Answer to Super Crop Challenge #1

Seemingly correct answers came quickly to yesterday’s inaugural Super Crop Challenge, which featured a curious structure atop a harvestman (class Arachnida, order Opiliones) that I encountered while hiking the lower North Fork Section of the Ozark Trail in extreme southern Missouri. “Seemingly” I say, because even though some points were earned, others remained left on the table – the organism was rightly recognized as a harvestman, and the structure in the photo does indeed contain the ocelli (or eyes).  However, nobody actually named the structure itself (see update below) – the ocularium (ocular or optical tubercle would also have been accepted).  Hey, I’m pedantic and proud!

As near as I can tell, this individual belongs to the genus Leiobunum (family Sclerosomatidae).  Species in this genus are notoriously difficult to identify; however, the super long legs, dark dorsal stripe, pointed abdomen, and very long palps with “knees” that extend dorsally to a level well above the ocularium suggest a male L. vittatum or one of its close relatives (Schulz 2010). Leiobunum vittatum is a common inhabitant of wooded habitats across the eastern U.S.

I took this shot with an MP-E 65mm macro lens at about 2.5X. The short working distance of the lens at this level of magnification makes it difficult to photograph these longer-legged species in lateral profile due to their habit of “waving” their especially elongate 2nd pair of legs in the air as pseudo-antennae – one touch of any part of the camera sends them scampering. I chased this guy back and forth across a downed tree trunk for some time before I finally got lucky when it encountered some prey (note the long structure extending down from the mouth area – I believe it is the antenna of a tiny, nymphal blattodean) and became distracted just long enough for me to close in and fire off a couple of close shots. He was actually closer to the underside of the log, so when I took this photo I was leaning far over the log with the camera almost upside-down!

Okay – Art earns points for being the first to identify it as a harvestman, while Geek snaps rare duplicate ID points for using the order’s scientific name (no complaining – scientific names will always get points on this blog).  Art, Aniruddha, and Geek also get half-points for mentioning (in order of correctness) eye, ocelli (technically more correct, but wrong plurality), and ocellus (yes, only one is visible – did I mention my pedantic tendencies?).  However, I’m going to declare arachnologist and Opiliones specialist Chris as the winner of this round for his impressive display of generic-level identification based on the meagerest of evidence!

Update 11/22, 11:00 a.m. – actually, Chris did name this structure in an email sent to my office address while the comments box was unchecked and, thus, earns a clean sweep of this challenge.

Photo Details: Canon 50D w/ MP-E 65mm 1-5X macro lens (ISO 100, 1/250 sec, f/13), Canon MT-24EX flash w/ Sto-Fen + GFPuffer diffusers. Typical post-processing (levels, minor cropping, unsharp mask).

REFERENCE:

Schulz, J. W. 2010. The Harvestmen of Maryland (accessed 20 November 2010).

Copyright © Ted C. MacRae 2010

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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19 Responses to Answer to Super Crop Challenge #1

  1. Their legs do get in the way, don’t they? I have tried approaching them from the top for a dorsal view, but your excellent profile accentuates the eyes so much better.

  2. James C. Trager says:

    I really wanted the cropped structure to be from a larval cicindelid, but couldn’t force it into that ID.
    Looking forward to more of these…

  3. david winter says:

    You call those long palps? As Chris would be able to tell you, we do long palps properly down in New Zealand:

    Megalopsalis fabulosa
    (I think it’s actually the chelicerae that are super-massive in those guys)

  4. Okay, we’ve seen some crazy palps and some crazy chelicerae – are there any opiliones that have crazy both?!

  5. Jeff Shultz says:

    Hi, Stumbled on your site and saw your great harvestman picture. The animal is a male Leiobunum crassipalpe, a close relative of L. vittatum that ranges from southern Missour, northern Arkansas and eastern Oklahoma.

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