Taxonomic History (provided by Barry Bolton, 2019)
Distribution: Geographic regions
(According to curated Geolocale/Taxon lists): Americas: Costa Rica
, Mexico Biogeographic regions
(According to curated Bioregion/Taxon lists): Neotropical
Southern Mexico to Costa Rica.
In Costa Rica, 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
. Collections from Honduras and Chiapas, Mexico, have also been from cloud forest sites. They have been collected in pan traps, a beating sample, and a hand-collected forager.
Face smooth and shiny or densely punctate, 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 peculiar species has characters of both Brachymyrmex
. 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.
Costa Rican specimens and a collection from Celaque National Park in Honduras have the face smooth and shiny. Collections from Monte Galan, Honduras, and Sierra Morena in the Sierra Madre de Chiapas have the face uniformly and densely punctate. Thus these characters are curiously interdigitated geographically.
Specimen Habitat Summary
Found most commonly in these habitats: 1 times found in moist forest and second growth veg., 2 times found in Roadside vegetation, 1 times found in pine-oak forest, 1 times found in 2nd growth veg..
Found most commonly in these microhabitats: 3 times yellow pan trap, 1 times columns on low veg., 1 times Workers on foliage of Cordia alliodora, 1 times beating vegetation, 1 times workers on tree trunk, 1 times sweeping, 1 times ex sifted leaf litter, 1 times blue pan trap.
Collected most commonly using these methods: 3 times search, 3 times yellow pan trap, 1 times Beating, 1 times blue pan trap, 1 times Maxi Winkler, 1 times sweeping.
Elevations: collected from 800 - 1408 meters, 1107 meters average
Type specimens: Holotype Brachymyrmex nebulosus: lacment143546; Paratype Brachymyrmex nebulosus: inbiocri001279916, inbiocri002281199
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