Ero aphana (Araneae: Mimetidae), a spider new to Essex
Common, Surrey (Askins & Jones 1998, Harvey et al. 2002). It is currently listed as Nationally
Vulnerable [RDB2] in Bratton (1991). It has been found in Britain on dry heathland in the building
and mature phases, with some patches of bare stony ground and Ulex europaeus and Pinus sylvestris
present.
However, there is increasing evidence that the range of the species is expanding and that the spider
may now be found in a range of other habitats. In 2002 Clive McCarthy found the species within a
garden shed in a suburban garden in Surrey (McCarthy 2002). The first Anchor Field specimen was
collected on 26lh May 2003, when single female was beaten from the lower branches of hawthorn
growing at the edge of tall open grassland. Remarkably the same day an email was received from
Dr Steve Hopkin about a female Ero aphana found by one of his undergraduate students attending
the Reading University Biology of Spiders course. This specimen was found on 20th May 2003 in a
horsebox full of hay at Kingsclere near Basingstoke. The horsebox contained hay taken from several
fields in the vicinity of Waifs Farm (SU530611), VC 12 (North Hampshire). The student returned
to search elsewhere on the farm for further examples (including a male) but so far to no avail
(Harvey & Hopkin 2003). During a second visit to Anchor Field on 6th June a second female Ero
aphana was found, this time beaten from the lower branches of a gorse bush at the western edge of
the site.
Even more remarkably Dr Jonty Denton was up early on the 7th August 2003 sorting through the
previous nights moth catch, when the post arrived. Opening the latest BAS Newsletter he was
distracted from assorted Lepidoptera, and muesli, by the article on Ero aphana. Reading the
concluding remark of 'keep a look out' Jonty tossed the newsletter onto the table with a brooding
'mmmmmm', and shovelled up another heap of cereal, only to stop half way from the bowl. The
newsletter collided with the moth-trap light and out of the corner of his eye he noticed a spider
wobbling from its thread attached alongside the rain guard. It was an adult female Ero aphana, the
first he had ever seen! (Denton 2004).
The species may have colonised Britain relatively recently (Dr Peter Merrett pers. comm.) and is
still spreading, and/or climate change maybe a factor. Whatever the reason, it would seem that Ero
aphana could now turn up in a range of warm habitats in southern England.
Anchor Field lies in a region of south Essex that is geologically complex with a Chalk outcrop
north of the Thames variously overlain with sands, and so the vegetation frequently has areas
containing plants normally associated with chalk grassland adjacent to or mixed with areas containing
acid grassland plants. The area has been quarried over a long period of time, since at least the 16th
century, but in modern times mineral extraction became much more extensive and the area between
Purfleet and Grays contained a remarkable complex of old quarries. Unfortunately local councillors
and planners have long viewed these quarries as an eyesore and blight on the region, and most have
already been lost to industrial and retail use, and to massive housing developments such as 'Chafford
Hundred'. Thurrock intends to allow development of almost all those left.
The site overlooks the Thames and runs down from the south-eastern edge of the Lakeside Chalk
quarry towards the Thames. It appears to represent a survival of the original south-facing scarp at
the original pre-quarry land level of the chalk and overlying sands. At the southwestern end there is
extensive mature scrub with smaller open areas. The bulk of the site represents grassland, with
allotments, some disused, at the southeastern end. The substrate is presumably a complex of sands
and Chalk, the calcicolous nature of at least some areas demonstrated by the presence of the Essex
48
Essex Naturalist (New Series) 21 (2004)