Comparison Chart | Eli M. Sarnat

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Commonly intercepted attines

March 9, 2012 Eli Sarnat No comments

Of the records I’ve seen, three attine species appear most frequently on port intercept lists: Acromyrmex octospinosus, Atta cephalotes, and Atta sexdens. I’ve had difficulty finding publications or even online resources detailing characters separating the minor worker caste of these latter two Atta species. I’ve drawn up a few preliminary characters myself, based on Antweb images and a few specimens of each I borrowed from Phil Ward, but would like to get them confirmed by folks more familiar with these taxa.

Can anyone out there who knows the attines give a thumbs up or down to the last two characters in this chart?

	Atta cephalotes	Atta sexdens	Acromyrmex octospinosus
profile
head
pairs of spines on promesonotum	Two	Two	Three
gaster with tubercles	No	No	Yes
head of soldier covered in long fine overlapping hairs giving a woolly appearance	Yes	No
head covered in hexagonal microsculpture giving it a dull appearance	No (smooth & shiny)	Yes
cephalic dorsum with two small teeth anterior to posteriorly projecting spines (UNVERIFIED)	No	Yes
pronotal spines strongly arching anteriorly (UNVERIFIED)	Yes	No

Comparison Chart, Intercepted Ants Acromyrmex octospinosus, Atta cephalotes, Atta sexdens, comparison chart

Introduced Nylanderia of the United States

March 1, 2012 Eli Sarnat No comments

I’ve spent the last couple of days parsing the differences among the many introduced species of Nylanderia. I still haven’t gotten a good look at the Rasperry Crazy Ant or Caribbean Crazy Ant or the Hairy Crazy Ant or whatever folks are calling the species that has been spreading across the southeastern United States, but apparently it is close to N. fulva and N. pubens. Hopefully John LaPolla’s revision of the Nearctic Nylanderia will be out soon, and I’ll be able to update my provincial key characters.

In the meantime, here’s a link to an illustrated comparison chart of Nylanderia introduced to the United States (including Hawaii).

And here’s a gallery of the various illustrations I’ve put together thus far for the key.

[Show as slideshow]

Selected references and resources of introduced Nylanderia species. (Note that all these species of Nylanderia were treated as Paratrechina prior to LaPolla et al. (2010)).

Trager, J.C. (1984) A revision of the genus Paratrechina (Hymenoptera: Formicidae) of the continental United States. Sociobiology, 9, 49-162. [Includes keys and descriptions of N. bourbonica, N. flavipes, N. guatemalensis, N. fulva, N. vividula all in addition to the native species].

LaPolla, J. S.; Hawkes, P. G.; Fisher, B. L. 2011. Monograph of Nylanderia (Hymenoptera: Formicidae) of the World, Part I: Nylanderia in the Afrotropics. Zootaxa 3110:10-36. [PDF] [Covers three spp. of Nylanderia purportedly introduced to the Afrotropics, including N. bourbonica, N. vaga and N. vividula.]

LaPolla, J.S., Brady, S.G. & Shattuck, S.O. (2010) Phylogeny and taxonomy of the Prenolepis genus-group of ants (Hymenoptera: Formicidae). Syst. Entomol., 35, 118-131. [PDF]

Ivanov, K. & Milligan, J. (2006) Paratrechina flavipes (Smith) (Hymenoptera: Formicidae), a new exotic ant for Ohio. Proc. Entomol. Soc. Washington, 110, 439-444. [Nice small paper on N. flavipes and how to distinguish it from N. vividula.]

Ants of the Southeastern United States – key to species of Nylanderia. [Excellent website of Joe MacGown with a key adapted from Trager (1984).]

Comparison Chart, Illustrations, Introduced Ants comparison chart, illustrations, introduced ants, Nylanderia bourbonica, Nylanderia flavipes, Nylanderia fulva, Nylanderia guatemalensis, Nylanderia vaga, Nylanderia vividula

Trampy Linepithema

February 13, 2012 Eli Sarnat No comments

As I am developing the new update to my Lucid key to invasive ants, I realized it might be a good idea to post some of the illustrations I’m working on as little vignettes of the larger project. When I’m not quite sure about an ant ID, I find myself using the ‘comparison chart’ tab on PIAkey more often than the actual Lucid key. It’s like a quick-access cheat sheet for when you already know the genus and just need a little refresher for distinguishing among a few species.

This chart shows how to tell the very commonly encountered Argentine ant (Linepithema humile) from its less well known, but occasionally intercepted congener L. iniquum. The characters are adapted from Alex Wild’s treatise of the genus (Wild, 2007).

	*L. humile*	*L. iniquum*
Profile
Erect hairs on cephalic dorsum (above eye level) + gastral tergites 1 & 2	No	Yes
Dense pubescence covering mesopleura	Yes	No
number of convexities on profile of mesosomal dorsum	Two	Yes
propodeal shape	Angular	Globular
propodeal spiracle bordering posterior margin of propodeal profile	Yes	No