Formicidae, Hymenoptera, Insecta, Arthropoda, Animalia
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Identification
Minor worker: head length 0.72mm, head width 0.67mm, scape length 0.71mm, Webers length 0.94mm (n=1). Scapes feebly foveolate; head broadly rounded behind; promesonotum evenly arched, mesonotal suture absent; propodeal spines short, upturned; face, pronotum, and gaster smooth and shining; katepisternum and propodeum coarsely rugose and shining; dorsal pilosity abundant, long, flexuous, those on posterior half of promesonotum curved anteriorly; color red brown.
Major worker: head length 2.19mm, head width 1.79mm, scape length 0.77mm (n=1). Face densely reticulate rugose; conspicuous antennal scrobes extending to just above eye, surface of scrobe smooth and shiny; hypostomal margin with low, broadly rounded medial lobe, pair of robust subtriangular teeth located closer to midline than to recessed teeth flanking mandibles; dorsal pilosity abundant; head with abundant setae projecting from sides of head in face view.
Range
Costa Rica: Atlantic lowlands (La Selva Biological Station and adjacent Barva transect to 500m elevation).
Natural History
This species inhabits lowland rainforest and so far is only known from a small area in Costa Rica. Workers are rare in Winkler samples, Berlese samples, and at baits on forest floor. Workers occasionally occur in Malaise samples.
Nests are in clay soil. Stefan Cover and E. O. Wilson independently observed nests in clay soil at La Selva. Longino observed a nest in a clay bank at the Cantarrana site on the Barva transect (300m elevation). A column of workers was climbing up the bank and entering a hole. Several centimeters deep was a chamber about 3cm wide and 5mm tall, filled with workers and brood. A small tunnel led down from this chamber to a very similar lower one, 1-2cm below the first. When the top chamber was opened, workers flowed down into the lower chamber. When the lower chamber was opened, workers continued to flow down another tunnel, presumably to a yet lower chamber that was not excavated. There was abundant brood, many large soldiers, and the occasional adult male.
Comments
This species has a complicated past with respect to the Longino specimen database and identification history. There is a second species, undescribed, with similar minor workers. In the early 1990's it was recognized as distinct and given the morphospecies code JTL-081. At this point vestita was known from majors and minors, JTL-081 only from minors. Later we decided that vestita was more variable than thought and we started identifying all material as vestita (treating the morphospecies JTL-081 as a synonym of vestita). In 2008 Longino excavated two nests in Pe–as Blancas, obtaining good nest series with majors. The majors were related to but definitely distinct from vestita, and the minors were the old morphospecies JTL-081. The difference has also been supported by DNA barcoding data provided by Alex Smith at BOLD. A new morphospecies code, JTL-156, has been assigned to this undescribed species. A review of specimens in the Longino collection at Evergreen revealed that JTL-156 was actually far more abundant than vestita in the abundant material from the ALAS project and the TEAM project at La Selva, mostly obtained in Winkler and Berlese samples, and baits. There are about 80 specimens at INBio and in the database that are identified as vestita. The majority of these are probably JTL-156.
Minors of JTL-156 differ from vestita in the sculpture of the katepisternum, propodeum, and mandible. In vestita the katepisternum and propodeum (dorsal and lateral surfaces) are overlain with coarse rugae, and the dorsal surface of the mandible is completely smooth and shining. In JTL-156 katepisternum and propodeum are mostly smooth and shining, and the mandible has a variable extent of roughened sculpture on the base of the dorsal surface.
Page authors:
John T. Longino, The Evergreen State College, Olympia WA 98505 USA. longinoj@evergreen.edu
Stefan Cover, Museum of Comparative Zoology, Harvard University, Cambridge MA 02138 USA. scover@oeb.harvard.edu
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