Hortophora biapicata

Fact Box Species: Hortophora biapicata (JS) (but see notes below) Previous species name: None Family: Araneidae (formerly Argiopidae) Body length: female: 20 mm male: 16 mm Habitat: In a vertical orb web at night but in a retreat above the web by day Toxicity: Uncertain; may cause mild illness but this spider is very timid and is not aggressive towards humans

The male Underneath male

Please note that the photos shown on this page are of Eriophora biapicata as described by VT Davies (Queensland Museum) in 1980 but research by Volker Framenau and others showed that some or all of them could instead be Eriophora transmarina which Davies also named. Framenau also suggested that specimens found in Northern Australia probably are Eriophora transmarina but Southern Australian ones are more likely to be Eriophora biapicata. However, in November 2021 the generic name used by Davies was changed to Hortophora by Framenau et al in Evolutionary Systematics, 5(2), pages 275-334 and these authors also described 8 other Australian Hortophora species because it was apparent that there were some 'Eriophora' species that were anatomically distinct from either of the two well known ones.

Nature notes: This kind of spider is never likely to be found inside a house or other building although it might perhaps string its web from a suitable support on an open veranda or porch. Because the entire vertical web can be constructed in a single night the householder may be surprised to find it there one morning. However, the spider itself will probably not be in evidence since the normal practice of Hortophora species is to occupy the web only at night and to hide somewhere near the upper supports of the web during the daylight hours. Until it reaches maturity the male will behave like a female but adult males will cease catching insects and will instead go in search of a web that contains a female. This search is facilitated by the detection of a pheromone secreted by the female. If it is not killed by the female during or after mating the male may search for another female but typically dies soon after reaching maturity even if it has never managed to mate. Even the adult female normally dies when the colder months of the year arrive and the supply of insects to feed on diminishes. This of course means the lifetime of a Hortophora specimen is rarely longer than 12 months but before dying the females usually lay at least one batch of eggs before dying so the species is not at risk of becoming extinct because of its short lifetime.

Known Range: Recorded as being very common in gardens and bush settings over most of Australia (though not Tasmania) but less common in Central and Northern Australia.

Spider(s) with a very similar appearance: Hortophora species, particularly Hortophora transmarina, Eriophora pustulosa and Acroaspis tuberculifera.