Taxonomy

Ocrisiona has nine Australian species, Ocrisiona aerata, O. eucalypti, O. koahi, O. leucocomis, O. melancholica, O. melanopyga, O. parmeliae, O. victoriae and O. yakatunya. A further species, Ocrisiona parallelestriata, is considered misplaced. The genus is part of an Australasian clade (Maddison et al 2008) related to Abracadabrella, Apricia, Clynotis, Holoplatys, Huntiglennia, Opisthoncus, Paraphilaeus, Paraplatoides, Pungalina, Tara, Trite and Zebraplatys (Maddison 2015). Several very poorly known genera from New Caledonia (e.g. Corambis, Lystrocteisa and Penionomus), may also be part of this group. Further information on the genus and described species can be found in Richardson and Żabka (2017) and Whyte and Anderson (2017).

Description

Ocrisiona includes large spiders, ranging in body lengths from 10 to 15 mm. The head, viewed from above, is pear-shaped, widest well behind the posterior lateral eyes. The cephalothorax is low and flat, the abdomen elongate-ovate. Chelicerae have a single (unident) retromarginal tooth and two promarginal teeth. The first and fourth legs are longest, the second pair of legs next longest. The third pair of legs is much shorter. The spines on the first and second tibia are vestigial, otherwise spines are absent. Superficially, Ocrisiona spp. can be almost indistinguishable from some Holoplatys spp. The palp morphology differs, but for those without access to genitalia, there is another useful difference; the absence of a small pit on the medial side of each of the posterior lateral eyes in Ocrisiona but present in Holoplatys.

The male’s palp has a long embolus forming an anticlockwise curve arising on the distal edge of the tegulum. The tegulum is almost as wide as it is long, without a proximal lobe. The palpal tibia has a very short, blunt, partially-bifurcated retro-lateral tibial apophysis.

The female has two large, deep, epigynal atria joined in the middle by a narrow ridge. Spermathecae, located on the lateral edges of the atria, can be easily seen through the surface. The copulatory openings are at the most anterior points of the atria and surrounded by small sclerotised guides. The long insemination ducts travel posteriorly to join the anterior margins of the spermathecae. Spermathecae are pear-shaped with well-developed diverticulae located under the posterior margins of the atria, at some distance from the epigastric fold.

Biology

Ocrisiona spp. are found under bark on tree trunks but also in litter and lichen in forests, woodlands and heathlands.

Distribution

Ocrisiona has been collected across all Australia including Tasmania, Lord Howe Island, Norfolk Island and Phillip Island, so far not reported from Australia’s far north-western parts.

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.

Maddison, W.P. 2015. A phylogenetic classification of jumping spiders (Araneae: Salticidae). Journal of Arachnology 43, 231-292.

Maddison, W.P., Bodner, M.R. & Needham, K.M. 2008. Salticid spider phylogeny revisited, with the discovery of a large Australian clade (Araneae: Salticidae). Zootaxa 1893, 49-64.

Richardson, B.J. & Żabka, M. 2016. Salticidae. Arachnida: Araneomorphae. Canberra, Australian Faunal Directory. Australian Biological Resources Study, at https://biodiversity.org.au/afd/taxa/SALTICIDAE.

Whyte, R. & Anderson, G. 2017. A Field Guide to Spiders of Australia. CSIRO Publishing: Clayton.

Zabka, M. 1990. Salticidae (Araneae) of Oriental, Australian and Pacific Regions, IV. Genus Ocrisiona Simon, 1901. Records of the Australian Museum 42, 27-43.

* The information sheet should be interpreted 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.