Tree-Stem Trapdoor Spider (Aganippe castellum) - Wheatbelt NRM

More documents

Recommendations

Info

2. TREE-STEM TRAPDOOR SPIDER ECOLOGY AND LIFE HISTORY2.1 History and Taxonomic RelationshipsThe Tree-Stem Trapdoor Spider, (Aganippe castellum) was first identified by BarbaraMain in 1986. The species name castellum is translated from Latin to mean ‘fortress’or ‘tower’, describing the above-ground burrow structure which distinguishes thisspecies from other trapdoor spider species.Any cross-breeding with other spider species is unknown, but thought to be unlikelydue to the morphological distinction of this species and the short dispersal distance ofoffspring from the parent burrow.2.2 DescriptionA. castellum is a medium-sized spider, dark brown to black in colour, and has largeanterior lateral eyes that project beyond the edge of the carapace (Burbidge, 2004).The length of the carapace ranges from 6.8-8.8mm and the width ranges from 5.2-6.2mm (Main, 1986).Females are distinguished by thorn-like spinules which cover the labium, sternum,anterior edge of the carapace, membranous margin of the carapace and are also foundin the foveal crevice (Figure 1). The abdomen is hirsute and the internal genitaliabroad-based. Males have marginal spines on the carapace, the tarsi lack spines, andthe palpal tarsus possesses about six apical spines. The embolus has a narrow flangeand sharp, subterminal ventral projection, with dorsal spines on the abdomen (Main,1986).2.3 Distribution, Habitat and MovementsThere are currently 22 known populations of A. castellum which have an extent ofoccurrence of approximately 25,000 km 2 (determined by enclosing knownpopulations in a spatial polygon). The area of occupancy is likely to be considerablysmaller due to the short dispersal distances of offspring. It is thought that eachpopulation occupies no more than 1 km 2 and has an abundance ranging from 6 to 190individuals (Russell, 2006).4
Figure 1: Photograph of a female Tree-stem trapdoor spider. (Photo: Monica Russell)The 22 known populations of A. castellum occur in the south-west of WesternAustralia. They extend to the north as far north as Pintharuka Nature Reserve(Morawa Shire), south to the Merredin townsite, and east to Southern Cross (Figure2). The population at Pintharuka is the only known population that exists outside ofthe Avon Catchment Council (ACC) NRM (Natural Resource Management)Boundary. Details regarding the location, tenure, population size and date of lastonsite monitoring etc for each known population are included in Appendix 1.A. castellum prefer habitats in flood-prone depressions and flats that supportmyrtaceous shrub communities. The burrows of this species are specially designedwith an aboveground entrance to withstand occasional sheet flooding (Main, 1987a).2.4 Biology and EcologyA. castellum live in individual nests throughout their entire lives. The nests structureof A. castellum is unique to this particular species. These spiders generally build theirnests against the stems of trees such as broombush (Melaleuca uncinata), Sheoaks(such as Allocasuarina acutivalvis) and other Myrtaceous shrubs in sandy loam soils(Freegard, 2003).5
Page 1: AVON SPECIES CONSERVATION PLANTREE-
Page 4 and 5: 13. SUMMARY OF CONSERVATION ACTIONS
Page 6 and 7: Conservation plan objective:To main
Page 10 and 11: The silk lining of the burrow exten
Page 12 and 13: 3. HABITAT CRITICAL TO SURVIVALHabi
Page 14 and 15: DEC also provides advice to the Com
Page 16 and 17: Grazing by rabbits causes a reducti
Page 18 and 19: 7. AFFECTED PARTIESThe main parties
Page 20 and 21: 11. CONSERVATION OBJECTIVES AND CRI
Page 22 and 23: 12.2 Determine the population chara
Page 24 and 25: Completion date: On - goingCost:$1,
Page 26 and 27: 13.0 SUMMARY OF CONSERVATION ACTION
Page 28 and 29: Appendix 1: Summary of A. castellum

Tree-Stem Trapdoor Spider (Aganippe castellum) - Wheatbelt NRM

Create successful ePaper yourself

Delete template?

Save as template?