Atrax yorkmainorum

The adult male of this spider species is reported to have an average body length between 16-17mm and average width of 7mm which includes the carapace (cephalothorax) and the abdomen, non-inclusive of legs. The dorsal groove present in the centre of the carapace is narrow and bent in a forward direction with small, fine hairs on the anterior carapace. The sternum of the average male is 4.43mm in length and oval-shaped with strong posterior hairs. Unlike spiders with long, slender legs such as the red back, Atrax yorkmainorum has wide legs averaging at 1.71mm with a length of 21.5mm. The female spider differs slightly in size, averaging at 18.84mm in body length and 7.5mm in body width. The characteristics of the dorsal groove is identical to the male species, as is the sternum (4.59mm). The average length of female spider legs is approximately 18.7mm, the first and last pair being the longest for both sexes. Each spider has a pair of venomous fangs (5mm) connected to the chelicerae on each side. Both sexes have a deep dark brown or black appearance with a shiny body and matte abdomen. Features that distinguish Atrax yorkmainorum from Atrax robustus and Atrax sutherlandi is its slightly smaller size, absence of dorsal tibial spines on its pedipalp and the sleek, curved embolus on the male, as described by Michael, R Gray

Atrax yorkmainorum is not currently widespread across Australia. The distribution of these spiders is reported to be within forest areas of south-eastern New South Wales, as well as the Australian Capital Territory according to the Australian Museum records. Common places where sightings have occurred include the alpine ash Bago State Forest and Dora Dora National park in NSW and the Uriarra Forest and Tidbinbilla Nature Reserve in ACT. The most recent recorded sighting of Atrax yorkmainorum was on the Mount Ainslie Walking Trail in ACT in late 2020. The chance of encountering a funnel web spider is increased during the humid, wet months as the male is most active in these conditions as it provides a more favourable environment. Funnel web spiders are commonly found living in sheltered habitats such as under rocks or logs.

Male and female Atrax yorkmainorum possess reproductive organs and appendages that enable successful mating and reproduction. On the distal end of the male tibia, there is a characteristic spine on the second pair of legs which assists in the mating process. According to this researcher, the presence of the spine allows the females second leg to "lock... in a raised position to enable mating and...prevent descent of the female's fangs". The mating behaviours of funnel web spiders is similar across species, with few species-specific differences. As with hunting, mating also occurs during the night in summer and spring months. After locating a female mate through pheromone sensing, the male spider will begin the mating ritual by moving in a specific way on the female spiders' silk trap-lines to generate vibrations that the female recognises as a mating signal rather than a prey alert. According to literature, the embolus of the male Atrax yorkmainorum is approximately 3mm in length with an accompanying narrow ejaculatory groove. This reproductive structure is longer in Atrax yorkmainorum species compared to the Atrax sutherlandi species (1mm difference). The embolus of the male is attached to its genital bulb, also known as the palpal organ. …