The distribution and nesting habits of Desis formidibalis (Araneae: Desidae), Amaurobioides africanus (Araneae: Anyphaenidae) and their associated parasitoid, Echthrodesis lamorali (Hymenoptera: Platygastridae, Scelionidae), along the South African coast Candice Owen1*, Simon van Noort2 & Julie Coetzee1 1
Department of Zoology and Entomology, Rhodes University, Grahamstown, 6140, South Africa; *
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2
Natural History Division, Iziko Museums, Cape Town, 8000, South Africa;
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2
Department of Zoology, University of Cape Town, Private Bag, Rondebosch, 7701, South Africa;
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Background The southern African coastline plays host to nine intertidal spider species. Two of these, namely Desis formidabilis O. P. Cambridge 1890 (Araneae: Desidae) and Amaurobioides africanus Hewitt 1917 (Araneae: Anyphaenidae), are recorded as hosts of an intertidal spider egg parasitoid, Echthrodesis lamorali Masner 1968 (Hymenoptera: Platygastridae: Scelioninae). The two former species are recorded from Lüderitz (Namibia) along the South African coastline to East London (Eastern Cape Province, South Africa), while the latter is currently only known from a single locality on the Cape Peninsula. Methods A transect from Jacobsbaai (Western Cape) to East London (Eastern Cape) was surveyed in an attempt to determine the full distribution of E. lamorali, as well as the nesting and breeding habits of the two spiders. Breeding status was confirmed through monthly visits to Kommetjie and Port Elizabeth sites. Results Neither of the host spiders were located north of the Kommetjie. Desis formidibalis showed differences in behaviour along the transect, with individuals east of the Peninsula choosing to nest behind encrusting organisms on more exposed shores. Amaurobioides africanus did not show much distinction in nest site choice throughout the transect. Spiders east of the Cape Peninsula also appear to exhibit breeding seasonality, while those in the Cape breed throughout the year. The parasitoid was found to be a Cape Peninsula endemic, restricted to areas where its hosts breed under empty shells or in crevices throughout the year on gently-sloped boulder-strewn shores not exposed to high wave activity. Conclusion Unlike A. africanus, D. formidabilis shows behavioural differences along the South African coastline. As the main host of E. lamorali, these differences, along with other physiological aspects of the wasp itself, appear to have an impact on the insect’s distribution, restricting it to a narrow range along the Cape Peninsula. The inclusion of this range in the Table Mountain National Park ensures the species’ effective conservation.
