Dolichoderinae, Formicidae, Hymenoptera, Insecta, Arthropoda, Animalia
Queen, face view (original line drawing, reduced line drawing); mandible (small, large, original line drawing, reduced line drawing); petiole, lateral view (small, large, original line drawing, reduced line drawing).
Worker, mesosoma, lateral view (original line drawing, reduced line drawing).
Mexico to Costa Rica. Costa Rica: widespread; more common in northwestern lowlands.
Measurements (n=9): HLA 1.90 (1.83-1.93), HW 1.30 (1.27-1.36), SL 0.84 (0.83-0.86, n=8), CI 70 (69-73), SI 45 (44-46, n=8).
Palpal formula 5,3; middle and hind tibia with prominent pectinate apical spur; dorsal surface of mandible largely smooth, with sparse piligerous puncta, setae in puncta short, little longer than width of puncta, larger puncta with long setae near masticatory margin; medial and lateral clypeal lobes at about same level; head rectangular, posterior margin distinctly excised medially; petiolar node short, bluntly rounded; posteroventral petiolar lobe shallow, evenly convex from front to back; scape with sparse erect setae, inconspicuous and only visible at certain angles, about as long as one quarter maximum width of scape; middle and hind tibia with sparse erect setae, fine, inconspicuous, longest about as long as one fifth maximum width of tibia (MTSC 5-10), side of head with 0-2 short erect setae near mandibular insertion, lacking setae elsewhere, posterior margin of head with sparse short setae; pronotum with posterior row of erect setae, mesoscutum, scutellum and propodeum with sparse erect setae, petiolar node with rim of erect pubescence, in profile with 0-4 erect setae projecting above apex, posteroventral lobe with layer of dense, whitish, erect, pubescence; gastral terga with sparse erect setae; general body color yellow orange, gastral terga with prominent medial dark brown bands, mandibles red brown, middle and hind femur and tibia variably infuscated.
Measurements (n=9): HLA 1.62 (1.37-1.78), HW 1.28 (1.11-1.42), SL 0.77 (0.75-0.81), CI 81 (76-83), SI 48 (45-56).
Palpal formula 5,3; middle and hind tibia with prominent pectinate apical spur; dorsal surface of mandible smooth and shining, with moderately abundant piligerous puncta; medial and lateral clypeal lobes at about same level; head elongate with weakly convex sides, strongly excavate posterior margin; in lateral profile pronotum shallowly convex, mesonotum more strongly convex and forming separate convexity that protrudes above pronotum; scape with sparse, inconspicuous erect setae, length of setae about one quarter maximum width of scape; mid and hind tibia with moderately abundant erect setae, setae inconspicuous, longest about one quarter maximum width of tibia; side of head with 1-2 short erect setae near mandibular insertion, absent elsewhere along side; posterior margin of head with sparse short erect setae; pronotum, mesonotum, and dorsal face of propodeum with sparse, short, erect setae; color of smaller workers brown, approaching coloration of queen on larger workers.
The yellow color and large size distinguishes queens of A. beltii from all other species with elongate rectangular heads. The workers of A. beltii are most similar to workers of A. oecocordia. The largest workers of the former have yellow faces, while workers of the latter always have brown faces.
The taxonomy and biology of A. beltii is reviewed in Longino (1996).
Azteca beltii is most abundant in moist and dry forest habitats, although it occurs as a low density element in wet forests. At La Selva Biological station in the Atlantic lowlands of Costa Rica, workers have been collected in a Ficus tree in the lab clearing and from one tree (of about 50) sampled by canopy fogging. It is likely that in wet forests it is found in highly insolated environments like the uppermost portion of the canopy and perhaps relict trees in clearings. In dry forest habitats it is known to nest in live stems in a wide variety of plant species. Very often it nests in myrmecophytes such as Cecropia, Cordia alliodora, and Triplaris melaenodendron, but it has also been found nesting in non-myrmecophytes Piper tuberculatum (Piperaceae), Cochlospermum vitifolium (Cochlospermaceae), and Pithecellobium saman (Fabaceae). Colonies are large and polydomous, nesting in the live shoot tips over large portions of the crowns of trees. But the workers are timid and appear to spend most of their time inside the stems, so they are not conspicuous ants on the surface. The nest chambers in the live stems usually have very high densities of coccoid Hemiptera. A tree with a large colony of A. beltii can appear herbivore-free on the surface, yet harbor a very large population of Hemiptera that is hidden from view inside of the stems.
I observed a founding queen in a cut branch of a Triplaris tree. The terminal 20-40cm of the branch, the leafy part, was unoccupied. Lower in the branch, a founding queen of A. longiceps and one of A. beltii occupied adjacent cavities. The cavities of the two queens were formerly continuous through a perforated septum, but a plug of particulate matter separated the two. The plug was asymmetrical, as though built from the beltii side. This observation, together with the catholic nesting habits and somewhat bristly mandibles of beltii, led me to speculate that beltii might be a secondary occupant of ant-plants (Longino 1996). Azteca beltii may rely on primary occupants to excavate entrances, entering subsequently and either fighting or walling off the primary occupant.
The species as currently delimited occurs from Mexico to Panama, but very similar or possibly conspecific forms occur throughout South America. Azteca fasciata and A. mayrii are two South American taxa that are closely related to or conspecific with A. beltii.
John T. Longino, The Evergreen State College, Olympia WA 98505 USA. firstname.lastname@example.org
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