Araneus marmoreus encore

Araneus marmoreus adult female—ventral view showing epigyne.

Here is the full-sized photo from which the crop shown in Super Crop Challenge #14 was taken. The small finger-like structure in the upper right of the photo—the object of the challenge—is the epigyne (or epigynum) of Araneus marmoreus (marbled orb weaver spider). Spiders have a rather unusual mating strategy—rather than possessing genitalia that couple for insemination, male spiders first form a packet of sperm (spermatophore) and transfer the packet to an enlarged segment (tarsus) at the end of their pedipalps. During mating, the male inserts the tarsus into the female genital opening, thereby effecting sperm transfer. The female genital opening and associated structures, located on the underside near the front of the abdomen, are called the epigyne and function to direct the male pedipalps during sperm transfer. The shape of the epigyne varies greatly and uniquely among species—probably serving as an isolating mechanism that prevents interspecific mating and also providing a good diagnostic character for species recognition among even very closely related species (similarly to the hardened male genitalia of many insect groups). An even closer view of the epigyne of A. marmoreus can be seen in this BugGuide photo.

Araneus marmoreus (marbled orb weaver) | Washington Co., Missouri

This is actually the second time I’ve featured A. marmoreus in a quiz—the intricate pattern of the dorsal abdomen being the subject of Super Crop Challenge #2. Folks had an easier time identifying the critter in that challenge than this one, which I guess is not surprising since people tend to know animals more by their color patterns than the structures of their genitalic openings. As in that first challenge, I encountered this adult female during a hike along the Ozark Trail, this time in Washington County in east-central Missouri. Unlike before, however, I found this spider crawling on a fallen log in the dark forest floor rather than resting in her web. The colors of this species are diverse and spectacular—a recipe that makes them almost irresistible to insect macrophotographers. That this is true is demonstrated by the 360! photos of this species posted to BugGuide.

Hot orange and yellows glow against the dark, moist wood of a fallen tree trunk.

While my previous photos of this species were colorful, these simply glow due to the more orange coloration of this individual and its contrast with the darkened color of the moist wood. It’s a November color scheme if there ever was one—appropriate since I took them exactly one year ago today on November 23, 2011. She was a lot more cooperative than the first subject, and because of this and the stable substrate on which she was sitting I was able to get my favorite shot of all—the face portrait! Not quite as endearing as a jumping spider face (with its large, anthropomorphic median eyes), but striking nevertheless.

The obligatory BitB face shot!

A word about the challenges—I’m not sure if the lack of response to this one is an indication of difficulty or further evidence of declining relevance of blogs as an interactive social medium. I can’t help but notice that blog commenting in general has dropped with the rise of more functionally interactive media such as Twitter and Google+. What do you think—was this challenge too hard, or has the concept of challenge posts lost its appeal?

Copyright © Ted C. MacRae 2012

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About Ted C. MacRae

Ted C. MacRae is a research entomologist by vocation and beetle taxonomist by avocation. Areas of expertise in the latter include worldwide jewel beetles (Buprestidae) and North American longhorned beetles (Cerambycidae). More recent work has focused on North American tiger beetles (Cicindelidae) and their distribution, ecology, and conservation.
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17 Responses to Araneus marmoreus encore

  1. Tim Eisele says:

    Well, for me it was two problems: (1) it was, indeed, a very hard challenge, and (2) this is a busy week with limited Internet access, and I never actually had time to sit down and think seriously about it.

    I’ve noticed in past years that the weeks of Thanksgiving and Christmas are by far the lowest-traffic days to my blog (generally less than half normal!), so I expect that a lot of other potential participants had the same problem.

  2. I agree with Tim. This was definitely a hard challenge and I didn’t have the time to do much research because of the holiday. However, I enjoy the tough challenges. I think it’s more fun when you don’t immediately know the answer.

    • Yep—too easy and they’re not fun; too hard and people don’t participate. I didn’t even think about the holiday (bugs always on my mind), so we’ll see what happens next time.

  3. sue says:

    I much prefer reading and commenting on blogs to tweeting. The concept of Twitter may be useful in some circumstances, but I am hard-pressed to think of any at the moment. I didn’t participate because I have no idea what the answer is. However, I really enjoy reading and learning, and you can’t go wrong with an obligatory face shot!

    • I fear those of us who prefer blog interactions to tweets are becoming cyberdinosaurs. Tweets are quick, easy, and can all be done off a single platform, and that is why it has become so popular with the majority of online types. I understand Twitter but admit to feeling a little unsatisfied by it compared to more substantive conversations on blogging platforms.

      Glad you like the face shot!

  4. Dan Mays says:

    I agree with Sue: ” I didn’t participate because I have no idea what the answer is.” – – – but that is not the point.

    The blogs that I follow are read for the joy of learning. I don’t read books because I already know what is in them. I silently read them; exactly because I do not know.

    Dan Mays
    . . . one of the silent majority

  5. For what it’s worth, the only real long-term value I can see in Twitter is its ability to provide fast-paced updates on crises, such as disasters. Otherwise, it’s largely an echo chamber or a venue for self-promotion. Blogs offer so much more opportunity for in-depth analysis or simply interesting reading. Rare is the tweet that so much as brings a smile, never mind a nugget of knowledge.

    • There seem to be different ways of using Twitter. One is the way kids use it – as group chat rooms, while another is in a sort of “provider/consumer” type of system (analagous to blogs actually). I can see how some would prefer Twitter’s “one-stop” approach for receiving links to interesting content rather than having to find it on their own, but with this comes a loss of control over what you have to choose from.

      I am both a provider and a consumer on Twitter as well as through the blog I write (provider) and those that I read (consumer). Personally, however, I don’t get near the same satisfaction from being a provider on Twitter as I do from my blog, and I’d just as soon decide for myself what content I wish to consume rather than have it fed to me. But that’s just me.

  6. just a reader says:

    Hi, I have read your entries on and off for over a year and find the topic and the information fascinating. Your writing is superb. I am grateful in many ways to have found your site.
    I prefer full sentence construction and paragraphs, etc. and so have no interest in tweeting. Also some of us are dinosaurs in that we only have desktops or laptops, and don’t have the other gadgets.
    I also agree with what everyone else wrote in the comments above, too. Keep up the good work and please know you are providing a valuable resource to those of us who like to learn. Never doubt the value of what you are doing on this blog!

  7. Pingback: Arboretum: Orbweavers and Turning Leaves » Skinny in a Land of Plenty

  8. Pingback: Spider Bytes from #SpiderMonday | spiderbytesdotorg

  9. Pingback: Araneus marmoreus, the (not so) Marbled Orb Weaver | Splendour Awaits

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