
Extreme fluctuations in the number of locations:Unknown
Upper elevation limit (metres):20
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:No data on the population size of this species exist and hence we have used reduction in area of occupancy as a surrogate for population trend. The population trend is negative since one third of the known locations have lost suitable habitat conditions due to development and the two remaining sites are planned to follow the same route.
Current Population Trend:Decreasing
Additional data:
Continuing decline of mature individuals:Yes
Extreme fluctuations:UnknownPopulation severely fragmented:No
No. of subpopulations:2Continuing decline in subpopulations:Yes
Extreme fluctuations in subpopulations:UnknownAll individuals in one subpopulation:No

Habitat and Ecology [top]

Habitat and Ecology:Nothophantes horridus probably lives in narrow fissures in limestone (mesovoid shallow substratum - MSS), from which it occasionally emerges to hunt for small arthropod prey. On such occasions, it can be found under stones and debris on the floor and cliff faces of disused limestone quarries. This species is possibly a troglophyle, although it shows no adaptations to cave life besides numerous long spines on the legs and prominent bristles on the abdomen. Adult females have been recorded in March and April but males have only been found in March (Merrett and Stevens 1995, 1999).
Continuing decline in area, extent and/or quality of habitat:Yes
Generation Length (years):1
Movement patterns:Not a Migrant

Use and Trade [top]

Use and Trade: This species is not utilized.

Threats [top]

Major Threat(s): The type locality has already been extensively developed into the Plymouth Trade Park and there are development plans for the two remaining sites from where it has also been recorded.

Conservation Actions [top]

Conservation Actions: The species is listed as a UK Biodiversity Action Plan priority species and Natural Environment and Rural Communities Act 2006 - Species of Principal Importance in England. Radford Quarry has been designated a County Wildlife Site due to its limestone habitat which contains a number of other nationally scarce or rare plant and animal species (Allen 2011).

Citation: Cardoso, P. & Hilton-Taylor, C. 2015. Nothophantes horridus. The IUCN Red List of Threatened Species 2015: e.T70560176A70560214. . Downloaded on 20 August 2018.
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