Signature Spider

Description:

Argiope luzona (Walckenaer, 1842). The female Signature Spider in the first picture has been in our backyard for some time now. I have been taking pictures of her whenever I noticed any interesting changes in the style of her Cruciate Stabilimentum (web decoration). I posted a spotting of this female, a few days ago, which showed what I think was the biggest web decoration I have ever seen - https://www.projectnoah.org/spottings/75... - but this spotting is more about the male A. luzona which has built its web, as you can see in my first photo, close to the web of the female. The second and third photos show greatly enlarged dorsal and ventral views of the male. I should mention, before going any further, that it is almost impossible to be certain of the gender of such a small, young Argiope luzona. There is a "rule of thumb" which says that the male's cephalothorax is always bigger than its abdomen, whereas the abdomen of the female is always bigger than its cephalothorax. That characteristic is very helpful when a young spider has grown to a length of about 4mm, but I have found it to be difficult to be sure of extremely young, very small spiders. This one is only about 2mm long. So, there is no guarantee that I am right in calling it a male. You might have noticed that there is (I think) an exuvia hanging at the top of the web decoration. This little spider will moult several times in the coming days and each time it moults, it will grow bigger. So, if it survives, it should not be too long before I know if it is indeed a male. Males, of this species, grow to a maximum size of 5mm to 6mm. Females continue growing up to maximum length of about 24mm.

Habitat:

These two spiders spiders were spotted in our backyard. Their webs were suspended on a young banana plant.

Notes:

A male Argiope spider will build a web near to that of a female and, at least in all of my observations, the male's web will be on a parallel plane, just a few inches from the female so that he is looking down at her dorsum. From there, he will observe the female until he sees that she is ready to mate. Then he will carefully approach and attempt to mate. So, the proximity and position, of this little spider, to the female is what leads me to think that it is a male. It is not uncommon to see two or three Argiope luzona (female) webs, fairly close to each other, on the same plane and side-by-side, but I have never seen a female build its web on a parallel plane, above the web of another female. I will be checking on this little spider as often as possible over the coming days and, weather permitting, I will try to get some pictures of the dismantling and rebuilding of his Discoid Stabilimentum, during the hours of darkness.