This article was published in The British Tarantula Society journal Vol: 24, No 4, 2009.

We've all heard jovial comments (I've made them myself) about describing Tegenaria gigantea the British 'T' due to its size, attitude and appetite, but if there is such an award available, it goes to Atypus affinis, a true Mygalomorph (Fig3).

A. affinis (the purse web spider) has massive, almost disproportionate, chelicerae that hinge in the vertical plane, and possesses two pairs of book lungs, not unlike the Tarantulas we all know and love.

Fig 3

History, Description & Distribution:

Atypus affinis (Eichwald 1830) had been a bit of a mystery, and had been confused with European trapdoor spiders (in fact originally incorrectly labelled as such) since first being recorded in 1816 by W.E.Leach.

Naturalists were originally puzzled over feeding methods employed by the spider as it lived in a web tube that was sealed at both ends. At one time it was thought that she broke out of her web tube and prowled the immediate area looking for food during the night time hours and re-sealed herself within to rest during the day, this is far from the truth as is explained later in this article.

Description

The female is a reasonably short legged, stocky, almost clumsy looking spider, which averages 12 - 15mm body length (although a 22mm female was recorded by the Sussex Spider Group on their field trip to Lullington Heath National Nature Reserve, June 2^nd 2007)

The female colouring is overall dark brown / black with a greenish tinge to the carapace and legs, the abdomen is often scattered with small greyish spots.

The Male, who only reaches 7 - 9mm is of a darker (almost black) appearance and is of a slimmer build.

A. affinis is recorded throughout the British Isles, but only very locally in the northern regions (only one record for Scotland), they are most common in Southern counties where they can be found in small colonies. They are usually found under cover of low vegetation where the substrate is of a sand / chalk composition. Often a web tube will be found near common black ant (Lasius flavus) mounds.

Personal observations

My first encounter was in the late 80's when holidaying in Holywell (near Eastbourne), I was walking down Beachy Head Road, quite close to the coastline playing fetch with the dog. On resting up for a while on a sandy bank, with the odd area of vegetation and "scrub", I noticed an unusually coloured beetle walking along minding it's own business, I got down close to observe and before I got comfortable the little chap was pulled struggling into the ground by "something". Closer examination lead me to find a little (4 inch) web tube, the thickness of a finger, covered in debris, sand, soil and fine gravel. My first thought was "can't be" as at that time I didn't think A. affinis was recorded in the area (later confirmed). Needless to say I found a little stick and searched for another tube.

On finding a second tube within two feet of the first, I used the stick to tease the webbing to simulate an insect, within seconds a pair of noticeably large fangs pierced the webbing and grabbed at the stick. Noticing the direction the fangs had penetrated the webbing I quickly trapped the tube behind the spider with my credit card to prevent retreat and carefully excavated the spider into a clear plastic bag (responsible dog owners always carry these) for observation.

I had no camera with me at the time, and after cursing myself started to study the little fellow. I always carried pencil and paper in my rucksack (I like to draw) so jotted down some basic sketches and notes. (Fig 1: apologies for the faded condition, it's 20 years old)

It was approx 12 mm body length, which I later confirmed was a small female. Was a more sandy brown than described in my trusty Dick Jones reference book and showed great initial aggression, repeatedly biting at the bag, later settling down nicely.

After noting and sketching I returned her to her webbing and after a short period of ascertaining her bearings she returned. That was it for the evening, one happy Colin, and one spider struck off the "to find" list.

Returning to the original tube I found that the "tear" had been repaired, I estimated that I had been studying the second find for around an hour. The prey item is, in fact, webbed to the side of the lower "bulb" and any rips or tears to the web are normally repaired before eating, giving the digestive properties of the venom more time to start breaking down the internal tissues of the prey item.

I have, since then, traveled to the majority of the distribution areas for this species, sometimes unfortunately traveling miles with no results and photographic records are minimal, but that's the way of the part time spider hunter.

I have kept a personal record with dates for the south of England, (Fig 2) I have not as yet found a specimen north of the midlands or in Wales, although on contacting Richard Gallon (BTS Journal Editor and African Theraphosid taxonomist) about this article, he informed me there was a colony less than 2km from him in North Wales, a trip for the future methinks.

From personal encounters, Riverbanks and slopes with a southerly face are preferred (most of the time I find them North side of a river facing South), with sand or chalk based ground being the favourite substrate. The tubes are about 60% underground and the uppermost portion either lies along the ground or up alongside foliage stems, having a rounded structure, Each tube end is slightly rounded and enlarged (the underground portion being the larger "Bulb") this gives Atypus room to turn around at either end when needed.

The tubes are adorned with vegetation, substrate and other little pieces of Countryside flora so as to achieve complete camouflage (I've even seen small pieces of sweet wrapper seemingly placed in the design deliberately), Due to this camouflage, finding the first one is quite hard on the senses but after the first is found you get your eye in and others come easier, normally only feet away from the first finding. I once got caught in a sharp shower when out on a field trip and thought the worst for the day, but, after the rain passed and the area started to dry off a bit I noticed that the tubes were drying out fairly quickly compared to the rest of the area, so had no rain droplets on them, and found three or four in less than a minute. In wintertime the tubes flatten and partly collapse due to the elasticity of the webbing being affected due to cold weather conditions, this coincides with the hibernation period for Atypus, normally being November to February although due to recent climate change this period is now shortening and moving gradually further on in the year. 

On excavating a vacant web tube (Fig 1, location Rushford 1989) I found remnants of food items in the lower chamber (bulb) these were recognised as beetle wing cases, fly / lacewing / wasp / bee wings, woodlice plates and brown centipede remnants. This shows the great scope of food items Atypus is able to prey upon, and you'll agree that a brown centipede (Lithobius forlicatus) is a formidable opponent for such a small spider.

Mating

Without having experienced mating first hand, I have, after some years of research, come to be very familiar with the procedure, near to the point of when eventually experiencing "the act" I'm afraid it will possibly be an anti climax.

The male, after searching in the early evening, normally around late September - early October, finds a web tube that he determines through size, structure and his own inherent taste by touch (chemotactic) senses, belongs to a female. He will beat out rhythmic communication with his front legs and pedipalps on the surface of the web tube, waiting for any signs that the female is not receptive. If the female has already been successfully mated or is immature she will give one or more sharp pulls on the web thus indicating to the male that she is not receptive and warns him to retire to find another mate.

If successful in heeding no rejection warnings he will tear an entrance in the webbing and enter (Prof. U. Gerhardt (1929) noticed in a relative species (A. muralis) that the male would deposit a drop of “saliva” on the web, which he speculated had a softening effect), after a short period of time of darting quickly through the tube the male pauses facing the female, he then presses her flat against the inner surface of the web, offering her ventral side to him, and moves forwards so he may begin mating, he positions himself so he may twist the whole tarsus around and make able the introduction of the embolus (as a peculiarity the right palp enters the right genital opening) each palp is inserted several times from 20 seconds to 20 minutes, each time a swelling of the bulb is noticeable. After mating is complete the male almost violently retracts and retreats quickly, although does not leave the web tube.

Gearhardt noticed that although the male was at risk of becoming a prey item, male and female would share the tube for several months with indifference, some males surviving the winter months and escaping alive.

The egg sac, an elongated silken bag attached to the tube in a hammock like fashion, is produced in late July to early August and contains around 100 - 150 eggs, they hatch early September and will remain in their mothers web tube until the following year, personally observed in the field to be around March to early April where they are seen emerging from a little hole in the tube showing their first instinct to climb the immediate vegetation and disperse.

Since that first evening A. affinis has been added to my "British spider obsession list" along with Dysdera crocata and Tegenaria gigantea.