The Essex Naturalist
79
The Distribution Maps and Species Accounts
The county boundary used here is Watsonian Essex as defined by the Ray
Society publication No. 146 'Watsonian Vice-counties of Great Britain'. The
distribution maps have been produced using Dmap, a mapping program
developed by Dr Alan Morton. Tetrad maps have been chosen as a compromise
between recording coverage and the ease of assessing distribution patterns. It
has not been possible to obtain the Essex data used in the provisional atlas for
ants of the British Isles (Barrett, 1979). Where there is no recent data for a
10km Square shown in Barrett, this is noted in the species accounts.
Circles represent records from a tetrad within the county. Some records
represent just a single individual but most are for numbers of individuals or
populations. Post 1980 records are shown as closed circles, pre 1980 records as
open circles. Frequency Ratio, Tetrad Percentage and Recorded 1km sq.
percentage are discussed and defined earlier in the text. The Frequency Ratio is
the proportion of post 1980 tetrad to 10km square records; Tetrad Percentage is
the number of post 1980 tetrad records as a percentage of the total 990 tetrads in
the county; Recorded 1km sq. percentage is the number of post 1980 1km square
records as a percentage of the 484 one km squares in the county with ant
records.
FORMICOIDEA
FORMICIDAE ANTS
SUBFAMILY PONERINAE
Ponera coarctata (L.)
National status Scarce-Nb County status Essex Scarce
Threat status Essex Threatened Frequency Ratio 1.0
Tetrad Percentage 0.6 Recorded 1km sq. percentage 1.2
Distribution
Listed for S Essex in Falk (1991). Rare with records only for six localities, at
Aveley Clay Pit and Hackney Sewage Works (Plant et al.1985), Barling
(undated, M. Hanson), Connaught Club (Hanson 1992), Goshams Farm
Tilbury (taken by CW. Plant in 1997) and Colchester Roman Wall (taken by J.
Bowdrey in 1994).
Records shown in Barrett (1979) for TQ47 and TQ57 probably originate from
Kent.
Habitat and Ecology
In Essex it has been found in sparsely vegetated sites. A secretive species which
forms small colonies with 12-35 workers (Collingwood 1979), usually beneath
stones and other objects. It is found beneath stones, mosses and litter in a range
of situations including open stony ground, quarries, banks and landslips and
workers retreat rapidly into crevices when disturbed (Falk 1991).