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Portia Karsch, 1878

Taxonomy

Portia spp. are found in Africa, southern Asia, and Australia where there is one species, Portia fimbriata. The genus world-wide includes more than 15 described species. Other genera belonging to the same Old World group also having Australian representatives include Cocalus, Cyrba and Mintonia (Maddison 2015). Further information on the genus in Australia can be found in Richardson and Żabka (2017) and Whyte and Anderson (2017).

Description

Portia spp. are medium to large-sized spiders, ranging in body length from 6 to 10 mm. The carapace is high, highest at the posterior lateral eyes, with a gentle slope to the rear. The head, viewed from above, is pear-shaped, widest behind the posterior lateral eyes. The posterior median eyes are half the diameter of the posterior lateral eyes and relatively much larger than those found in most other jumping spiders. The abdomen is ovate. Both the cephalothorax and the abdomen have large tufts of setae breaking up the outline of the animal, which when combined with their cryptic brown and white pattern contribute to effective camouflage.  Their camouflage and cryptic, stop-start walking helps them remain unseen when hunting other spiders. Chelicerae have five (plurident) retromarginal teeth and two or more promarginal teeth. The first pair of legs is stronger than the others, with hair tufts on the tibias. All legs have distinctive thin, elongated metatarsi and tarsi.

The male’s palp has a long, narrow embolus arising on the prolateral edge of the tegulum and forming a clockwise arc around it. The tegulum is roundish in shape without a proximal lobe. There is a distinctive flange on the posterior edge of the cymbium. The tibia of the palp has a single, short, blunt retro-lateral tibial apophysis.

The female has two large, poorly-sclerotised epigynal atria. The copulatory openings are between the atria and the epigastric fold, each one more or less centrally positioned at the posterior edge of the atria. The insemination ducts travel medially then anteriorly between the atria entering large, round spermathecae at the anterior margin.

Biology

Portia is found in a wide range of microhabitats in rainforests and woodlands of northern Australia where it hunts a range of different spiders including jumping spiders to orb-weavers. It has a broad range of adaptive behaviours and has been studied extensively by R. Jackson and his colleagues (see Richardson & Żabka, 2017 for references).

Distribution

The Australian species is known from scattered localities in Queensland and the Northern Territory. It has also been reported from India, China, Sri Lanka, Indonesia and New Guinea.

References

Davies, V.T. & Żabka, M. 1989, Illustrated keys to the genera of jumping spiders (Araneae: Salticidae) in Australia. Memoirs of the Queensland Museum 27, 189-266.

Richardson, B.J. & Żabka, M. 2017. Salticidae. Arachnida: Araneomorphae. Canberra, Australian Faunal Directory. Australian Biological Resources Study, at https://biodiversity.org.au/afd/taxa/SALTICIDAE.

Wanless, F.R. 1978. A revision of the spider genus Portia (Araneae : Salticidae). Bulletin of the British Museum (Natural History) Zoology 34, 83-124.

Whyte, R. and Anderson, G. 2017. A field guide to the spiders of Australia. Clayton: CSIRO Publishing 451pp.

* The information sheet should be read in the context of the associated diagrams and photographs. Diagrams explaining anatomical terms can be found in the ‘Salticidae’ pictures at the beginning of the list of genera.