The New Guinean Horned Jumping Spiders

In general I won’t write about a new species unless I can find high-quality photographs of a live specimen or its close relatives. Today I’m relenting, because even though I could only find one available image, this is a group of spiders that begs to have something, anything, written about it. I’m talking about Udvardya, a genus of jumping spiders endemic to New Guinea. Until today, only one species was known. Now there are three (Gardzińska 2015).

The Udvardya genus is not widely recognizable, and hence has no common name. I should clarify: Udvardya had no common name until now. I am hereby pronouncing the three species as “New Guinean horned jumping spiders.” That isn’t official, I just made it up. But common names are, after all, just names people make up.

Why the name?

A preserved male Udvardya specimen (arrow added by me). Photo by Támas Szűts, licensed under CC BY-SA 3.0.

A preserved male Udvardya specimen (arrow added by me). Photo by Támas Szűts, licensed under CC BY-SA 3.0.

The arrow is pointing to a horn, and yes, that horn is on the spider’s chelicera (or fang). Only the males have these odd structures, and no one knows what they are for. They might be the result of sexual selection — generation after generation of females only mating with the “horniest” males. Perhaps they are used in courtship, to guide the female during mating, or for shoving matches between competitive males.

Many jumping spider species have males with weird-looking chelicerae, among them the ant-mimicking Myrmarachne plataleoides.

A male ant-mimicking jumping spider. Photo by Jeevan Jose, licensed under CC BY-SA 4.0.

A male ant-mimicking jumping spider. Photo by Jeevan Jose, licensed under CC BY-SA 4.0.

At first glance, giant fangs might seem like an adaptation to eating giant prey, but both males and females of this species eat ants. Instead the males use their fangs as tusks in sparring matches with rivals, battling over females in the treetops (Pollard 2009). In fact, the male’s fangs are so specialized for this purpose that they no longer have the ability to inject venom. The female, content with practicality, has perfectly normal-sized, venom-injecting fangs.

The female Myrmarachne plataleoides. Photo by Photo by Sean Hoyland, in public domain.

The female Myrmarachne plataleoides. Photo by Sean Hoyland, in public domain.

Might the male New Guinean horned jumping spider use his fangs to fight off other males? Perhaps. The truth is, we have no idea what the horns are used for because the only spiders ever to be studied have been dead specimens, preserved in vials of ethanol. To this day, 100 years after their discovery (Szombathy 1915), nothing is known about the behavior of horned jumping spiders, just as virtually nothing is known of their role in New Guinean ecosystems. We can at least guess that they are predatory, but that’s about as far as speculation takes us.

Sadly, our questions may never be answered: about 1.4% of Papua New Guinea’s rain forest is destroyed each year (Shearman et al. 2008). Between 70% and 90% of this is cut for timber, with the rest burnt to make way for farmland. Incidentally, New Guinea is home to around 5% of all known species on the planet, and many of these are found nowhere else.

Highland habitat in New Guinea. Photo from eGuide Travel, licensed under CC BY 2.0.

Highland habitat in New Guinea. Photo from eGuide Travel, licensed under CC BY 2.0.

I chose to write today’s article on Udvardya for a reason — not just because I like obscure creatures (although I do), and not because jumping spiders are amazing (even though they are). I wrote about New Guinean horned jumping spiders for the same reason that I wrote about ciliate protozoans instead of tarantulas, and Antarctic polychaetes instead of lizards, even though lizards and tarantulas undoubtedly have more “charisma.” Some of our planet’s most amazing species are also some of the most poorly-known. Many of them have only been studied in museums, and most have never been photographed while alive, if at all.

It is a tremendous privilege to live, work, and grow in a world where there are such things not only as elephants, tigers, and trees but also as ribbon worms, millipedes, and even spiders. Nothing about the laws of nature dictated that jumping spiders had to evolve, but by an incredible stroke of luck, they did, and we are here to appreciate them. What lucky creatures we are!

Cited:

Gardzińska J. 2015. Revision of Tarodes Pocock, 1899 and Udvardya Prószyński, 1992 (Araneae: Salticidae), with descriptions of two new species of Udvardya from New Guinea. Zootaxa 4039 (3): 445–455.

Pollard S.D. 2009. Consequences of sexual selection on feeding in male jumping spiders (Araneae: Salticidae). Journal of Zoology 234(2): 203-208.

Shearman P.L., J.E. Bryan, J. Ash, P. Hunnam, B. Mackey, and B. Lokes. 2008. The State of the Forests of Papua New Guinea: Mapping the extent and condition of forest cover and measuring the drivers of forest change in the period 1972-2002. University of Papua New Guinea, 2008.

Szombathy C. 1915. Attides nouveaux appartenant aux collections du Musée national hongrois. Annales Historico-Naturales Musei Nationalis Hungarici 13: 468-490.

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3 Responses to The New Guinean Horned Jumping Spiders

  1. Sean McCann says:

    My guess is they use them during copulation to hold the female’s chelocerae, much like some tetragnathids do. Very interesting!

    Like

    • That does seem more likely than male-to-male combat. The horns don’t really look built for fighting. Both males and females also have very long front legs, but I don’t know enough about jumping spiders to know if that conveys any useful information.

      Liked by 1 person

  2. Pingback: Spiderday (#21) | Arthropod Ecology

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