The Find-a-spider Guide - Propostira quadrangulata?

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Propostira quadrangulata?

Fact Box

Species:

Propostira quadrangulata?
(The spider presented on this page was previously misidentified by Ramon Mascord as a Corinnomma species - see notes below)

Family:

Theridiidae
(was thought to be Clubionidae by Ramon Mascord)

Body length:

female: about 7 mm
male: 3-5 mm

Habitat:

Being an obvious ant mimic this spider is a rainforest species that tends to wander on tree trunks among streams of green tree-ants on which it feeds

Toxicity:

Unknown but probably harmless to humans


Male eye pattern	Underneath male	Another view	Female, side view
Female from above	Underneath female	Female eye pattern	with its egg sac

The generic name of this spider is uncertain. Ramon Mascord presented it as a Corinnomma species belonging to the Family Clubionidae and in her 2001 book "Forest Spiders of South East Asia" (ISBN: 90-04-11959-0) C. L. Deeleman-Reinhold included drawings of several Asian Corinnomma species that have overall body shapes much the same as those of the spider featured on this page. The eye arrangement is almost identical and even the adult male palp is at least superficially similar.

On the other hand, the appearance of this spider is not incompatible with the possibility that it is a theridiid though unfortunately none of the photos show Leg IV well enough for the presence or absence of a tarsal comb (a characteristic of the majority of the Theridiidae) to be ascertained. The fact that the spider makes a spherical egg sac also suggests it is a theridiid, corinnid and clubionid females generally constructing a pillow-like egg sac.

Professor V.K. Patil at the Wildlife Institute of India, Dehradun, has now suggested that Mascord's Corinnomma is actually a Propostira species, two of which are known to be present in India and Sri Lanka. Dr. Robert Raven (Queensland Museum) agrees that the spider shown on this page is indeed very much like the theridiid genus Propostira as originally described by Simon. He suggests that while no Australian Propostira species have been formally described so far it is quite possible that the range of this genus extends from India to Australia and that Mascord's Corinnomma is definitely a theridiid and should be provisionally shown as a Propostira species. The quadrangulata species name is assumed since this is the species name for an Indian spider (for which no photos are present on the internet) that has not been formally declared to be present in Australia. However, the fact that the four black false eyes on the abdomen form a quadrangle makes it very likely that the spider presented on this page is indeed Propostira quadrangulata.

This spider and the thomisid, Amyciaea albomaculata, have a quite similar appearance, presumably because they are both attempting to mimic the same green tree-ant species. The most useful visible differences between these two spiders are that Amyciaea has large lateral eyes whereas the eyes of the spider presented on this page are all relatively small and there are only two black false eyes on the abdomen of Amyciaea but four protrusions on the Propostira abdomen.

Known range: Assuming it really is present in Australia this species is likely to be found only in Northern Australia.

Email Ron Atkinson for more information. Last updated 20 January 2022.