Friday Fellow: Black-Tailed Red Sheetweaver

by Piter Kehoma Boll

There are many spider groups that are well-known by the general public: tarantulas, jumping spiders, wolf spiders, orbweavers… but one of the groups with a very large number of species, the family Linyphiidae, is usually unnoticed.

Spiders of the family Linyphiidae are commonly known as sheetweavers because of the shape of their webs. A common species in the eastern United States, especially in the southeast, is Florinda coccinea, known as the black-tailed red sheetweaver or red grass spider. Being only 3 to 4 mm long, the black-tailed red sheetweaver has a red body with a small black tip on the abdomen. The legs are reddish-brown to black.

Female black-tailed red sheetweaver in Mississipi, USA. Photo by Tiffany Stone.*

Males and females are very similar in size, with males being slightly smaller. They can be easily distinguished by the abdomen and the pedipalps as in most spiders. Females have smaller pedipalps and a rounder abdomen, while males have larger pedipalps with a round expansion at the tip and slenderer abdomens.

A male in Florida, USA. Photo by iNaturalist user rsnyder11.*

The web of the black-tailed red sheetweaver, just like in other sheetweavers, consists of an horizontal sheet over which some additional threads above. Flying insects, when they colide with the threads, fall on the sheet and are captured by the spider.

Typical aspect of the black-tailed red sheetweaver’s web as seen in the field, here covered by dew droplets. Photo by iNaturalist user ndrobinson.**

The mating behavior of the black-tailed red sheetweaver begings with the male entering the female’s web. He usually cuts off part of the female’s web and deposits new web at the same place. After this, he approaches the female, touches all her legs with his two anterior pairs of legs, and then start the pseudopulation, in which he introduces the tubes of his palps into the female genitalia but, as they are still empty, fertilization cannot occur. After some time playing like this, the male builds a small triangular web sheet and deposits a drop of sperm on it. He then collects the sperm with his pedipalps and approaches the female once more, this time breeding her for sure.

Again, the ecology and life-history of the black-tailed red sheetweaver is not very well studied. And the same is true for almost all species in the family Linyphiidae, even though it is the second largest spider family on the planet. They are too tiny for most of us to care.

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References:

Robertson MW, Adler PH (1994) Mating behavior of Florinda coccinea (Hentz) (Araneae: Linyphiidae). Journal of Insect Behavior 7(3): 313–326. doi: 10.1007/BF01989738

Wikipedia. Blacktailed red sheetweaver. Available at < https://en.wikipedia.org/wiki/Blacktailed_red_sheetweaver >. Access on October 23, 2019.

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*Creative Commons License This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.

**Creative Commons License This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.

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Filed under Arachnids, Friday Fellow, Spiders

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