Formicinae, Formicidae, Hymenoptera, Insecta, Arthropoda, Animalia
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Range
Costa Rica (rainforest sites throughout Costa Rica; La Selva and adjacent slopes to 700m; common in Penas Blancas Valley east of Monteverde, to 900m, but not in Monteverde cloudforest or community area; occurs in Corcovado, and also at Wilson Botanical Garden at 1200m elevation).
Identification
Minor worker: head subquadrate; scapes with no erect setae; lateral margins of head with no or few projecting setae (see below); dorsal and lateral faces of pronotum sharply differentiated, meeting at a slightly projecting keel anterolaterally, keel fading posteriorly; dorsal and lateral faces of propodeum meeting at distinct angle; dorsal and posterior faces of propodeum distinct, meeting at an angle, subequal in length; dorsal profile of pronotum, mesonotum, and dorsal face of propodeum forming even convexity; anterior and posterior faces of petiole converge to sharp transverse crest at apex; first gastral tergite with moderately abundant to dense appressed pubescence (see below), moderately abundant erect setae; face and mesosoma densely micropunctate, sublucid with bronze reflections; gaster shagreened, mat; integument generally black, legs and scapes orange, posterior borders of gastral tegites yellow, forming sharply defined bands.
This species appears to have two distinct forms with a parapatric distribution (narrow zones of sympatry and largely non-overlapping ranges). The collections from La Selva, the adjacent slope to 600m, and Penas Blancas have dense yellow pubescence on the gaster, and there are 2-3 short erect setae on the cheeks near the mandibular insertions. The scapes seem a bit longer, but measurements needed to confirm this. Collections from Estacion Carrillo at 500m in Braulio Carrillo National Park, Penas Blancas, Wilson Botanical Garden, and Corcovado have less dense, silvery pubescence on the gaster, and 0-1 erect setae on the cheeks. Thus the forms are sympatric in Penas Blancas and 500-600m elevation in Braulio Carrillo.
Major worker: face subquadrate; face yellow up to below eyes; face and cheeks with abundant short, stiff to somewhat clavate, erect setae.
The gastral pilosity characters for the different forms discussed above are similarly distinct in the majors.
Similar species: cuneidorsus, JTL-015, JTL-028.
Natural History
This species is moderately common in lowland rainforest sites in Costa Rica. It generally occurs in primary forest, where diurnal foragers are found on vegetation and in recent treefalls. I have observed five nests, and they have all been in chambers in epiphyte mats, either entirely embedded in the mat, or at the interface of mat and tree bark. The nests are small, on the order of a few dozen workers or less, but I do not know if colonies are polydomous.
It is interesting to contrast this epiphyte-nesting species with linnaei, which nests in dead branches. At La Selva the two species seem similar in abundance when hand collected (searching in treefalls), yet linnaei is relatively common in canopy fogging samples, and JTL-027 is rare. This reinforces the observation that canopy fogging undersamples arthropods that live in epiphyte mats.
Notes
This is basically a lowland version of cuneidorsus, differing mainly in degree of pilosity on face.
Page author:
John T. Longino, The Evergreen State College, Olympia WA 98505 USA.longinoj@evergreen.edu
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