Pholcid eggs and egg-sacs
Published in Invertebrate Biology, 2021,

Published data on egg sizes and egg numbers in Pholcidae have been mostly anecdotal, like in other spider families. Here we attempt a comprehensive compilation of egg size and clutch size data in pholcid spiders. Three aspects combine to make pholcid spiders an ideal group for such a compilation of data. First, pholcid egg-sacs are usually ‘covered’ by a few turns of silk only, allowing precise egg measurements without manipulating the egg-sacs. This is in contrast to many other spider families where a dense layer of silk impedes a direct view of the eggs. Second, pholcids carry their egg-sacs with their chelicerae. As a result, a photo showing a female with her egg-sac combines data on body size, egg size, and egg number. And third, my database (partly accessible here) contains thousands of photos showing females with egg-sacs. Females (and in many cases egg-sacs) originating from the same localities as the photographed females are available in all cases, allowing a transformation of screen (photo) measurements to real values.

We found the expected strong effects of female body size and egg size and number, but also some unexpected effects such as an effect of body shape. Here some examples. Dark points and line symbolize species with long abdomen, light grey points species with short abdomen.

Some female pholcids and their egg sacs. A. Belisana sp. (“Mal3”), Singapore. B. Calapnita nunezae, Philippines. C. Carapoia alagoas, Brazil. D. Carapoia agilis, Brazil. E. Mecolaesthus cornutus, Venezuela. F. Litoporus curimagua, Venezuela. G. Ninetis(?) sp. (“Om84”), Oman. H. Metagonia reederi, Galapagos. I. Guaranita goloboffi (ventral view), Argentina. J. Metagonia latigo, Venezuela. K. Uthina luzonica, Malaysia.