Friday, June 19, 2015

Guiana Shield discoveries

I’ve spent the past five weeks sorting through ant specimens at the Smithsonian.  It’s been slow and at times tedious, but rewarding.  We’re learning a ton and making interesting discoveries.  And as of last week our photography efforts are in full swing, providing me with endless material to share here on M2M.

We now have enough species identified and photographed that we can easily appreciate the diversity found in the Guiana Shield, even within a single genus.  The turtle ants (Cephalotes species) are one such case.  These heavily armored tree-dwellers come in a variety of shapes and colors.
Turtle ants (like this Cephalotes atratus) are easily recognized by their shield-shaped heads that they use to plug up their nest entrances in stems and branches  

We collected this C. atratus from the Parabara savanna in Guyana in 2013
I collected the smaller and hairier C. pusillus in the nearby Kusad Mountains on the same expedition…

…while this C. opacus came from the upper reaches of the Palumeu River in southeastern Suriname.
My new favorite turtle ant is the flat and pinkish Cephalotes persimilis.  Instead of spines, pearly translucent ridges extend along its sides.
Cephalotes persimilis is a savanna specialist that nests in scattered trees and riverside forests surrounded by grassland.  I collected this specimen from a lone tree in the Parabara savanna.  As far as we know, the wet Amazon Basin isolates the Rupununi population of this species from the rest of its species’ range over 1,000 miles away in dry areas of southern Brazil, Paraguay and Argentina.
I collected this C. minutus at night in our camp at the foot of the Kusad Mountains…
…and this aptly-named C. spinosus at the Kuyuwini River, while waiting to catch a canoe to the Waiwai village at Parabara Landing.

All this diversity is lovely, but my favorite find so far came earlier this week.  We found the first  Guiana Shield record of the oddly-shaped Dolichoderus inpai.  This species was previously known only from the Western Amazon in Brazil, Colombia and Ecuador, but our specimen is from 1,000 miles to the east in the Kasikasima Mountains in Southeastern Suriname.  Before this week, this specimen sat unrecognized in a tiny cardboard box, known to the world only as “Dolichoderus sp. 3.”

What’s even more exciting is that no publicly accessible image of the species exists, aside from partial line drawings in an identification key.
We believe this is the first photograph, and the first Guiana Shield record, of the odd Dolichoderus inpai.

It’s been an exciting five weeks.  I can’t wait to see what the rest of the summer has to offer.

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