Formicinae, Formicidae, Hymenoptera, Insecta, Arthropoda, Animalia
Costa Rica (type locality), Mexico. Costa Rica: Pacific slope below Monteverde, at 800m.
Face smooth (or densely punctate; see note below), with abundant erect setae; scapes surpass vertex margin by about length of first funicular segment; metanotum deeply impressed, mesosoma hour-glass shaped; pronotum shiny, katepisternum and side of propodeum shagreened; mesosomal dorsum, including dorsal face of propodeum, with abundant erect setae; first gastral tergite with abundant erect setae, no appressed pubescence; scapes and legs with abundant long erect pubescence.
This very distinctive species has only been collected three times, from two sites on the Pacific slope just below Monteverde. Both sites were about 800m elevation and were in the moist forest transition zone between cloud forest and lowland dry forest climate zones. Both areas were mosaics of forest patches, pastures, scrubby vegetation, and road edges. All three collections were of workers on vegetation in open scrubby vegetation. In the field, these ants look and behave remarkably like Crematogaster.
This peculiar species has characters of both Brachymyrmex and Myrmelachista. The size and shape of the mesosoma is very like Myrmelachista zeledoni, a common species in the same areas where nebulosus occurs, and the visual similarity to Crematogaster is shared with several montane Myrmelachista species. Yet the antennae are 9-segmented and there is no antennal club.
Note, 9 June 2008: One of us (JTL) just collected a worker of this species from the Sierra Madre de Chiapas in Chiapas, Mexico, as part of the LLAMA project. The isolated worker was in the "stray ants" vial, collected over a 5-day period near the community of Sierra Morena.
The worker differs from Costa Rican material in having the face completely and strongly punctate. Given the large distance between Chiapas and Costa Rica and the liklihood of undiscovered populations in between, there is little value in considering it a separate species at this time.
LaPolla, J. S., and J. T. Longino. 2006. An unusual new Brachymyrmex Mayr (Hymenoptera: Formicidae) from Costa Rica, with implications for the phylogeny of the Lasiine tribe group. Proceedings of the Entomological Society of Washington 108:297-305.
John LaPolla, Department of Entomology, USNM, Washington, DC, USA. firstname.lastname@example.org
John T. Longino, The Evergreen State College, Olympia WA 98505 USA.email@example.com
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