Spiders of the genus Latrodectus, along with tarantulas and jumping spiders, are probably the best known spiders in the world. They are commonly referred to as button spiders in South Africa, redback spiders in Australia, katipo in New Zealand, or widow spiders elsewhere. We at WTF Entomology, part of Wild Tomorrow Fund, are proud to announce our recent discovery of a new forest dwelling widow species which we have called the Phinda button spider. Although a scientific name has been chosen, we will only release it once the species description has been published, which is currently under review. NOTE: This blog is quite long and has been purposely written this way for anyone who wants to understand the process we went through.
Because the spider is a South African species, we will refer to it as a button spider instead of the more famous black widow moniker. The Phinda button spider is one of the largest button spiders in the world (if not the largest), and definitely larger than any of the other African species. They live specifically in a critically endangered forest type called sand forest which is unique to South Africa and southern Mozambique.
In February 2014 we got a phone call from Naomi Schutte, the wife of Tembe Elephant Park (Tembe) manager Richard Schutte. We had asked them to let us know if they saw anything interesting that crawls on 6 or 8 legs. Naomi had found a cool looking spider in the hollow of a tree in her garden. We rushed to see it first thing in the morning. This is how the first specimen was discovered in Tembe. My husband Clinton Wright and I had been living and working in Tembe at the time. We believed it to be a new species, but it was difficult to prove with just a single specimen. We observed and monitored the spider for over 2 years until she died of old age, then we collected her and sent her to a University for identification.
Button spiders can be difficult to identify, and with only a single specimen, it was initially thought to be the first record for a Zimbabwe button spider in KwaZulu-Natal. However we felt that this was not the correct identification and we then embarked on a journey of discovery that led us by chance to finally discover more specimens and describe this new and incredible button spider.
What stood out for us was the fact that the Tembe specimen had laid 3 (infertile) egg sacs that were bright purple. We could find no other button spider around the world that had a similar coloured egg sac. However, variations and anomalies do occur in nature and until we had more information, it was simply just a belief without proof.
Taxonomists in the entomology and arachnology world are a rare breed – and with so many species still being described - it was hard to find answers. We searched online and posted on social media but didn’t get any satisfactory responses. Slowly over time the spider became more of an afterthought and on the back burner. This all changed one day when Dr Ian Engelbrecht, a good friend and arachnid specialist, came to visit to do some scorpion work on our property Ukuwela, which borders on Phinda Private Game Reserve. When Ian arrived we went through our now familiar routine of showing various captures and specimens of interest, and ended as always with the showstopper, the button spider. Ian took one look at it and exclaimed, “Oh My God – that’s a new species”. Finally, to have someone with extensive knowledge to recognise and confirm what we had always believed. This still didn’t help us as we no longer had the specimen (it was sitting in a jar at a university) and we had no idea where to start.
We had booked a spider walk that week with Ryan Tippet in the sand forest of Phinda. We decided to show Ryan the pictures and ask him if he had seen anything similar in his spider walks in the region. As luck would have it, he had seen exactly this species on his last spider walk in Phinda, spotted by Tamsin Naylor, during a spider walk, and they knew exactly where she was. The next few days were some frantic phone calls and arrangements being made with Simon Naylor, the manager of Phinda, which ultimately led us to collecting 2 wild females and one egg sac. This was almost 4 years after the discovery of the first specimen. Phinda’s Ecologist, Craig Sholto-Douglas, then led us through many nights of searching and observing these spiders in the wild and she slowly became the star she was always meant to be. Robin Lyle, Luke Verburgt and Catherine Sole all joined our amazing journey and helped us further unravel the mysteries surrounding the Phinda button spider, each contributing in their unique way.
Before this discovery, there were 31 recognised species globally, with eight recorded from the African continent. Of these eight, six are endemic to Africa (Latrodectus cinctus, L. indistinctus, L. karrooensis, L. renivulvatus, and L. rhodesiensis), and all occur in Southern Africa. The brown button spider (L. geometricus) is believed to have originated from Africa or South America, and has been introduced to North America, parts of Europe, parts of Asia, and parts of Australasia. It is common in parts of southern Africa and is considered cosmopolitan. L. pallidus occurs from the Cape Verde Islands to Libya and L. tredecimguttatus from the Mediterranean to China. Both L. pallidus and L. tredecimguttatus are absent from sub-Saharan Africa. This, in the arachniverse, was a big discovery.
We spent the next year raising and feeding thousands of spiders. My young son Ricky was roped in to help find wild food (aphids, ants and fruit flies when small; termites and anything else as they grew larger) and raise the spiderlings. We raised the spiderlings from the two wild egg sacs with the aim of collecting a male as we have to this day never seen a male in the wild, and at the time had no idea what they looked like. The two wild caught specimens thrived in captivity under conditions mimicking their natural habitat, and they produced another 10 egg sacs in total while in captivity.
As each egg sac on average has about 584 spiderlings (471-692; n=4), this roughly translates to over 6400 spiderlings we raised in a very short time. Most of these we released back into their original habitat, while some we collected for DNA work and fecundity estimates. The purple egg sac is quite large and smooth, bright purple when fist constructed and fades over time to a silvery grey colour. We also noticed that when the egg sac wasn’t fertile, it remained a round shape, but when fertile, formed a tear drop shape, likely due to the weight as it hangs in the web. The spiderlings emerge around 29.9 (27-36; n=9) days after being laid and sometimes stay in the egg sac a few days before emerging, possibly waiting for ideal conditions. They are tiny and brown, with unique white markings. These markings remain the same throughout their life in both sexes, although change in colour and clarity.
In searching for a male, our first attempt yielded poor results as we left the spiderlings together for about a month, feeding them on aphids and fruit flies. This is when we noticed quite a bit of cannibalism, which urged us to separate them from each other. We randomly selected spiderlings and housed them alone to wait for signs of a male. There were very few males in this batch. The next egg sac we separated spiderlings randomly immediately after emerging, and there was a much higher ratio of males to females. It is possible that the females in the first group had targeted males when they started to grow, although this wasn’t tested and just noted for interest.
Males (in captivity) could be identified after about 15-20 days by their uniquely shaped pedipalps and were mature around 26 days. Once mature they stopped shedding and stopped eating and their colours slowly darken over time until it appears to be a uniform dark brown, but under light it still has the same general patterns as all specimens. Mature male abdominal colouration changes dramatically as it ages and fades. The colour of the abdomen of a young mature male is brown with light yellow-white oblong blotches dorsal median and laterally (with indistinct dark brown outlines), and no transverse light areas. Old mature males have a dark brown abdomen with darker brown irregular circle shapes (the same pattern and position) visible under bright light or flash photography.
In females the dorsal median and ventral markings turn yellow with white outline and overall brown colour darkens, until black and reaches maturity after ca. 6 months. Legs are initially banded, but turn uniform black in females when mature. General abdominal shapes, patterns, and positions thereof, remain relatively constant across males, females, and individuals and throughout their lifecycle, changing only in colour and clarity.
While we collected crucial observation data on the new button spider, my husband and I researched all Latrodectus species across the world for comparison. Just because this spider is new to the region or country, it doesn’t mean it couldn’t have blown in or somehow made it across from, for example, Madagascar. We had to eliminate the possibility that these were already known to science. Button spiders are difficult to describe as there is no single attribute one can use to separate the species with confidence. Initially, colour patterns and characteristics of the abdominal setae where used to distinguish between species until Levi (1959) concluded that this was insufficient and recommended using genital morphology instead. Lotz (1994) suggested that the two methods should be used in combination to address the morphological overlap in certain species.
In the African species there are generally two “groupings” accepted and described by Lotz (1994). These are the (1) the geometricus species-group (L. rhodesiensis; L. geometricus) and (2) the tredecimguttatus species-group (L. tredecimguttatus; Latrodectus cinctus; L. indistinctus; L. karrooensis; L. renivulvatus; L. pallidus). These two groupings are more commonly referred to as Brown Button Spiders and Black Button Spiders respectively, although we don’t personally like using these “colour” terms. The Phinda button spider genetically is closest to the L. geometricus group, although visually resembles most closely certain members of the L. tredecimguttatus group. The Phinda button spider can be diagnosed from the other African species by the presence of both a distinct red marking on the ventral surface of the abdomen and a red stripe on the posterior dorsal surface of the abdomen. This species appears to be unique in that it produces a large egg case which is purple in colour when first produced, progressively fading to grey before the spiderlings emerge, while other African species either have a small white spikey egg sac or a large smooth or woolly white egg sac.
Mature males of the Phinda button spider are generally similar to or slightly smaller than other African species. The males can be diagnosed from other African species by having a yellow-white ventral marking anterior to the spinnerets and a yellow-white transverse ventral marking near the book lungs.
We then had to separate this species from all other Latrodectus species worldwide. This was quite an arduous task as some recognised species have very little information recorded and the genus as a whole needs to be revised. However, through persistence and gaining access to type specimens when possible, we were able to eliminate all previously described species. We were able to conclude that this was indeed a new species.
Almost all the specimens found in the wild were in tree hollows higher than 80cm off the ground. The one exception was found at 50cm above the ground. This differs from other African species as their refuges tend to be much closer to the ground.
This entire process has consumed our daily lives for a while now, but with the publication imminent, it will seem strange to move on to the next discovery. Finding something as unique and special as the Phinda button spider simply showcases the possibilities of what might still be out there waiting to be found. I hope that the next scientist, amateur arachnologist or arthropod-crazy hobbyist can get to experience the same joy we did in finding the Phinda button spider.