Morphometric measurements from vector images

I’ve been trying to find a good method for quantifying just how spiny any given ant species is. Among Pheidole ants, we see this interesting phenomenon where certain clades have developed elaborate spines and armature relative to the rather conservative morphology of their relatives. This ‘spinescent’ morphotype has evolved independently in at least four Pheidole lineages.

Morphometric measurements from vector images from Eli Sarnat on Vimeo.

So how to measure spinescence? Ideally we’d have 3D tomography of representative specimens from each species, but that’s not very feasible. Using a stage micrometer to measure spine length relative to something like head width is another option, but it is really difficult to account for the curves and bifurcations in some of the structures.

My solution is to create a spinescence index, defined as the ratio of spine perimeter to body perimeter. In other words, what percentage out the specimen’s 2D perimeter is devoted to spines? It’s not a perfect solution, but it’s the best I’ve come up with in terms of accuracy and feasibility.

A few useful tricks for using Endnote

I’m not sure how widespread this issue is, but I find the instant formatting function of Endnote x7 to become painfully slow after my MS Word manuscripts include 100 or so references. I’d hope that there is an elegant solution to this, but I haven’t found it yet. My current strategy for maintaining sanity while composing reference-rich manuscripts is to leave the field codes unformatted and disable instant formatting. After a bit of reverse engineering I now use the following field codes to achieve the desired reference formatting. I then periodically format the references to make sure everything looks as expected. Hope this helps anyone stuck in similar predicaments.

In these examples, the author = Forel, and the year = 1909.

{Forel, 1909 #10514} = (Forel, 1909)
{Forel, 1909 #10514@@author-year} = Forel (1909)
{Forel, 1909 #10514@@hidden} = only show in bibliography
{Forel, #10514} = show only author
{, 1999 #10514} = show only year

New ant species described from Fiji – Proceratium vinaka

Francisco Hita Garcia, known more familiarly as Paco, took the lead on describing a newly discovered species of Proceratium from Fiji [1]. Vinaka is the Fijian word for thank you. My friend Moala Tokota’a told me it is the most important word in the whole language.

Proceratium vinaka

Proceratium vinaka — a new species of ant described from Fiji

To call this blind, inconspicuous species rare is rather understated. In fact, there is only one single individual worker of this species ever collected in the whole wide world. I remember the moment I first laid eyes on it. A group of us including Rosie Gillespie, some of the crew from WCS and my wife Julia were working our way down from the misty peak of Mt. Devo (Vanua Levu) after a long day. There is a single track unsealed road we were following that winded down the mountain. The upper elevations of Mt. Devo are as pristine a forest as one will find in Fiji, but there was an old garden site on the way down that was transitioning back to jungle.

Distribution map of Fijian Proceratium species

Distribution map of Fijian Proceratium species

I was scanning the ground on hand and knee, searching for a last score before heading back to the truck, when this slow-moving stout and armored ant caught my eye. It looked out of place foraging on the surface. The line from Notorious B.I.G. shoot first ask questions last compelled me to get this special creature secured in a vial before it went to ground in the leaf litter. I stuck around for a few more minutes hoping to find more of its kin, but to no avail.

That was ten years ago. Since then this single specimen has been mounted on an insect pin together with various labels detailing the location, date and circumstances of its capture. It has been resting quietly in an insect cabinet, the sole known representative of its species, awaiting a name. Thanks to the effort of Paco and Evan, Proceratium vinaka is the 12th new ant species we’ve described from Fiji over the past decade. Only 34 more to go!

[1] Hita Garcia F, EM Sarnat, EP Economo (2015) Revision of the ant genus Proceratium Roger (Hymenoptera, Proceratiinae) in Fiji. ZooKeys 475: 97-112. doi:10.3897/zookeys.475.8761 [pdf]

Using photoshop to take morphometric measurements

Taking morphometric measurements using specimen photographs from Eli Sarnat on Vimeo.

In this tutorial I use Adobe Photoshop cs6 Extended Version and a specimen photograph of an ant head to take morphometric measurements. I set a custom measurement scale in Photoshop calibrated to the scale bar embedded in the photograph, then record the measurement taken by using the Ruler Tool. Remember, the measurement will only be as accurate as the scale bar embedded in the photograph. So if the scale bar was not calibrated correctly at the time the photograph was taken, any derivative measurements will also be inaccurate.

Scratchpads tutorial: dealing with nomenclatural changes (new combinations)

Scratchpads tutorial: dealing with nomenclatural changes (new combinations) from Eli Sarnat on Vimeo.

In this tutorial I show one way for updating terms in the biological classification to reflect nomenclatural changes. The situation I deal with here is for a species included in the site which has recently been transferred to a different genus. This nomenclatural act is known in taxonomic jargon as a ‘new combination’.

In this case, the species Monomorium destructor has been transferred to the genus Trichomyrmex. I change the Unit 1 name (genus) of the term Monomorium destructor to Trichomyrmex. Then I add a new taxon term ‘Monomorium destructor‘ as a child to Trichomyrmex destructor and classify it an invalid name associated with Monomorium destructor. This way all the content previously associated with Monomorium destructor will now be associated with Trichomyrmex destructor, and anytime someone searches for the now invalid name Monomorium destructor the user will be directed to the valid combination Trichomyrmex destructor.

Pheidole flavens-complex introduced to the southwestern Pacific

Here’s the story behind the new Bioinvasions Records article on that just came out. Christian Rabeling and Ed Wilson went to Vanuatu a few years back in 2011 because it was one of the few Melanesian islands that Wilson had never collected from. They collected all the ants they could find in a general survey and kindly sent their Pheidole to the Economo lab at OIST so that I could match them against our other Pacific Pheidole collections and Evan could include them in our phylogenetic analysis. Christian and Ev caught some great Pheidole from the island, including this beautifully spinescent endemic from the sexspinosa complex shown below (CASENT0282641).

An elegant Vanuatu endemic ant species (Pheidole epem198, CASENT0282641) from the Pheidole sexspinosa complex

But one species came out in an unexpected branch on the phylogeny. Instead of coming out with the Old World clade with all the other native Melanesian ants, this one species was reliably nested within the New World clade. It’s closest relatives on the tree were two species that had been included in Corrie Moreau’s 2008 Pheidole phylogeny and id’d as P. moerens and P. flavens–both of which are considered to be invasive.

Major worker of a species from the Pheidole flavens-complex from Espiritu Santo, Vanuatu; collection code CR111110-15, specimen code CASENT0248836. (1) Lateral view, (2) fullface view, (3) dorsal view, (4) hypostomal bridge.

Major worker of a species from the Pheidole flavens-complex from Espiritu Santo, Vanuatu; collection code CR111110-15, specimen code CASENT0248836. (1) Lateral view, (2) fullface view, (3) dorsal view, (4) hypostomal bridge.


Minor worker of a species from the Pheidole flavens-complex from Espiritu Santo, Vanuatu; collection code CR111110-15, specimen code CASENT0248835. (5) Lateral view, (6) fullface view, (7) dorsal view

We wanted to let other researchers know about the spread of this trampy species into the Pacific, so we wrote up a rapid communication article for Bioinvasions Records. The idea was to get the basic information about the new discovery out as quickly as possible, so others in the region could be on the lookout for additional incursions.

The most frustrating part of this study was trying to get a name on the species. Unfortunately, the taxonomy of P. flavens and its close relatives like P. moerens and P. exigua is a super sticky mess, rife with infra-specific names, lost holotypes, and inaccurate determinations. It seems like these taxonomic morasses plague trampy species (like P. flavens and friends) much more often than your average ant species.

Why is it that trampy species so often belong to species-complexes? What are species-complexes, anyways? I suppose I’d define them as geographically distinct populations that are somewhere on the continuum of streching from a recently coalesced species radiation on one end to a network of geographically isolated groups with some low amount of gene flow still persisting. For the taxonomist or even the molecular systematist there is no clear way to know whether to call these things five geographically isolated species or one widespread species.

Whatever the population on Vanuatu turns out to be, it doesn’t match the neotype of P. flavens or the syntypes of P. moerens, so for now we have to settle for calling it a member of the flavens-complex and hope that someone tries to untangle this taxonomic knot in the near future.

EM Sarnat, C Rabeling, EP Economo & EO Wilson (2014) First record of a species from the New World Pheidole flavens-complex (Hymenoptera: Formicidae) introduced to the southwestern Pacific. Bioinvasions Records 3: 301-307. | PDF


How to identify Solenopsis invicta using Antkey

In this tutorial I demonstrate a few different approaches to identifying Solenopsis invicta, also known as the Red Imported Fire Ant (RIFA), using Antkey. The key can be accessed at

How to identify Solenopsis invicta using Antkey from Eli Sarnat on Vimeo.

How to use Antkey’s Lucid3 interactive key

In this tutorial I demonstrate how to make the most effective use of Antkey’s interactive Lucid3 key for identifying invasive and introduced ants. There are tips on how to use features like the ‘best’ and ‘next best’ buttons, what the different panels mean, how to make effective use of thumbnail and pop-up images and how to adjust the text size.

How to use Lucid Key for identifying ants from Eli Sarnat on Vimeo.

2014 July 21-31 Borneo: Maliau Basin
Organized by the California Academy of Sciences
Application link
Pay Course fees before July 1 (Pay online)

Ant Course 2014 - Borneo


July 20 participants arrive in Kota Kinabalu
July 21 Depart Kota Kinabalu : 6-8  hour bus ride to Maliau Basin
July 31 Depart Maliau Basin to Kota Kinabalu

COURSE OBJECTIVES. – ANT COURSE is designed for systematists, ecologists, behaviorists, conservation biologists, and other biologists whose research requires a greater understanding of ant taxonomy and field techniques.  In 2014, emphasis is on the identification of the ant genera and species occurring in the Asian tropics.  Lectures will include background information on the ecology, life histories and evolution of ants.  Field trips emphasize collecting and sampling techniques, and associated lab work focuses specimen preparation, sorting and labeling.  Information on equipment, literature, and myrmecological contacts are also presented.

COURSE SIGNIFICANCE. – Ant Course is a unique opportunity to acquire training that is unavailable elsewhere.  This course will provide students with 1) the confidence and skills to identify Southeast Asian tropical ant genera; 2) an understanding of modern specimen processing and curation techniques; 3) an appreciation for the biological diversity of ants; and 4) experience keying to the species level.

SPONSORED BY. – California Academy of Sciences and The Arthur Lawrence Green Memorial Fund, Museum of Comparative Zoology, Harvard University

LOCATION. – ANT COURSE will be based at the Maliau Basin Studies Centre in in Sabah, Malaysia.  The Centre is part of the Maliau Basin Conservation Area that includes 12 forest types, comprising mainly lower montane forest dominated by Agathis trees, montane heath forest and lowland, and hill diperocarp forest.

PARTICIPANT ACCEPTANCE CRITERIA. – ANT COURSE is open to all interested individuals, including students, professors and motivated amateurs (citizen scientists). Priority will be given to those students for whom the course will have a significant impact on their research with ants. We aim to include students with a diverse interest in biology, including ant systematics, ecology, behavioral biology, genetics, and conservation.  An entomological background is not required.  The high instructor to student ratio will allow students to receive individual attention. ANT COURSE is presented in English and limited to 30 participants

COSTS. – Course fees for the 10-day COURSE are $975 for current students (undergraduate and graduate) and $1275 for non-students (postdocs and professionals).  Transportation costs between home and Koto Kinabalu, and hotel fees in Kota Kinabalu are to be borne by all participants. Pay course fees by July 1 at:

FELLOWSHIPS. – Those interested in attending the course should seek all possible avenues to secure funding on their own for the course.  Each year we strive to raise funds to support a few students by offering discounted tuition fees. You should only apply for the Ant Course fellowship if you cannot find other support and it is essential for your participation in the course. Please notify the course if your funding request status changes before the application due date.

COURSE APPLICATION. – Application and course information at  The first step is to fill out a form at:

Note this form requires a short statement of your research interests and future plans and a statement of your reasons for wishing to participate in the course. Also requires is one letter of reference from a professor or colleague familiar with your work to be submitted by the referee at:

You will be notified of your acceptance to the Course around APRIL 15-20.

ANT COURSE is limited to 30 participants.  Selection of participants will be carried out by committee, based on your reasons for wishing to take the course at this time.  Priority will be given to those students for whom the course will have a significant impact on their research with ants.  Because the Course is offered yearly, and because many well-qualified candidates are not accepted because of limited capacity, we urge applicants not selected for this session to apply again the following year.


Brian Fisher (Coordinator), Leeanne Alsonso, Himender Bharti, Katsuyuki Eguchi , Flavia Esteves, Brian Fisher, Benoit Guénard , Roberto Keller, Laurent Keller, Jack Longino, Corrie Moreau, Chrstian Peeters, Simon Robson, Eli Sarnat, Steve Shattuck, Andy Suarez, Phil Ward

Malaysian Collaborators

Dr. Charles Varaippan, Director & Dr. Bakhtiar Yahya, Institute for Tropical Biology & Conservation, University of Malaysia, Sabah; Dr. Arthur Y. C. Chung, Forest Research Centre, Sabah Forestry Department

New line drawings for undescribed Fijian Pristomyrmex

Here are a few line drawings I am working on for the description of an undescribed species of Fijian Pristomyrmex. In the Ants of Fiji monograph, this species is listed as Pristomyrmex sp. FJ02.

Full face view of Pristomyrmex sp. FJ02. Line drawings can allow for better representation of important taxonomic features compared to specimen photographs. For example, the mandibular tooth structure is essential for Pristomyrmex species identification. The mandibular teeth on the specimen photograph used as a template for this illustration were obscured and difficult to see. The line drawing shows them quite clearly.

Rendering the characteristic foveae (circular depressions) of Pristomyrmex was a bit challenging, and I am sure my method could use some improvement. I began by using the Ellipse Tool to get the basic shapes, and then rotated them according to the template specimen. Next I used the eraser tool to break the foveae that appeared somewhat shallow. I then selected all the ‘broken’ foveae and applied a stroke profile that tapers strongly on both ends. For the ‘unbroken’ foveae I selected each individually and used the Width Tool to constrict the ellipses at a single point.

Profile of Pristomyrmex sp. FJ02. Of the over 50 known species of Pristomyrmex, this is only the second that lacks propodeal spines. The other, P. inermis, occurs in New Guinea.

I also used a new technique for the hairs on this illustration. I decided to use the Outline Stroke function for all of the hairs, and selected a white outline stroke. This allows for a white break where hairs overlap the ant profile and other strokes.